#Nipah virus #infection - #Bangladesh (#WHO D.O.N., Feb. 7 '26)

 

6 February 2026

Situation at a glance

On 3 February 2026, the International Health Regulations National Focal Point (IHR NFP) for Bangladesh notified WHO of one confirmed case of Nipah virus (NiV) infection in Rajshahi Division. 

The patient developed fever and neurological symptoms on 21 January. 

Nipah virus infection was laboratory-confirmed on 29 January. 

The patient reported no travel history but had a history of consuming raw date palm sap. 

All 35 contact-persons are being monitored and have tested negative for NiV and no further cases have been detected to date. 

Bangladesh regularly has small NiV outbreaks, with cases reported at different times of the year, though outbreaks tend to occur between December and April corresponding with the harvesting and consumption of date palm sap. 

The Ministry of Health and Family Welfare in Bangladesh has implemented several public health measures. 

WHO assesses the overall public health risk posed by NiV to be low at the national, the regional and global level. 

The risk of international disease spread is considered low.

Description of the situation

On 3 February 2026, the Bangladesh IHR NFP notified WHO of one confirmed case of NiV infection that occurred in Rajshahi Division, northwestern Bangladesh. 

The case was confirmed by Polymerase Chain Reaction (PCR) and Enzyme-Linked Immunosorbent Assay (ELISA) testing on 29 January 2026.

The patient is female, aged between 40-50 years, residing in Naogaon District, Rajshahi Division. 

She developed symptoms consistent with NiV infection on 21 January, including fever, headache, muscle cramps, loss of appetite (anorexia), weakness, and vomiting, followed by hypersalivation, disorientation, and convulsion. 

On 27 January, she became unconscious and was referred by a local physician to a tertiary hospital. 

She was admitted on 28 January, and the Nipah surveillance team collected throat swabs and blood samples. The patient died the same day.

The patient reported repeated consumption of raw date palm sap between 5 and 20 January 2026. 

Following the confirmed diagnosis, an outbreak investigation team, including One Health stakeholders, started investigations on 30 January.

A total of 35 contact persons has been identified, including three household contact persons, 14 community contact persons and 18 hospital contact persons. 

Samples were collected from six symptomatic contact persons, including three from household, two from communities and one from hospital. 

All six samples tested negative for NiV infection by PCR and anti-Nipah IgM antibody detection by ELISA. 

As of 3 February, no additional cases have been identified. Contact persons are under monitoring.

Bangladesh reported its first case of NiV infection in 2001. Since then, human infections have been reported almost every year. In 2025, four laboratory-confirmed fatal cases were reported from Bangladesh.

Epidemiology

NiV infection is a zoonotic disease transmitted to humans through infected animals (such as bats), or food contaminated with saliva, urine, and excreta of infected animals. It can also be transmitted directly from person to person through close contact with an infected person. Fruit bats, also known as flying foxes, (Pteropus species) are the natural hosts for the virus. 

The incubation period ranges from 3 to 14 days. In some rare cases, incubation of up to 45 days has been reported. Laboratory diagnosis of a patient with a clinical history of NiV infection can be made during the acute and convalescent phases of the disease by using a combination of tests. The main tests used are RT-PCR from bodily fluids and antibody detection via ELISA. 

Human infections range from asymptomatic infection to acute respiratory infection (mild, severe), and fatal encephalitis (brain swelling). 

Infected people initially develop symptoms including fever, headaches, myalgia (muscle pain), vomiting and sore throat. This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis. Some people can experience atypical pneumonia and severe respiratory problems, including acute respiratory distress. Encephalitis and seizures occur in severe cases, progressing to coma within 24 to 48 hours. 

Further information about NiV infection can be found here. 

The CFR in previous outbreaks across Bangladesh, India, Malaysia, Philippines and Singapore ranged from 40% to 75%, depending on local capabilities for early detection and clinical management. There are currently no licensed medicines or vaccines specific for NiV infection. Early intensive supportive care is recommended to treat severe respiratory and neurologic complications. Henipavirus nipahense (or Nipah virus) is considered a priority pathogen for the acceleration of medical countermeasures to respond to epidemics and pandemics as part of the WHO R&D Blueprint for Epidemics.

Public health response

Several public health measures have been implemented by local authorities, including:

-- On 30 January 2026, the Ministry of Health and Family Welfare (MoHFW), in collaboration with relevant sectors, initiated an outbreak investigation using a coordinated One Health approach.

-- Active contact tracing was implemented to identify and monitor exposed individuals.

-- Preparations were undertaken to conduct an advocacy meeting involving Civil Surgeons, Upazila Health Officers, Hospital Directors, and Superintendents from Nipah-endemic districts.

-- Community awareness programmes are being planned with the involvement of field-level health workers.

-- Audio-visual health education materials on NiV infection are being developed for point-of-entry staff and travellers.

The support provided by WHO includes: 

-- WHO is monitoring the situation closely, in coordination with the national and sub-national health authorities.

-- WHO facilitated IHR event communication to notify the case.  

WHO risk assessment

Nipah virus is a zoonotic pathogen with a high death rate and no licensed vaccine or treatment, though early supportive treatment can save lives. Its reservoirs are fruit bats or flying foxes (bats of the Pteropus genus), which are distributed in the coastal regions and on several islands in the Indian ocean, India, south-east Asia and Oceania. The virus can be transmitted to humans from wild and domestic animals. Secondary human-to-human transmissions are also possible. Cases of Nipah virus infection were first reported in 1998 and since then have been reported in Bangladesh, India, Malaysia, Philippines and Singapore. The virus is present in Bangladesh, while NiV cases are reported throughout the year, outbreaks tend to occur between December and April corresponding with the harvesting and consumption of date palm sap. Clusters of cases are mainly reported in the country’s central and northwest districts. 

To date, since 2001 Bangladesh has documented 348 NiV disease cases, including 250 deaths, corresponding to an overall case fatality rate of 72%. Nearly half of these cases (n=162) were primary cases with a confirmed history of consuming raw date palm sap or tari (fermented date palm sap), while 29% resulted from direct person-to-person transmission. Most cases detected in Bangladesh were reported through December to April, suggesting a seasonal pattern.  

Based on the current available information, WHO assesses the overall public health risk posed by NiV at the national level to be low due to the following reasons:

-- The case fatality rate from NiV infection is high. There are currently no specific drugs or vaccines available for NiV infection, although WHO has identified Nipah as a priority disease for research under WHO Research and Development Blueprint. Intensive supportive care is recommended for the treatment of severe respiratory and neurologic complications. 

-- The initial signs and symptoms of NiV infection are non-specific, and the diagnosis is often not suspected at the time of presentation. This can delay timely diagnosis and create challenges in outbreak detection, effective and timely infection control measures, and outbreak response activities. 

-- Fruit bats (Pteropus spp.), as a natural reservoir of the Nipah virus, are present in Bangladesh and repeated spillover of the virus from its reservoir to the human population has been demonstrated. 

-- Despite ongoing efforts at risk communication and community engagement to address awareness, there is continued consumption of raw date palm sap by the community. 

-- However, the yearly number of NiV cases reported in Bangladesh remains under 10 since 2016, with exception in 2023 when 14 cases were reported. Although human-to-human transmission has been reported in previous outbreaks, it has been less frequent in recent years. 

-- In addition, strong public health measures are in place to detect and control outbreaks, including a hospital-based systematic human NiV infection surveillance system which has been established since 2006, the utilization of the National Rapid Response Team (NRRT) at the central level and the Rapid Response Team (RRT) at the district level and the capacity to rapidly test samples. 

-- Bangladesh borders India and Myanmar, and WHO assesses the risk at the regional level to be low. While there have not been any instances of cross-border transmission by humans previously, the risk remains, given shared ecological corridor for the virus's natural host Pteropus bats and occurrence among domestic animals and humans previously in both countries. However, India has strong capacities and experience of controlling previous NiV outbreaks. 

WHO assesses the risk at the global level to be low, as there have been no previous confirmed cases outside Bangladesh, India, Malaysia, Philippines and Singapore. 

WHO advice

In the absence of a licensed vaccine or specific therapeutic treatment for Nipah virus disease, reducing or preventing infection in people relies on raising awareness of the risk factors. This includes providing guidance on and reinforcing risk communication messages about the measures that people can take to reduce exposure to the Nipah virus. Case management should focus on delivering timely supportive care, supported by an effective laboratory system and adequate infection prevention and control measures in health facilities. Intensive supportive care is recommended for treatment of severe respiratory and neurologic complications.  

Public health educational messages should focus on: 

-- Reducing the risk of bat-to-human transmission 

-- Efforts to prevent transmission should first focus on decreasing bat access to date palm sap and other fresh food products. Freshly collected date palm juice should be boiled, and fruits should be thoroughly washed and peeled before consumption. Fruits with signs of bat bites should be discarded. Areas where bats are known to roost should be avoided.

Reducing the risk of human-to-human transmission:

-- Close unprotected physical contact with NiV-infected people should be avoided. Regular hand washing should be carried out after caring for or visiting sick people along other preventive measures. 

-- People experiencing Nipah-like symptoms should be referred to a health facility, as early supportive care is key in the absence of treatment. Contact tracing and monitoring are also key to mitigate human-to-human transmission.  

Controlling infection in health care settings:

-- Health and care workers caring for patients with suspected or confirmed infection, or handling specimens from them, should always implement standard precautions for infection prevention and control at all times, for all patients. 

-- When caring for patients with suspected or confirmed NiV, WHO advises the use of contact and droplet precautions including a well-fitting medical mask, eye protection, a fluid-resistant gown, and examination gloves. Airborne precautions should be implemented during aerosol-generating procedures, including placing the patient in an airborne-infection isolation room and the use of a fit-tested filtering facepiece respirator instead of a medical mask. Suspected or confirmed cases of NiV should be placed in a single-patient room.  For family members and caregivers visiting patients with suspected or confirmed Nipah virus, similar precautions should be applied.     

-- Samples taken from people and animals with suspected NiV infection should be handled by trained staff working in suitably equipped laboratories. 

Based on the currently available information, WHO does not recommend any travel and/or trade restrictions.

Further information

1) World Health Organization. WHO South-East Asia Regional Strategy for the prevention and control of Nipah virus infection 2023–2030. Available at: https://www.who.int/publications/i/item/9789290210849 

2) World Health Organization. Technical Brief: Enhancing readiness for a Nipah virus event in countries not reporting a Nipah virus event. Interim Document, February 2024. Available at: https://www.who.int/publications/i/item/9789290211273  

3) World Health Organization. Nipah virus. Available at: https://www.who.int/news-room/fact-sheets/detail/nipah-virus     

4) World Health Organization. Nipah virus infection. Available at: https://www.who.int/health-topics/nipah-virus-infection#tab=tab_1   

5) World Health Organization (27 February 2024). Disease Outbreak News; Nipah virus infection – Bangladesh. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON508  

6) World Health Organization (18 September 2025). Disease Outbreak News; Nipah virus infection – Bangladesh. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON582  

7) Nipah Situation Dashboard, Institute of Epidemiology, Disease Control and Research (IEDCR) https://www.iedcr.gov.bd/site/page/d5c87d45-b8cf-4a96-9f94-7170e017c9ce/- 

8) Nipah Virus Transmission in Bangladesh https://www.iedcr.gov.bd/site/page/03d6e960-2539-4966-8788-4a12753e410d/-    

10) Nipah virus outbreak with person-to-person transmission in a district of Bangladesh, 2007 https://pubmed.ncbi.nlm.nih.gov/20380769/  

11) Foodborne Transmission of Nipah Virus, Bangladesh https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291367    

12) Nipah virus outbreak trends in Bangladesh during the period 2001 to 2024: a brief review https://pmc.ncbi.nlm.nih.gov/articles/PMC11872451/  

13) Nipah Virus Disease: Epidemiological, Clinical, Diagnostic and Legislative Aspects of This Unpredictable Emerging Zoonosis https://www.mdpi.com/2076-2615/13/1/159 - B66-animals-13-00159     

14) The Ecology of Nipah Virus in Bangladesh: A Nexus of Land-Use Change and Opportunistic Feeding Behavior in Bats https://pmc.ncbi.nlm.nih.gov/articles/PMC7910977/ 

15) World Health Organization (30 January 2026). Disease Outbreak News; Nipah virus infection – India. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON593

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON594

____

#Cambodia notified two additional #human cases of infection with #influenza #H5N1, #Bangladesh one case of #H5, #China four cases of #H9N2 (HK CHP, Nov. 21 '25)

{Excerpt}

This Week:

[Date of report - Country - Province / Region District / City - Sex - Age - Condition at time of reporting  - Subtype of virus]

1) .../10/2025 - Cambodia - Takeo Province - F - 14 - Hospitalised - H5N1 

2) 16/10/2025 - Cambodia - Kampong Speu Province - F - 3 - Under intensive care - H5N1

(...)

[Place of occurrence - No. of cases  (No. of deaths) - Details]

-- Bangladesh - 1(0) 

- Avian influenza A(H5): 

1) Sylhet Division: A boy with onset on July 27, 2025. 

-- Chinese Mainland - 4(0) 

- Avian influenza A(H9N2): 

- Guangdong Province: 

1) An individual with onset in February 2025. The case was retrospectively reported. 

- Guangxi Zhuang Autonomous Region: 

2, 3) Two individuals with onset in February 2025. Both cases were retrospectively reported.  

- Tianjin Municipality: 

4) An individual with onset in February 2025. The case was retrospectively reported. 

-- Mexico - 1(0) 

- Avian influenza A(H5): 

1) Mexico City: A 23-year-old woman with onset on September 14, 2025. 

(...)

Source: Centre for Health Protection, Hong Kong PRC SAR, https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk42.pdf

____

#Influenza at the #human - #animal #interface - Summary and #risk #assessment, from 26 August to 29 September 2025 (#WHO, edited)

 

New human cases {1,2}: 

-- From 26 August to 29 September 2025, based on reporting date, the detection of influenza A(H5) in one human, influenza A(H5N1) in one human, influenza A(H9N2) in eight humans and an influenza A(H1N1) variant ((H1N1)v) virus in one human were reported officially.  

Circulation of influenza viruses with zoonotic potential in animals: 

-- High pathogenicity avian influenza (HPAI) events in poultry and non-poultry animal species continue to be reported to the World Organisation for Animal Health (WOAH).{3} 

-- The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4} 

Risk assessment {5}: 

-- Sustained human to human transmission has not been reported from these events. 

-- Based on information available at the time of this risk assessment update, the overall public health risk from currently known influenza A viruses detected at the human-animal interface has not changed and remains low. 

-- The occurrence of sustained human-to-human transmission of these viruses is currently considered unlikely. 

-- Although human infections with viruses of animal origin are infrequent, they are not unexpected at the human-animal interface.  

Risk management: 

-- Candidate vaccine viruses (CVVs) for zoonotic influenza viruses for pandemic preparedness purposes were reviewed and updated at the September 2025 WHO consultation on influenza vaccine composition for use in the southern hemisphere 2026 influenza season. 

-- A detailed summary of zoonotic influenza viruses characterized since February 2025 is published here and updated CVVs lists are published here. 

IHR compliance: 

-- All human infections caused by a new influenza subtype are required to be reported under the International Health Regulations (IHR).{6} 

-- This includes any influenza A virus that has demonstrated the capacity to infect a human and its haemagglutinin (HA) gene (or protein) is not a mutated form of those, i.e. A(H1) or A(H3), circulating widely in the human population. 

-- Information from these notifications is critical to inform risk assessments for influenza at the human-animal interface.

Avian influenza viruses in humans 

Current situation:  

-- Since the last risk assessment of 25 August 2025, one laboratory-confirmed human case of A(H5) infection was detected in Bangladesh, and one laboratory-confirmed human case of A(H5N1) virus infection was detected in Cambodia. 

A(H5), Bangladesh 

-- On 19 August 2025, Bangladesh notified WHO of one laboratory-confirmed human infection with avian influenza A(H5) virus in a boy in Sylhet Division. 

-- The case developed fever and cough on 27 July and was admitted to hospital on 1 August. 

-- Oropharyngeal and nasopharyngeal swabs collected on 4 August and tested at the Virology Laboratory of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) and the Institute of Epidemiology, Disease Control & Research (IEDCR) tested positive for influenza A(H5) virus by reverse transcription-polymerase chain reaction (RT-PCR) on 14 August.

-- Subtyping for the N-type was pending at the time of notification. 

-- The case was detected through the Hospital-Based Influenza Surveillance (HBIS) platform. The case was discharged on 7 August.  

-- A seven-member multidisciplinary team, comprising physicians, epidemiologists, an anthropologist, and a technologist, was deployed on 15 August to conduct an investigation. 

-- The child had no history of travel and no reported exposure to backyard poultry, however the family purchased chickens from a local market in the days preceding the child’s illness. 

-- All samples collected from contacts tested negative for influenza A(H5) virus. 

-- Samples collected poultry at two markets that were frequently visited by the family of the case tested positive for influenza A(H5) virus.  

-- This is the 12th human case of avian influenza A(H5) reported to WHO from Bangladesh and the fourth in 2025. Where the genetic sequence data is available, the viruses from the human cases thus far are identified as clade 2.3.2.1a viruses. 

A(H5N1), Cambodia 

-- On 9 September 2025, Cambodia notified WHO of a laboratory-confirmed human infection with avian influenza A(H5N1) in a girl from Takeo Province. 

-- The case, with no known underlying medical conditions, had an onset of fever, cough and dyspnea on 1 September and was admitted to hospital on 5 September. Nasopharyngeal and oropharyngeal swabs collected on 7 September tested positive for avian influenza A(H5N1) at the National Institute of Public Health (NIPH) RT-PCR. 

-- Laboratory results were confirmed by the Institut Pasteur du Cambodge, National Influenza Center (NIC) on 8 September. 

-- Treatment with oseltamivir was initiated on 7 September.   

-- As part of the response, active case finding identified 10 close contacts and two villagers presenting with influenza-like illness (ILI). 

-- All nasopharyngeal and oropharyngeal samples collected from close contacts, symptomatic villagers and health workers tested negative for influenza A(H5N1) virus. 

-- A week before symptom onset, approximately 10 to 20 sick or dead chickens were observed at the case’s residence and at a neighbouring house. 

-- The case prepared and cooked sick/dead chickens. Samples collected from chickens and a duck in the village during the investigation tested positive for A(H5N1).

-- Sixteen human infections with A(H5N1) viruses have been confirmed in Cambodia in 2025 and eight of these have been fatal. All these cases in 2025 had exposure to domestic birds or their environments. In some cases, the domestic birds were reported to be sick or dead. Where the information is available, the genetic sequence data from the viruses from the human cases closely matches that from recent local animal viruses and are identified as clade 2.3.2.1e viruses. 

-- From the information available thus far on these recent human cases, there is no indication of human-to-human transmission of the A(H5N1) viruses.  

-- According to reports received by WOAH, various influenza A(H5) subtypes continue to be detected in wild and domestic birds in Africa, the Americas, Asia and Europe. 

-- Infections in non-human mammals are also reported, including in marine and land mammals.{7} 

-- A list of bird and mammalian species affected by HPAI A(H5) viruses is maintained by FAO.{8}

Risk Assessment for avian influenza A(H5) viruses:  

1. What is the current global public health risk of additional human cases of infection with avian influenza A(H5) viruses?  

-- Most human infections so far have been in people exposed to A(H5) viruses, for example, through contact with infected poultry or contaminated environments, including live poultry markets, and occasionally infected mammals and contaminated environments. 

-- As long as the viruses continue to be detected in animals and related environments humans are exposed to, further human cases associated with such exposures are expected but remain unusual. 

-- The impact for public health if additional sporadic cases are detected is minimal. 

-- The current overall global public health risk of additional sporadic human cases is low. 

2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H5) viruses related to the events above?  

-- No sustained human-to-human transmission has been identified associated with the recent reported human infections with avian influenza A(H5) viruses. 

-- There has been no reported human-to-human transmission of A(H5N1) viruses since 2007, although there may be gaps in investigations. 

-- In 2007 and the years prior, small clusters of A(H5) virus infections in humans were reported, including some involving health care workers, where limited human-to-human transmission could not be excluded; however, sustained human-to-human transmission was not reported.  

-- Current evidence suggests that influenza A(H5) viruses related to these events did not acquire the ability to efficiently transmit between people, therefore sustained human-to-human transmission is thus currently considered unlikely.  

3. What is the likelihood of international spread of avian influenza A(H5) viruses by travellers?  

-- Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. 

-- If this were to occur, further communitylevel spread is considered unlikely as current evidence suggests these viruses have not acquired the ability to transmit easily among humans.  

A(H9N2), China 

-- Since the last risk assessment of 25 August 2025, eight human cases of infection with A(H9N2) influenza viruses were notified to WHO from China between 5 and 8 September 2025. 

-- All but one of the cases were in children and were reported from Anhui (1), Chongqing (1), Guangdong (1), Guangxi (2), Hunan (1), Sichuan (1) and Tianjin (1). 

-- Four had onsets of symptoms in February and were retrospectively reported. Two had onsets in July and two had onsets in August. All but one had known exposure to either live poultry markets or backyard poultry. 

-- Five cases had mild illness and three cases developed pneumonia and were hospitalized and recovered. 

-- No further cases were detected among contacts of these cases.   

Risk Assessment for avian influenza A(H9N2):   

1. What is the global public health risk of additional human cases of infection with avian influenza A(H9N2) viruses?   

-- Most human cases follow exposure to the A(H9N2) virus through contact with infected poultry or contaminated environments. 

-- Most human infections of A(H9N2) to date have resulted in mild clinical illness. Since the virus is endemic in poultry in multiple countries in Africa and Asia{11}, further human cases associated with exposure to infected poultry are expected but remain unusual. 

-- The impact to public health if additional sporadic cases are detected is minimal. 

-- The overall global public health risk of additional sporadic human cases is low.  

2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H9N2) viruses related to this event?   

-- At the present time, no sustained human-to-human transmission has been identified associated with the recent reported human infections with A(H9N2) viruses. 

-- Current evidence suggests that influenza A(H9N2) viruses from these cases did not acquire the ability of sustained transmission among humans, therefore sustained human-to-human transmission is thus currently considered unlikely.   

3. What is the likelihood of international spread of avian influenza A(H9N2) virus by travellers?   

-- Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. 

-- If this were to occur, further community level spread is considered unlikely as current evidence suggests the A(H9N2) virus subtype has not acquired the ability to transmit easily among humans.   

Swine influenza viruses in humans  

Influenza A(H1N1)v, Germany 

Since the last risk assessment of 25 August 2025, the detection of an influenza A(H1N1)v virus in a human was reported from Germany. 

-- The virus from this case was sequenced and had an HA belonging to clade 1C.2.2, similar to other 1C.2.2 viruses detected in swine in the region. 

Risk Assessment:  

1. What is the public health risk of additional human cases of infection with swine influenza viruses?  

-- Swine influenza viruses circulate in swine populations in many regions of the world. 

-- Depending on geographic location, the genetic characteristics of these viruses differ. 

-- Most human cases are exposed to swine influenza viruses through contact with infected animals or contaminated environments. 

-- Human infection tends to result in mild clinical illness in most cases. 

-- Since these viruses continue to be detected in swine populations, further human cases are expected but remain unusual. 

-- The impact to public health if additional sporadic cases are detected is minimal. The overall risk of additional sporadic human cases is low.  

2. What is the likelihood of sustained human-to-human transmission of swine influenza viruses?   

-- No sustained human-to-human transmission was identified associated with the event described above. 

-- Current evidence suggests that contemporary swine influenza viruses have not acquired the ability of sustained transmission among humans, therefore sustained human-to-human transmission is thus currently considered unlikely.  

3. What is the likelihood of international spread of swine influenza viruses by travelers?   

-- Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. 

-- If this were to occur, further community level spread is considered unlikely as current evidence suggests that these viruses have not acquired the ability to transmit easily among humans. 

For more information on zoonotic influenza viruses, see the report from the WHO Consultation on the Composition of Influenza Virus Vaccines for Use in the 2026 Southern Hemisphere Influenza Season that was held on 22-25 September 2025 at this link. 

Overall risk management recommendations: 

-- Surveillance and investigations 

- Due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of global strategic surveillance in animals and humans to detect virologic, epidemiologic and clinical changes associated with circulating influenza viruses that may affect human (or animal) health. 

- Continued vigilance is needed within affected and neighbouring areas to detect infections in animals and humans. 

- Close collaboration with the animal health and environment sectors is essential to understand the extent of the risk of human exposure and to prevent and control the spread of animal influenza. 

- WHO has published guidance on surveillance for human infections with avian influenza A(H5) viruses. 

- As the extent of influenza virus circulation in animals is not clear, epidemiologic and virologic surveillance and the follow-up of suspected human cases should continue systematically. 

- Guidance on investigation of non-seasonal influenza and other emerging acute respiratory diseases has been published on the WHO website. 

- Countries should increase avian influenza surveillance in domestic and wild birds, enhance surveillance for early detection in cattle populations in countries where HPAI is known to be circulating, include HPAI as a differential diagnosis in non-avian species, including cattle and other livestock populations, with high risk of exposure to HPAI viruses; monitor and investigate cases in non-avian species, including livestock, report cases of HPAI in all animal species, including unusual hosts, to WOAH and other international organizations, share genetic sequences of avian influenza viruses in publicly available databases, implement preventive and early response measures to break the HPAI transmission cycle among animals through movement restrictions of infected livestock holdings and strict biosecurity measures in all holdings, employ good production and hygiene practices when handing animal products, and protect persons in contact with suspected/infected animals.9 More guidance can be found from WOAH and FAO. 

- When there has been human exposure to a known outbreak of an influenza A virus in domestic poultry, wild birds or other animals – or when there has been an identified human case of infection with such a virus – enhanced surveillance in potentially exposed human populations becomes necessary. 

- Enhanced surveillance should consider the health care seeking behaviour of the population, and could include a range of active and passive health care and/or communitybased approaches, including: enhanced surveillance in local influenza-like illness (ILI)/SARI systems, active screening in hospitals and of groups that may be at higher occupational risk of exposure, and inclusion of other sources such as traditional healers, private practitioners and private diagnostic laboratories. 

- Vigilance for the emergence of novel influenza viruses with pandemic potential should be maintained at all times including during a non-influenza emergency. In the context of the cocirculation of SARS-CoV-2 and influenza viruses, WHO has updated and published practical guidance for integrated surveillance. 

Notifying WHO 

- All human infections caused by a new subtype of influenza virus are notifiable under the International Health Regulations (IHR, 2005).{10} State Parties to the IHR (2005) are required to immediately notify WHO of any laboratory-confirmed{11} case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic{12}. 

- Evidence of illness is not required for this report. 

- WHO published the case definition for human infections with avian influenza A(H5) virus requiring notification under IHR (2005): https://www.who.int/teams/global-influenzaprogramme/avian-influenza/case-definitions. 

Virus sharing and risk assessment 

- It is critical that these influenza viruses from animals or from humans are fully characterized in appropriate animal or human health influenza reference laboratories. 

- Under WHO’s Pandemic Influenza Preparedness (PIP) Framework, Member States are expected to share influenza viruses with pandemic potential on a timely basis{13} with a WHO Collaborating Centre for influenza of GISRS. 

- The viruses are used by the public health laboratories to assess the risk of pandemic influenza and to develop candidate vaccine viruses.  

- The Tool for Influenza Pandemic Risk Assessment (TIPRA) provides an in-depth assessment of risk associated with some zoonotic influenza viruses – notably the likelihood of the virus gaining human-to-human transmissibility, and the impact should the virus gain such transmissibility. 

- TIPRA maps relative risk amongst viruses assessed using multiple elements. The results of TIPRA complement those of the risk assessment provided here, and those of prior TIPRA analyses will be published at http://www.who.int/teams/global-influenza-programme/avian-influenza/toolfor-influenza-pandemic-risk-assessment-(tipra).  

Risk reduction 

- Given the observed extent and frequency of avian influenza in poultry, wild birds and some wild and domestic mammals, the public should avoid contact with animals that are sick or dead from unknown causes, including wild animals, and should report dead birds and mammals or request their removal by contacting local wildlife or veterinary authorities.  

- Eggs, poultry meat and other poultry food products should be properly cooked and properly handled during food preparation. Due to the potential health risks to consumers, raw milk should be avoided. WHO advises consuming pasteurized milk. If pasteurized milk isn’t available, heating raw milk until it boils makes it safer for consumption. 

- WHO has published practical interim guidance to reduce the risk of infection in people exposed to avian influenza viruses. 

Trade and travellers 

- WHO advises that travellers to countries with known outbreaks of animal influenza should avoid farms, contact with animals in live animal markets, entering areas where animals may be slaughtered, or contact with any surfaces that appear to be contaminated with animal excreta. 

- Travelers should also wash their hands often with soap and water. All individuals should follow good food safety and hygiene practices.  

- WHO does not advise special traveller screening at points of entry or restrictions with regards to the current situation of influenza viruses at the human-animal interface. 

- For recommendations on safe trade in animals and related products from countries affected by these influenza viruses, refer to WOAH guidance.  

Links:  

-- WHO Human-Animal Interface web page https://www.who.int/teams/global-influenza-programme/avian-influenza 

-- WHO Influenza (Avian and other zoonotic) fact sheet https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic) 

-- WHO Protocol to investigate non-seasonal influenza and other emerging acute respiratory diseases https://www.who.int/publications/i/item/WHO-WHE-IHM-GIP-2018.2 

-- WHO Public health resource pack for countries experiencing outbreaks of influenza in animals:  https://www.who.int/publications/i/item/9789240076884 

-- Cumulative Number of Confirmed Human Cases of Avian Influenza A(H5N1) Reported to WHO  https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-a-h5n1-virus 

-- Avian Influenza A(H7N9) Information https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-influenza-a-(h7n9)virus 

-- World Organisation of Animal Health (WOAH) web page: Avian Influenza  https://www.woah.org/en/home/ 

-- Food and Agriculture Organization of the United Nations (FAO) webpage: Avian Influenza https://www.fao.org/animal-health/avian-flu-qa/en/ 

-- OFFLU http://www.offlu.org/ 

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{1} This summary and assessment covers information confirmed during this period and may include information received outside of this period. 

{2} For epidemiological and virological features of human infections with animal influenza viruses not reported in this assessment, see the reports on human cases of influenza at the human-animal interface published in the Weekly Epidemiological Record here.  

{3} World Organisation for Animal Health (WOAH). Avian influenza. Global situation. Available at: https://www.woah.org/en/disease/avian-influenza/#ui-id-2. 

{4} Food and Agriculture Organization of the United Nations (FAO). Global Avian Influenza Viruses with Zoonotic Potential situation update. Available at: https://www.fao.org/animal-health/situation-updates/global-aiv-withzoonotic-potential. 

{5} World Health Organization (2012). Rapid risk assessment of acute public health events. World Health Organization. Available at: https://iris.who.int/handle/10665/70810. 

{6} World Health Organization. Case definitions for the 4 diseases requiring notification to WHO in all circumstances under the International Health Regulations (2005). Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005).   

{7} World Organisation for Animal Health (WOAH). Avian influenza. Global situation. Available at: https://www.woah.org/en/disease/avian-influenza/#ui-id-2. 

{8} Food and Agriculture Organization of the United Nations. Global Avian Influenza Viruses with Zoonotic Potential situation update. Available at: https://www.fao.org/animal-health/situation-updates/global-aiv-withzoonotic-potential/bird-species-affected-by-h5nx-hpai/en. 

{9} World Organisation for Animal Health. Statement on High Pathogenicity Avian Influenza in Cattle, 6 December 2024. Available at: https://www.woah.org/en/high-pathogenicity-avian-influenza-hpai-in-cattle/. 

{10} World Health Organization. Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005).    

{11} World Health Organization. Manual for the laboratory diagnosis and virological surveillance of influenza (2011). Available at: https://apps.who.int/iris/handle/10665/44518 

{12} World Health Organization. Pandemic influenza preparedness framework for the sharing of influenza viruses and access to vaccines and other benefits, 2nd edition. Available at: https://iris.who.int/handle/10665/341850 

{13} World Health Organization. Operational guidance on sharing influenza viruses with human pandemic potential (IVPP) under the Pandemic Influenza Preparedness (PIP) Framework (2017). Available at: https://apps.who.int/iris/handle/10665/259402. 

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Source: World Health Organization, https://www.who.int/publications/m/item/influenza-at-the-human-animal-interface-summary-and-assessment--29-september-2025

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#Nipah virus #infection - #Bangladesh (#WHO D.O.N., September 18 '25)

 

Situation at a glance

Between 1 January and 29 August 2025, the International Health Regulations National Focal Point (IHR NFP) for Bangladesh notified WHO of four confirmed fatal Nipah virus (NiV) infection cases, temporally unrelated, reported from four different districts across three separated geographical divisions (Barisal, Dhaka, and Rajshahi) in Bangladesh. 

NiV infection is a zoonotic disease transmitted to humans through infected animals (such as bats or pigs), or food contaminated with saliva, urine, and excreta of infected animals. 

It can also be transmitted directly from person to person through close contact with an infected person. 

Fruit bats or flying foxes (Pteropus species) are the natural hosts for the virus. 

Human NiV infection is an epidemic-prone disease that can cause severe disease in humans and animals, with a high mortality rate, and outbreaks primarily occurring in South and South-East Asia. 

Since the first recognized outbreak in Bangladesh in 2001, human infections have been detected almost every year. 

To date, Bangladesh has documented 347 NiV cases through its Nipah surveillance system established to detect and respond to outbreaks promptly, with a case fatality rate of 71.7% 

There are currently no specific drugs or vaccines for NiV infection; intensive supportive care is recommended to treat severe respiratory and neurologic complications. 

Public health efforts should focus on raising awareness of risk factors, promoting preventive measures to reduce exposure to the virus, and on early case detection supported by adequate intensive supportive care. 

The Ministry of Health and Family Welfare in Bangladesh has implemented several public health measures with support from WHO. 

WHO assesses the overall public health risk posed by NiV at the national and regional levels to be moderate; the risk of international disease spread is considered low.

Description of the situation

Between 1 January and 29 August 2025, the Bangladesh IHR NFP notified WHO of four confirmed fatal Nipah virus (NiV) infection cases that occurred at different times from four separate districts across three different divisions (Barisal, Dhaka, and Rajshahi) of Bangladesh. 

All cases were confirmed through Reverse Transcription Polymerase Chain Reaction (PCR) and Enzyme-Linked Immunosorbent Assay (ELISA) testing, and no epidemiological links were reported to have been identified between the cases.

The first case was a young adult woman from Pabna district, Rajshahi division, with symptom onset on 25 January. She was admitted to a community hospital on 26 January and referred to another hospital the next day. She died on 28 January, and laboratory confirmation of NiV was received on 29 January. A total of 96 contacts were reported to be identified, and all tested negative for NiV.

The second case was an adult man from Bhola district, Barisal division, who developed symptoms on 13 February and was admitted to hospital on 19 February. He was transferred to another hospital the next day and died on 22 February. NiV infection was confirmed on 21 February. A total of 71 contacts were reportedly identified, and all tested negative for NiV.

The third case was an adult man from Faridpur district, Dhaka division, with symptom onset on 17 February. He was admitted to hospital on 25 February and died the same day. NiV infection was confirmed on 26 February. A total of 66 contacts were identified, and all tested negative for NiV.

The fourth case was a male child from Naogaon district, Rajshahi division, with symptom onset on 3 August. He was admitted to a hospital on 8 August and moved to the intensive care unit the following day. He died on 14 August. Samples collected on 10 August tested positive for NiV on 22 August. An outbreak investigation team was deployed the same day. A total of 72 contacts were identified, and samples from 11 symptomatic contacts were collected. Six tested negative, while the results for the remaining are awaited. This case was reported outside the typical season (December to April).

The first three cases had a history of consuming raw palm sap. However, the fourth case had no history of consuming raw palm sap, and the likely source/s of infection remain under investigation. None of the cases appears to be linked to each other. Fruit bats, the known reservoir for NiV, are present in the affected regions.

Since the report of the first case in 2001, human infections have been reported almost every year, with case fatality ratios (CFR) varying between 25% (in 2009) and 100% (in 2024). In 2024, five laboratory-confirmed fatal cases of NiV were reported from Bangladesh (Figure 1, Figure 2).

Figure 1. Annual number of reported Nipah virus cases and deaths, 1 January 2001 – 9 September 2025, Bangladesh.

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Source: Institute of Epidemiology, Disease Control and Research, Bangladesh. https://iedcr.portal.gov.bd/site/page/d5c87d45-b8cf-4a96-9f94-7170e017c9ce/- 

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Figure 2. Distribution of Nipah cases in Bangladesh, 2001-2025, as of 14 August 2025

Epidemiology

Nipah virus infection is a zoonotic disease transmitted to humans through infected animals (such as bats or pigs), or food contaminated with saliva, urine, and excreta of infected animals. It can also be transmitted directly from person to person through close contact with an infected person. Fruit bats or flying foxes (Pteropus species) are the natural hosts for the virus.

The incubation period ranges from 4 to 14 days. However, an incubation period of up to 45 days has once been reported. Laboratory diagnosis of a patient with a clinical history of NiV infection can be made during the acute and convalescent phases of the disease by using a combination of tests. The main tests used are RT-PCR from bodily fluids and antibody detection via ELISA.

Human infections range from asymptomatic infection to acute respiratory infection (mild, severe), and fatal encephalitis (brain swelling).

Infected people initially develop symptoms including fever, headaches, myalgia (muscle pain), vomiting and sore throat. This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis. Some people can also experience atypical pneumonia and severe respiratory problems, including acute respiratory distress. Encephalitis and seizures occur in severe cases, progressing to coma within 24 to 48 hours.

(...)

The CFR in outbreaks across Bangladesh, India, Malaysia, and Singapore range from 40% to 75%, depending on local capabilities for early detection and clinical management. There are currently no drugs or vaccines specific for NiV infection. Intensive supportive care is recommended to treat severe respiratory and neurologic complications. Henipavirus nipahense (Nipah virus) is considered a priority pathogen for the acceleration of medical countermeasures (MCMs) to respond to epidemics and pandemics as part of the WHO R&D Blueprint for Epidemics.[1]

Public health response

Several public health measures have been implemented by local authorities, including:

-- The Ministry of Health and Family Welfare has conducted investigations in collaboration with other sectors through a One Health coordinated approach.

-- Contact tracing has been carried out around the identified cases, with continuous follow-up.

-- Surveillance effort has been strengthened and extended beyond the regular active and passive surveillance to ensure early case detection.

-- Health education and awareness campaigns, including community engagement and advocacy, are ongoing under the supervision of civil surgeons (the head of the district health systems).

-- Nipah information leaflets have been distributed in endemic areas as part of risk communication efforts.

-- Clinicians have been sensitized and alerted to NiV.

-- Prompt sample collection, transportation, and testing were conducted at the reference laboratories.

The support provided by WHO:

-- Provided event communication support at national and international levels, including the timely submission of an official IHR notification to WHO.

-- Closely followed up on NiV infection field investigations to support robust data collection and effective contact tracing.

-- Supported case management, including infection prevention and control measures at household and health facility levels to prevent secondary cases.

-- Monitoring of the evolving outbreak situation, especially during the ongoing Nipah season, including support for data compilation, assessment of epidemiological patterns, risk factors, and geographic spread.

-- Provided technical support to the government in developing public health messaging for the prevention and control of the outbreak. 

WHO risk assessment

Nipah virus (Henipavirus nipahense) is a zoonotic pathogen with a high CFR (40-75%) and no licensed vaccine or treatment. Its reservoirs are fruit bats or flying foxes (bats in the Pteropus genus), which are distributed in the coastal regions and on several islands in the Indian ocean, India, south-east Asia and Oceania. The virus can be transmitted to humans from wild and domestic animals. So far, outbreaks have only been reported in Asia; however, as the disease can be transmitted by domesticated animals and secondary human-to-human transmissions are also possible, it has considerable epidemic or pandemic potential. The disease is endemic in Bangladesh, with seasonal outbreaks linked to bat activities and cultural practices such as the consumption of raw date palm sap.  Seasonal outbreaks occur between December and May, coinciding with the harvesting of date palm sap.

To date, Bangladesh has documented 347 NiV disease cases, with a case fatality rate of 71.7%. Nearly half of these cases (n=162) were primary cases with a confirmed history of consuming raw date palm sap (DPS) or tari (fermented date palm sap), while 29% resulted from direct person-to-person transmission. In 2025 to date, four fatal cases of NiV infection have been reported in Bangladesh; however, none of them appear to be linked to each other. While three of the cases presented a seasonal pattern, clustered during the first two months of 2025, the fourth case presented outside of the usual season, with no history of consuming raw date palm sap, and the possible source of infection remains unknown.

Based on the current available information, WHO assesses the overall public health risk posed by NiV at the national level to be moderate, taking into consideration the high case fatality rate, no availability of specific drugs or vaccines for NiV infection and the difficulty of early diagnosis. Although sensitive and specific laboratory methods exist, the symptoms during the first phase are not specific and could potentially delay a timely diagnosis, outbreak detection and response. In addition, fruit bats (Pteropus spp.) are the natural reservoir of NiV, and they are present in Bangladesh and repeated spillover of the virus from its reservoir to the human population has been demonstrated. Despite ongoing efforts at risk communication and community engagement to raise awareness, there is continued consumption of raw date palm sap in the community.

People infected with NiV may remain asymptomatic. Although human-to-human transmission has been reported in previous outbreaks, it has been less frequent in recent years. The yearly number of NiV infection cases reported in Bangladesh has remained under 10 since 2016, except for 2023, when 13 cases were reported.  Strong public health measures are implemented in Bangladesh to detect and control outbreaks, including sentinel NiV surveillance, established since 2006, and the availability of Rapid Response Team (RRT) at both the central and district levels, along with the capacity to rapidly test samples.

For neighbouring countries – India and Myanmar - WHO assesses the public health risk posed by NiV at the regional level to be moderate. While there has not been any report of previous cross-border transmission, the risk of spread still remains, given the shared ecological corridor of fruit bats and the occurrence among domestic animals and human cases previously reported in both countries. India has demonstrated capacity and experience in controlling previous NiV outbreaks.

WHO assesses the public health risk posed by NiV at the global level to be low, as there have been no confirmed spread of cases outside Bangladesh. 

WHO advice

In the absence of a licensed vaccine or specific therapeutic treatment for Nipah virus disease, the only way to reduce or prevent infection in people is by raising awareness of the risk factors. This includes providing guidance on measures that people can take to reduce exposure to the Nipah virus, and case management should focus on delivering timely supportive care, supported by an effective laboratory system. Intensive supportive care is recommended for treatment of severe respiratory and neurologic complications.   

Public health educational messages should focus on:

-- Reducing the risk of bat-to-human transmission

-- Efforts to prevent transmission should first focus on decreasing bat access to date palm sap and other fresh food products. Freshly collected date palm juice should be boiled, and fruits should be thoroughly washed and peeled before consumption. Fruits with signs of bat bites should be discarded. Areas where bats are known to roost should be avoided.

-- Reducing the risk of human-to-human transmission.

-- Close unprotected physical contact with NiV-infected people should be avoided. Regular hand washing should be carried out after caring for or visiting sick people.

-- Protective measures include guidelines to limit the spread of the disease both in households and hospitals (use of protective equipment, isolation, and safe contact with medical staff).

-- The options to prevent secondary transmissions are active case finding, contact tracing, isolation and quarantine of cases and their contacts.

-- Controlling infection in health care settings

-- Health and care workers caring for patients with suspected or confirmed infection, or handling specimens from them, should implement standard precautions for infection prevention and control at all times.

-- As health care-associated infections and occupational infections of Nipah virus have been reported, in health-care settings, contact and droplet precautions should be used in addition to standard precautions, including the use of single-rooms for isolation. Airborne precautions are required in addition to contact precautions during aerosol-generating procedures.

-- Enhanced environmental controls in health-care settings are advised, including twice daily environmental cleaning and disinfection of all surfaces in the patient care area of patients with suspected or confirmed NiV infection, and to ensure inpatient care areas meet or exceed the minimum ventilation rate of at least 60 litres per second per patient.

-- Samples taken from people and animals with suspected NiV infection should be handled by trained staff working in suitably equipped laboratories.

Based on the currently available information, WHO does not recommend any travel and/or trade restrictions.

Further information

-- World Health Organization. WHO South-East Asia Regional Strategy for the prevention and control of Nipah virus infection 20232030 https://www.who.int/publications/i/item/9789290210849

-- World Health Organization. Technical brief: Enhancing readiness for a Nipah virus event in countries not reporting a Nipah virus event. Interim Document, February 2024. https://www.who.int/publications/i/item/9789290211273

-- Nipah virus [Fact sheet]. Geneva: WHO; 2018. Available from: https://www.who.int/news-room/fact-sheets/detail/nipah-virus

-- World Health Organization. Nipah virus infection. https://www.who.int/health-topics/nipah-virus-infection#tab=tab_1

-- Nipah Situation Dashboard, Institute of Epidemiology, Disease Control and Research (IEDCR). https://www.iedcr.gov.bd/site/page/d5c87d45-b8cf-4a96-9f94-7170e017c9ce/-  

-- Nipah Virus Transmission in Bangladesh https://www.iedcr.gov.bd/site/page/03d6e960-2539-4966-8788-4a12753e410d/-  

-- Foodborne Transmission of Nipah Virus, Bangladesh https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291367  

-- Nipah Virus Disease: Epidemiological, Clinical, Diagnostic and Legislative Aspects of This Unpredictable Emerging Zoonosis https://www.mdpi.com/2076-2615/13/1/159

-- Tackling a global epidemic threat: Nipah surveillance in Bangladesh, 2006–2021 https://pmc.ncbi.nlm.nih.gov/articles/PMC10529576/

-- The Ecology of Nipah Virus in Bangladesh: A Nexus of Land-Use Change and Opportunistic Feeding Behaviour in Bats https://pmc.ncbi.nlm.nih.gov/articles/PMC7910977/

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[1] CEPI and WHO urge broader research strategy for countries to prepare for the next pandemic: https://www.who.int/news/item/01-08-2024-cepi-and-who-urge-broader-research-strategy-for-countries-to-prepare-for-the-next-pandemic

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Citable reference: World Health Organization (18 September 2025). Disease Outbreak News: Nipah virus infection in Bangladesh. Available at:  https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON582 

Source: World Health Organization, https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON582

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Genomic #Surveillance Detection of #SARS-CoV-1–Like Viruses in Rhinolophidae #Bats, Bandarban Region, #Bangladesh

Abstract

We sequenced sarbecovirus from Rhinolophus spp. bats in Bandarban District, Bangladesh, in a genomic surveillance campaign during 2022–2023. Sequences shared identity with SARS-CoV-1 Tor2, which caused an outbreak of human illnesses in 2003. Describing the genetic diversity and zoonotic potential of reservoir pathogens can aid in identifying sources of future spillovers.

Source: US Centers for Disease Control and Prevention, https://wwwnc.cdc.gov/eid/article/31/8/25-0071_article

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#Influenza at the #human - #animal #interface - #Summary and #risk #assessment, from 28 May to 1 July 2025 (#WHO)

 

New human cases{2}: 

-- From 28 May to 1 July 2025, based on reporting date, the detection of influenza A(H5N1) in nine humans, influenza A(H9N2) in three humans and influenza A(H10N3) in one human were reported officially. Additionally, one human case of infection with an influenza A(H5N1) virus was detected. 

Circulation of influenza viruses with zoonotic potential in animals: 

-- High pathogenicity avian influenza (HPAI) events in poultry and non-poultry continue to be reported to the World Organisation for Animal Health (WOAH).{3} The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4} 

Risk assessment{5}: 

-- Sustained human to human transmission has not been reported from these events. 

-- Based on information available at the time of the risk assessment, the overall public health risk from currently known influenza viruses circulating at the human-animal interface has not changed remains low. 

-- The occurrence of sustained human-to-human transmission of these viruses is currently considered unlikely. 

-- Although human infections with viruses of animal origin are infrequent, they are not unexpected at the human-animal interface.  

IHR compliance: 

-- All human infections caused by a new influenza subtype are required to be reported under the International Health Regulations (IHR, 2005).{6} 

-- This includes any influenza A virus that has demonstrated the capacity to infect a human and its haemagglutinin (HA) gene (or protein) is not a mutated form of those, i.e. A(H1) or A(H3), circulating widely in the human population. 

-- Information from these notifications is critical to inform risk assessments for influenza at the human-animal interface.  

Avian influenza viruses in humans 

Current situation:  

Since the last risk assessment of 27 May 2025, single laboratory-confirmed human cases of A(H5N1) infection were detected in Bangladesh and India. Eight confirmed human cases of A(H5N1) infection were reported to WHO from Cambodia. 

-- A(H5N1), Bangladesh 

On 31 May 2025, Bangladesh notified WHO of one confirmed human case of avian influenza A(H5) in a child in Chittagong division detected through hospital-based surveillance. The patient was admitted to hospital on 21 May with diarrhea, fever and mild respiratory symptoms and a respiratory sample was collected on admission. On 28 May, the IEDCR confirmed infection with avian influenza A(H5) through RT-PCR. The N-type was later confirmed as N1. The patient has recovered, and exposure to backyard poultry was reported prior to symptom onset. No further cases were detected among the contacts of the case. This is the 11th human infection with influenza A(H5N1) notified to WHO from Bangladesh since the first case was reported in the Dhaka division in 2008 and the third confirmed case in 2025. 

-- A(H5N1), Cambodia 

Between 29 May and 1 July 2025, Cambodia notified WHO of eight laboratory-confirmed cases of A(H5N1) virus infection.  

(...)

All cases above had exposure to sick or dead backyard poultry. The most recent case was from a different village than the other three cases from Siem Reap. The 46-year-old female and the 16-yearold male cases are members of the same family and are neighbors of the first case detected in Siem Reap; they were sampled as part of active case finding during the response to the first case because they also handled sick and dead poultry from their own backyard. 

Rapid response teams from the public health and animal health sectors have been deployed to investigate and respond to the outbreak.  

Eleven human infections with A(H5N1) viruses have been confirmed in Cambodia in 2025 and six of these have been fatal. 

All these cases in 2025 had exposure to domestic birds or their environments. In some cases, the domestic birds were reported to be sick or dead. 

Influenza A(H5N1) viruses continue to be detected in domestic birds in Cambodia in 2025, including in areas where human cases have been detected.{7} 

Where the information is available, the genetic sequence data from the viruses from the human cases closely matches that from recent local animal viruses and are identified as clade 2.3.2.1e viruses. From the information available thus far on these recent human cases, there is no indication of human-to-human transmission of the A(H5N1) viruses.  

-- A(H5N1), India  

A human infection with an H5 clade 2.3.2.1a A(H5N1) virus was detected in a sample collected from a man in Khulna state in May 2025, who subsequently died. Genetic sequence data are available in GISAID (EPI_ISL_19893416; submission date 4 June 2025; ICMR-National Institute of Virology; Influenza). 

According to reports received by WOAH, various influenza A(H5) subtypes continue to be detected in wild and domestic birds in Africa, the Americas, Asia and Europe. 

Infections in non-human mammals are also reported, including in marine and land mammals.{8} A list of bird and mammalian species affected by HPAI A(H5) viruses is maintained by FAO.{9}    

Risk Assessment for avian influenza A(H5N1) viruses:  

1. What is the current global public health risk of additional human cases of infection with avian influenza A(H5N1) viruses?  

-- Most human cases so far have been infections in people exposed to A(H5) viruses, for example, through contact with infected poultry or contaminated environments, including live poultry markets, and occasionally infected mammals and contaminated environments. While the viruses continue to be detected in animals and related environments humans are exposed to, further human cases associated with such exposures are expected but unusual. The impact for public health if additional cases are detected is minimal. The current overall global public health risk of additional human cases is low. 

2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H5N1) viruses related to the events above?  

No sustained human-to-human transmission has been identified associated with the recent reported human infections with avian influenza A(H5N1) viruses. There has been no reported human-tohuman transmission of A(H5N1) viruses since 2007, although there may be gaps in investigations. In 2007 and the years prior, small clusters of A(H5) virus infections in humans were reported, including some involving health care workers, where limited human-to-human transmission could not be excluded; however, sustained human-to-human transmission was not reported.  Current evidence suggests that influenza A(H5N1) viruses related to these events did not acquire the ability to efficiently transmit between people, therefore the likelihood of sustained human-tohuman transmission is thus currently considered unlikely.  

3. What is the likelihood of international spread of avian influenza A(H5N1) viruses by travellers?  

Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. If this were to occur, further community-level spread is considered unlikely as current evidence suggests these viruses have not acquired the ability to transmit easily among humans.  

-- A(H9N2), China

Since the last risk assessment of 27 May 2025, three human cases of infection with A(H9N2) influenza viruses were notified to WHO from China on 9 June 2025. The cases were detected in Henan, Hunan and Sichuan provinces. Two infections were detected in adults who were also hospitalized. The cases had symptom onset in May 2025 and have recovered. All cases had a known history of exposure to poultry prior to the onset of symptoms. No further cases were detected among contacts of these cases and there was no epidemiological link between the cases.   

Risk Assessment for avian influenza A(H9N2):   

1. What is the global public health risk of additional human cases of infection with avian influenza A(H9N2) viruses?   

Most human cases follow exposure to the A(H9N2) virus through contact with infected poultry or contaminated environments. Most human infections of A(H9N2) to date have resulted in mild clinical illness. Since the virus is endemic in poultry in multiple countries in Africa and Asia{11}, further human cases associated with exposure to infected poultry are expected but remain unusual. The impact to public health if additional cases are detected is minimal. The overall global public health risk of additional human cases is low.  

2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H9N2) viruses related to this event?   

At the present time, no sustained human-to-human transmission has been identified associated with the recent reported human infections with A(H9N2) viruses. Current evidence suggests that influenza A(H9N2) viruses from these cases did not acquire the ability of sustained transmission among humans, therefore sustained human-to-human transmission is thus currently considered unlikely.   

3. What is the likelihood of international spread of avian influenza A(H9N2) virus by travellers?   

Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. If this were to occur, further community level spread is considered unlikely as current evidence suggests the A(H9N2) virus subtype has not acquired the ability to transmit easily among humans.   

-- A(H10N3), China  

On 9 June 2025, China notified the WHO of one confirmed case of human infection with avian influenza A(H10N3) virus in an adult from Shaanxi Province, with a history of asthma. Symptom onset occurred on 21 April, and the patient was admitted to hospital with pneumonia on 25 April. At the time of reporting, that patient was under treatment and improving.    According to the epidemiological investigation, a history of exposure to backyard poultry in Inner Mongolia was reported. The patient is a farmer and raises chickens and sheep. Environmental samples did not test positive for influenza A(H10) viruses. All close contacts tested negative for influenza A and remained asymptomatic during the monitoring period.    Since 2021, China has notified WHO of a total of six confirmed human cases of avian influenza A(H10N3) virus infection. 

Risk Assessment for avian influenza A(H10N3):   

1. What is the global public health risk of additional human cases of infection with avian influenza A(H10N3) viruses?   

Human infections with avian influenza A(H10) viruses have been detected and reported previously.   The circulation and epidemiology of these viruses in birds have been previously reported.{12} Avian influenza A(H10N3) viruses with different genetic characteristics have been detected previously in wild birds since the 1970s and more recently spilled over to poultry in some countries. As long as the virus continues to circulate in birds, further human cases can be expected but remain unusual. The impact to public health if additional sporadic cases are detected is minimal. The overall global public health risk of additional sporadic human cases is low.    

2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H10N3) viruses related to this event?   

No sustained human-to-human transmission has been identified associated with the event described above or past events with human cases of influenza A(H10N3) viruses. Current epidemiologic and virologic evidence suggests that influenza A(H10N3) viruses related to this event did not acquire the ability of sustained transmission among humans, therefore sustained human-tohuman transmission is thus currently considered unlikely.    

3. What is the likelihood of international spread of avian influenza A(H10N3) virus by travellers?   

Should infected individuals from affected areas travel internationally, their infection may be   detected in another country during travel or after arrival. If this were to occur, further community   level spread is considered unlikely based on current limited evidence.   

Overall risk management recommendations: 

Surveillance and investigations 

• Due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of global strategic surveillance in animals and humans to detect virologic, epidemiologic and clinical changes associated with circulating influenza viruses that may affect human (or animal) health. Continued vigilance is needed within affected and neighbouring areas to detect infections in animals and humans. Close collaboration with the animal health and environment sectors is essential to understand the extent of the risk of human exposure and to prevent and control the spread of animal influenza. WHO has published guidance on surveillance for human infections with avian influenza A(H5) viruses. 

• As the extent of influenza virus circulation in animals is not clear, epidemiologic and virologic surveillance and the follow-up of suspected human cases should continue systematically. Guidance on investigation of non-seasonal influenza and other emerging acute respiratory diseases has been published on the WHO website. 

• Countries should increase avian influenza surveillance in domestic and wild birds, enhance surveillance for early detection in cattle populations in countries where HPAI is known to be circulating, include HPAI as a differential diagnosis in non-avian species, including cattle and other livestock populations, with high risk of exposure to HPAI viruses; monitor and investigate cases in non-avian species, including livestock, report cases of HPAI in all animal species, including unusual hosts, to WOAH and other international organizations, share genetic sequences of avian influenza viruses in publicly available databases, implement preventive and early response measures to break the HPAI transmission cycle among animals through movement restrictions of infected livestock holdings and strict biosecurity measures in all holdings, employ good production and hygiene practices when handing animal products, and protect persons in contact with suspected/infected animals.{10}  

• When there has been human exposure to a known outbreak of an influenza A virus in domestic poultry, wild birds or other animals – or when there has been an identified human case of infection with such a virus – enhanced surveillance in potentially exposed human populations becomes necessary. Enhanced surveillance should consider the health care seeking behaviour of the population, and could include a range of active and passive health care and/or community-based approaches, including: enhanced surveillance in local influenza-like illness (ILI)/SARI systems, active screening in hospitals and of groups that may be at higher occupational risk of exposure, and inclusion of other sources such as traditional healers, private practitioners and private diagnostic laboratories. 

• Vigilance for the emergence of novel influenza viruses of pandemic potential should be maintained at all times including during a non-influenza emergency. In the context of the cocirculation of SARS-CoV-2 and influenza viruses, WHO has updated and published practical guidance for integrated surveillance. 

Notifying WHO 

• All human infections caused by a new subtype of influenza virus are notifiable under the International Health Regulations (IHR, 2005).{11} State Parties to the IHR (2005) are required to immediately notify WHO of any laboratory-confirmed{12} case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic{13}. Evidence of illness is not required for this report. 

• WHO published the case definition for human infections with avian influenza A(H5) virus requiring notification under IHR (2005): https://www.who.int/teams/global-influenzaprogramme/avian-influenza/case-definitions. 

Virus sharing and risk assessment 

• It is critical that these influenza viruses from animals or from people are fully characterized in appropriate animal or human health influenza reference laboratories. Under WHO’s Pandemic Influenza Preparedness (PIP) Framework, Member States are expected to share influenza viruses with pandemic potential on a timely basis{14} with a WHO Collaborating Centre for influenza of GISRS. The viruses are used by the public health laboratories to assess the risk of pandemic influenza and to develop candidate vaccine viruses.  

• The Tool for Influenza Pandemic Risk Assessment (TIPRA) provides an in-depth assessment of risk associated with some zoonotic influenza viruses – notably the likelihood of the virus gaining human-to-human transmissibility, and the impact should the virus gain such transmissibility. TIPRA maps relative risk amongst viruses assessed using multiple elements. The results of TIPRA complement those of the risk assessment provided here, and those of prior TIPRA analyses will be published at http://www.who.int/teams/global-influenza-programme/avian-influenza/toolfor-influenza-pandemic-risk-assessment-(tipra).  

Risk reduction 

• Given the observed extent and frequency of avian influenza in poultry, wild birds and some wild and domestic mammals, the public should avoid contact with animals that are sick or dead from unknown causes, including wild animals, and should report dead birds and mammals or request their removal by contacting local wildlife or veterinary authorities.  

• Eggs, poultry meat and other poultry food products should be properly cooked and properly handled during food preparation. Due to the potential health risks to consumers, raw milk should be avoided. WHO advises consuming pasteurized milk. If pasteurized milk isn’t available, heating raw milk until it boils makes it safer for consumption. 

WHO has published practical interim guidance to reduce the risk of infection in people exposed to avian influenza viruses. 

Trade and travellers 

• WHO advises that travellers to countries with known outbreaks of animal influenza should avoid farms, contact with animals in live animal markets, entering areas where animals may be slaughtered, or contact with any surfaces that appear to be contaminated with animal excreta. Travelers should also wash their hands often with soap and water. All individuals should follow good food safety and hygiene practices.  

• WHO does not advise special traveller screening at points of entry or restrictions with regards to the current situation of influenza viruses at the human-animal interface. For recommendations on safe trade in animals and related products from countries affected by these influenza viruses, refer to WOAH guidance.  

Links:  

-- WHO Human-Animal Interface web page https://www.who.int/teams/global-influenza-programme/avian-influenza 

-- WHO Influenza (Avian and other zoonotic) fact sheet https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic) 

-- WHO Protocol to investigate non-seasonal influenza and other emerging acute respiratory diseases https://www.who.int/publications/i/item/WHO-WHE-IHM-GIP-2018.2 

-- WHO Public health resource pack for countries experiencing outbreaks of influenza in animals:  https://www.who.int/publications/i/item/9789240076884 

-- Cumulative Number of Confirmed Human Cases of Avian Influenza A(H5N1) Reported to WHO  https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-a-h5n1-virus 

-- Avian Influenza A(H7N9) Information https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-influenza-a-(h7n9)virus 

-- World Organisation of Animal Health (WOAH) web page: Avian Influenza  https://www.woah.org/en/home/ 

-- Food and Agriculture Organization of the United Nations (FAO) webpage: Avian Influenza https://www.fao.org/animal-health/avian-flu-qa/en/ 

-- OFFLU http://www.offlu.org/ 

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{1} This summary and assessment covers information confirmed during this period and may include information received outside of this period. 

{2} For epidemiological and virological features of human infections with animal influenza viruses not reported in this assessment, see the reports on human cases of influenza at the human-animal interface published in the Weekly Epidemiological Record here.  

{3} World Organisation for Animal Health (WOAH). Avian influenza. Global situation. Available at: https://www.woah.org/en/disease/avian-influenza/#ui-id-2. 

{4} Food and Agriculture Organization of the United Nations (FAO). Global Avian Influenza Viruses with Zoonotic Potential situation update. Available at: https://www.fao.org/animal-health/situation-updates/global-aiv-withzoonotic-potential. 

{5} World Health Organization (2012). Rapid risk assessment of acute public health events. World Health Organization. Available at: https://iris.who.int/handle/10665/70810. 

{6} World Health Organization. Case definitions for the 4 diseases requiring notification to WHO in all circumstances under the International Health Regulations (2005). Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005).   

{7} https://wahis.woah.org/#/in-event/5754/dashboard 

{8} World Organisation for Animal Health (WOAH). Avian influenza. Global situation. Available at: https://www.woah.org/en/disease/avian-influenza/#ui-id-2. 

{9} Food and Agriculture Organization of the United Nations. Global Avian Influenza Viruses with Zoonotic Potential situation update. Available at: https://www.fao.org/animal-health/situation-updates/global-aiv-withzoonotic-potential/bird-species-affected-by-h5nx-hpai/en. 

{10} World Organisation for Animal Health. Statement on High Pathogenicity Avian Influenza in Cattle, 6 December 2024. Available at: https://www.woah.org/en/high-pathogenicity-avian-influenza-hpai-in-cattle/. 

{11} World Health Organization. Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005).    

{12} World Health Organization. Manual for the laboratory diagnosis and virological surveillance of influenza (2011). Available at: https://apps.who.int/iris/handle/10665/44518 

{13} World Health Organization. Pandemic influenza preparedness framework for the sharing of influenza viruses and access to vaccines and other benefits, 2nd edition. Available at: https://iris.who.int/handle/10665/341850 

{14} World Health Organization. Operational guidance on sharing influenza viruses with human pandemic potential (IVPP) under the Pandemic Influenza Preparedness (PIP) Framework (2017). Available at: https://apps.who.int/iris/handle/10665/25940 

Source: World Health Organization, https://www.who.int/publications/m/item/influenza-at-the-human-animal-interface-summary-and-assessment--1-july-2025

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