Heterologous Sequential #mRNA #Vaccination of Indian Rhesus #Macaques Elicits Broad Binding and Neutralizing #Antibody Responses Against Diverse #Henipaviruses

 

Abstract

Henipaviruses (HNVs), including Nipah virus (NiV) and Hendra virus (HeV), are highly pathogenic and often lethal zoonotic viruses with broad species tropism and no approved human vaccines. The emergence of genetically divergent HNVs—including Ghana virus (GhV), Langya virus (LayV), and Mojiang virus (MojV)—emphasizes the need for broadly protective countermeasures. Here, we evaluated the antibody (Ab) responses to sequential mRNA vaccines encoding the membrane-bound attachment glycoprotein (gG) from NiV, GhV, and/or LayV in a pilot study with Indian rhesus macaques. Serum binding Ab responses were quantified by ELISA against five soluble gG antigens (NiV, HeV, GhV, LayV, MojV). Functional activity was assessed by neutralization assays using NiV, HeV, and GhV pseudoviruses, and by receptor-blocking ELISA. Sequential vaccination induced high-titer IgG binding against all five HNV gGs with increasing breadth after each dose. Pan-genus regimens elicited moderate neutralizing Ab titers against NiV, HeV, and GhV, whereas the NiV-only regimen elicited potent but narrow neutralization against NiV and HeV. Conversely, the GhV-LayV-GhV regimen elicited strong binding to GhV, LayV, and MojV gG and robust neutralization of GhV pseudovirus, but limited cross-reactivity to NiV and HeV. In this pilot study, we demonstrated that mRNA vaccination can elicit broadly reactive binding and neutralizing Ab responses across phylogenetically distant HNVs. Additionally, we show GhV pseudovirus neutralization for the first time. Collectively, these data provide a foundation for the development of next-generation pan-genus HNV vaccines capable of mitigating future HNV outbreaks.

Source: 

Link: https://www.mdpi.com/1999-4915/18/5/487

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#Nipah virus molecular #detection from whole #blood and respiratory #swabs in a rapid field-ready protocol

 

Highlights

• A Nipah virus real-time RT-PCR was developed for this study and display dynamic amplification, with sensitive (limit of detection 3.7-4.2 copies/µL) and specific detection.

• The assay was adapted for use on a portable, battery-powered real-time thermocycler.

• When paired with instrument-free RNA extraction, Nipah virus RNA was rapidly detected from contrived whole blood and nasopharyngeal swabs without electricity.

• The combined of Extract & Store and the Palm PCR S1e device offers a viable solution for field-based molecular detection of Nipah virus.

Abstract

Background

Nipah virus (NiV) is a highly pathogenic, zoonotic paramyxovirus with significant public health implications due to high associated mortality and potential for human-to-human transmission. Current diagnostic testing options for NiV are limited and require extensive laboratory infrastructure.

Objective

Develop a field-deployable testing workflow for timely NiV detection.

Study design

A NiV real-time RT-PCR (rRT-PCR) was designed for a highly conserved region of the nucleocapsid gene and tested with RNA from Bangladesh and Malaysia NiV strains. The NiV rRT-PCR was evaluated on Rotor-Gene Q and Palm PCR S1e thermocyclers following instrument free RNA extraction (Extract & Store).

Results

Initial analytical evaluation, on a Rotor-Gene Q, demonstrated dynamic amplification and a limit of detection (LoD) of 3.7-4.2 copies/µL without amplification of related paramyxoviruses. The assay was adapted for the portable, battery-powered, self-contained Palm PCR S1e thermocycler, and exhibited linear detection with a LoD of 30.7 copies/µL. RNA extraction from contrived whole blood and pharyngeal swabs using the Extract & Store workflow yielded comparable results to automated extraction on a KingFisher Apex instrument. The entire assay, including extracted and stabilized RNA controls from BSL-1 strains, was successfully transferred to Aga Khan University with ambient temperature shipping and yielded similar performance.

Conclusions

The combination of Extract & Store and the Palm PCR S1e device offers a viable solution for field-based molecular detection of NiV. While limitations were noted for reaction setup on the Palm PCR, this presents a flexible and accessible workflow for rapid, portable detection of high-consequence pathogens in resource-constrained settings.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S138665322600020X?dgcid=rss_sd_all

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Rapid #Risk #Assessment, Acute Event of Potential Public Health Concern: #Nipah Virus #Infection - Global (#WHO, Mar. 6 '26, summary)

 

{Summary}

Risk Statement  

-- This Rapid Risk Assessment (RRA) evaluates the global public health risk posed by Nipah virus (NiV), considering the distinct epidemiological profiles of 

- i) enzootic countries, where recurrent zoonotic spillover and limited human‑to‑human transmission continue to occur, and 

- ii) non‑enzootic regions, where the risk remains primarily associated with infected travellers or importation of infected livestock. 

-- The assessment considers the ecological and seasonal drivers of spillover, the constrained efficiency of human‑to‑human transmission, and the capacity of health and community systems to detect, confirm, and rapidly contain outbreaks. 

-- Given that NiV has not demonstrated sustained transmission beyond outbreak settings and no human cases have ever been reported outside Asia, the global risk is largely determined by localized outbreaks in endemic areas and the very low likelihood of onward transmission following importation. 

-- NiV activity remains geographically limited, with human cases occurring primarily in the South-East Asia Region with limited outbreaks in the Western Pacific Region. 

-- The epidemiological profile of NiV is characterized by low frequency, localized outbreaks, occurring predominantly in Bangladesh and India, with additional historical events reported in Malaysia, Singapore, and the Philippines. 

-- Bangladesh has reported sporadic cases almost annually since 2001, largely associated with consumption of raw date palm sap, following a well‑defined seasonal pattern between December and April. 

-- India reported its first outbreak in 2001 and has documented near-annual cases in Kerala since 2018 with sporadic cases reported in West Bengal. 

-- In 2025, eight laboratory‑confirmed cases were detected across Bangladesh (four) and India (four). 

-- As of March 2026, three sporadic cases have been reported in the two countries, two in India and one in Bangladesh. 

-- Malaysia (1998–1999), Singapore (1999), and the Philippines (2014) experienced outbreaks previously but have not reported any additional NiV events recently. 

-- Although NiV has a high case‑fatality ratio (40–75%), transmission remains limited in scale, typically arising from isolated spillover events linked to fruit bats, contaminated fruits or fruit products, or occasionally infected livestock. 

-- Human‑to‑human transmission has been documented, particularly in Bangladesh and India. However, sustained community transmission or multi‑country spread has never been observed. 

KEY RISK FACTORS 

{1.} Risk to Enzootic Countries  

• Sporadic zoonotic spillover events occur due to contact with infected bats or consumption of contaminated fruits or fruit products.  

• Serological evidence of NiV circulation beyond affected areas in Bangladesh and India (Kerala and West Bengal), suggest that spillover could potentially occur in other areas where infected bats are present. 

• Human‑to‑human transmission, although documented, is limited to close contacts and has not resulted in widespread community transmission. 

• The case‑fatality ratio is high; however, the total number of reported cases remains low. 

• Health care settings may amplify transmission when infection prevention and control (IPC) measures are insufficient.  

• Spillover from other susceptible animal hosts (pigs, horses) cannot be ruled out, nor the risk of importation through infected livestock, though probably very low.  

{2.} Risk to Non‑Enzootic Regions (reservoirs may be present; no human cases to date) 

• Risk is primarily associated with an infected traveller. 

• No human NiV transmission has ever been reported outside affected Asian countries. 

• In settings without established animal reservoirs or intermediate hosts, onward transmission following importation is unlikely and would require close, prolonged contact. 

• Historical spread via movement of infected animals (e.g., pigs exported from Malaysia to Singapore in 1999) demonstrates that animal trade–related spillover is possible, however current evidence suggests that the risk under present animal‑health and trade practices is likely very low.  

{3.} Risk to Countries Without Known Bat Reservoirs (reservoirs absent; no human cases) 

• Importation via travellers (and, exceptionally, livestock) may occur and while secondary transmission is possible it is unlikely, given the absence of established animal reservoirs and the need for close contact for human‑to‑human spread. 

{4.} Risk to Travellers 

• Travellers to affected areas face a very low but non‑zero risk, particularly if they have direct exposure to fruit bats, consume contaminated food products, or come into contact with other infected animals, including pigs or horses. 

• Returning infected travellers pose a limited risk of onward transmission due to low NiV transmissibility. 

{5.} Risk Determinants 

• Ecological presence of Pteropodidae bats in enzootic countries.  

• Presence of potential intermediary hosts that could transmit to humans (e.g., pigs, horses).  

• Cultural and dietary practices (e.g., consumption of raw date palm sap). 

• Exposure in health care settings with inadequate IPC measures. 

• Limited awareness among communities and health workers. 

• Close, unprotected contact with sick/deceased individuals, including local practice traditions. 

{6.} Response Capacity 

• Countries with recurring outbreaks have strengthened their surveillance systems, diagnostics, and clinical management capacity. 

• No licensed vaccines or specific antiviral treatments are currently available; however, several vaccine and therapeutics candidates are in development, supported by CEPI and WHO‑aligned research priorities.  

• Rapid case isolation and contact tracing remain effective measures in preventing wider spread. 

{7.} Confidence in Available Information 

-- Overall confidence is moderate, due to: 

• Under‑detection of sporadic spillover events in rural areas. 

• Ongoing uncertainty about the full geographic distribution of bat reservoirs and potential intermediate hosts.  

-- Based on current evidence, characterized by rare outbreaks, limited human‑to‑human transmission, no sustained global spread, and improving response capacity, the overall global public health risk posed by NiV is assessed as Low with a Moderate level of confidence in the available information.  

-- This rapid risk assessment will be updated as new epidemiological, clinical, or virological information becomes available. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---nipah-virus---global---version-1

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Functional and #antigenic constraints on the #Nipah virus #fusion protein

 

Abstract

Nipah virus is a highly pathogenic virus in the family Paramyxoviridae that utilizes two distinct surface glycoproteins to infect cells. The receptor-binding protein (RBP) binds host receptors whereas the fusion protein (F) merges viral and host membranes. Here, we use nonreplicative pseudoviruses to safely measure the effects of all F single amino acid residue mutations on its cell entry function and neutralization by monoclonal antibodies. We compare mutational tolerance in F with previous experimental measurements for RBP and show that F is much more functionally constrained than the RBP. We also identify mutationally intolerant sites on the F trimer surface and core that are critical for proper function, and describe mutations that are candidates for stabilizing F in the prefusion conformation for vaccine design. We quantify how F mutations affect neutralization by six monoclonal antibodies, and show that the magnitude of mutational effects on neutralization varies among antibodies. Our measurements of mutational effects on Nipah virus F predict the ability of the antibodies to neutralize the related Hendra virus. Overall, our work defines the functional and antigenic constraints on the F protein from an important zoonotic virus.

Source: 

Link: https://www.pnas.org/doi/abs/10.1073/pnas.2529505123?af=R

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#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

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#Nipah virus infection - #India (#WHO D.O.N., Jan. 30 '26)

 

Situation at a glance

On 26 January 2026, the National IHR Focal Point for India notified WHO of two laboratory‑confirmed cases of Nipah virus (NiV) infection in West Bengal State. 

Both are healthcare workers at the same private hospital in Barasat (North 24 Parganas district). 

NiV infection was confirmed at the National Institute of Virology in Pune on 13 January. 

One case remains on mechanical ventilation as of 21 January, the other case experienced severe neurological illness but has since improved. 

Authorities have identified and tested over 190 contacts, who all tested negative for NiV with support from a mobile BSL‑3 laboratory deployed by the National Institute of Virology, Pune. 

No further cases have been detected to date. 

This event represents the third NiV infection outbreak reported in West Bengal (previous outbreaks reported in Siliguri in 2001 and Nadia in 2007). 

Enhanced surveillance and infection prevention and control (IPC) measures are in place while investigations into the source of exposure are ongoing. 

NiV infection is a serious but rare 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. 

There are currently no licensed medicines or vaccines for NiV infection, however early supportive care can improve survival. 

WHO assesses the risk posed by Nipah to be moderate at the sub-national level, and low at the national, the regional and global levels.

Description of the situation

On 26 January 2026, the India IHR NFP notified WHO of two confirmed NiV infection cases that occurred in West Bengal State. 

Preliminary laboratory testing suggested NiV infection, and confirmation was received from the National Institute of Virology, Pune on 13 January 2026.

The cases were confirmed through Reverse Transcription Polymerase Chain Reaction (RT-PCR) and Enzyme-Linked Immunosorbent Assay (ELISA) testing.

The first case is a female nurse and the second case is a male nurse. 

Both cases were between 20 – 30 years old, from Barasat, North 24 Parganas district. 

Both cases developed symptoms typical of severe NiV infection in late December 2025 and were admitted to hospital in early January 2026. 

As of 21 January 2026, the second case showed clinical improvement, while the first case remained under critical care.

Following the two confirmed cases, Indian health authorities identified and tested over 190 contact persons, including health and care workers and community contacts. All samples from contact persons tested negative for NiV.

The Indian National Centre for Disease Control, announced on 27 January that no further confirmed cases have been detected in West Bengal from December 2025 to date.

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 or 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 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.

Further information about NiV infection can be found here.

The case fatality ratio (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 licensed medicines 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. 

Public health response

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

-- The Government of India, in close coordination with the Government of West Bengal, initiated prompt and comprehensive public health measures in accordance with established protocols.

-- Investigations were conducted 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 efforts have been strengthened and enhanced to ensure early case detection.

-- Health education and awareness campaigns, including community engagement and advocacy, are ongoing.

-- Clinicians have been sensitized and alerted to NiV. Infection prevention and control has been strengthened at health-care settings.

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

The support provided by WHO includes:

-- Providing event communication support at national and international levels, including the submission of an official IHR notification.

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

WHO risk assessment

Nipah virus (Henipavirus nipahense) is a rare 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, however, as the disease can be transmitted by domesticated 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 India, 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.

This event represents the 13th Nipah outbreak documented in India and the third reported in West Bengal. 

Since 2001, India has reported 12 Nipah outbreaks prior to this event: 10 in the state of Kerala and two in the state of West Bengal. 

In West Bengal, previous outbreaks occurred in 2001 (Siliguri) and 2007 (Nadia district). 

Based on the current available information, WHO assesses the overall public health risk posed by NiV at the sub-national level to be moderate, taking into consideration 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 India and repeated spillover of the virus from its reservoir to the human population has been demonstrated.

Human-to-human transmission has been documented in previous outbreaks, mostly reported in health-care settings and among family and caregivers of sick people through close contact with bodily fluids. 

Implementation of adequate infection prevention and control measures in health care facilities is critical to mitigate health care associated infection.

The yearly number of NiV infection cases reported in India has remained relatively low since 2001, except for 2001, when 66 cases were reported and 2018 when 18 cases were reported. 

Over the past 5 years, a dozen confirmed cases were reported in India, all in Kerala State. 

Strong public health measures are implemented in India to detect and control outbreaks, including established NiV surveillance, and the availability of Rapid Response Teams (RRT) at both the Central and State levels, along with the capacity to rapidly test samples.

For neighbouring countries, WHO assesses the public health risk posed by NiV at the regional level to be low. There have been no reports of cross‑border transmission, and the current outbreak remains geographically limited. 

Nevertheless, the risk of disease occurrence persists due to the shared ecological corridor of fruit bats and the history of human cases previously reported in the region. India has demonstrated strong capacity and experience in managing past NiV outbreaks.

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

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. This is also important in the context of mass gatherings, where attendees come from different countries and may be unfamiliar with disease and its mode of transmission, as well as actions they can take to protect themselves. and 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

-- World Health Organization. Nipah virus [Fact sheet]. Geneva: WHO; 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/nipah-virus

-- Ministry of Health and Family Welfare. Only Two Nipah Virus Disease Cases Reported in West Bengal Since Last December: NCDC. 196 Contacts Linked to Nipah Cases Traced and Found Asymptomatic; All Test Negative. https://www.pib.gov.in/PressReleasePage.aspx?PRID=2219219&reg=3&lang=1

-- News On AIR. West Bengal reports two suspected Nipah cases; Centre sends response team. New Delhi: Prasar Bharati; 13 January 2026. Available from: https://www.newsonair.gov.in/west-bengal-reports-two-suspected-nipah-cases-centre-sends-response-team/

-- News On AIR. Centre deploys National Joint Outbreak Response Team in West Bengal after suspected Nipah cases. New Delhi: Prasar Bharati; 12 January 2026. Available from: https://www.newsonair.gov.in/centre-deploys-national-joint-outbreak-response-team-in-west-bengal-after-suspected-nipah-cases/

-- Ministry of Health and Family Welfare (MoHFW). X (formerly Twitter). 11 Jan 2026. Available from: https://x.com/MoHFW_INDIA/status/2010751351232594216

-- World Health Organization, Regional Office for South-East Asia, Epidemiological Bulletin WHO Health Emergencies Programme, 2nd edition (2026), 28 January 2026 Reporting period: 12 to 25 Jan 2026: https://cdn.who.int/media/docs/default-source/searo/whe/wherepib/2026_02_searo_epi_bulletin.pdf

-- World Health Organization (6 August 2025). Disease Outbreak News; Nipah virus infection – India. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON577

-- https://www.who.int/news-room/fact-sheets/detail/nipah-virus

-- World Health Organization, Regional Office for South-East Asia. Regional strategy for the prevention and control of Nipah virus infection: 2023–2030. New Delhi: WHO SEARO; 2023. Available from: 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. Geneva: WHO; 2024 Feb. Available from: https://www.who.int/publications/i/item/9789290211273

-- Kumar SS, Maan S, Kumari M, Gupta P, Bhatia S, Maan NS. Nipah virus disease: epidemiological, clinical, diagnostic and legislative aspects of this unpredictable emerging zoonosis. Animals (Basel). 2023;13(1):159. doi:10.3390/ani13010159. Available from: https://www.mdpi.com/2076-2615/13/1/159

-- Thomas B, Chandran P, Lilabi MP, George B, Sivakumar CP, Jayadev VK, et al. Nipah virus infection in Kozhikode, Kerala, South India, in 2018: epidemiology of an outbreak of an emerging disease. Indian J Community Med. 2019;44(4):383–7. https://pubmed.ncbi.nlm.nih.gov/31802805

-- World Health Organization. Standard precautions for the prevention and control of infections: aide memoire. Geneva: WHO; 2022. Available from: https://www.who.int/publications/i/item/WHO-UHL-IHS-IPC-2022.1

-- Transmission-based precautions for the prevention and control of infections: aide memoire. Geneva: WHO; 2022. Available from: https://www.who.int/publications/i/item/WHO-UHL-IHS-IPC-2022.2

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON593

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#HK, DH follows up on #Nipah virus #infection cluster in #India (Jan. 26 '26)

 

DH follows up on Nipah virus infection cluster in India

In light of reports indicating a cluster of a Nipah virus infection in a certain region of India, the Centre for Health Protection (CHP) of the Department of Health (DH) said today (January 26) that it has proactively sought further information from the World Health Organization (WHO) and Indian health authorities. 

The CHP is also conducting health screenings on inbound travellers from the affected area who exhibit suspected symptoms, with an aim of promptly referring suspected cases to hospitals for investigation. 

Currently, there are no imported or local cases of Nipah virus infection in Hong Kong.

Preliminary information indicated that a hospital in Kolkata, West Bengal, India, has recorded five confirmed cases of Nipah virus infection since mid-January of this year. 

The cluster was mainly due to nosocomial transmission and primarily involved healthcare workers, with no reported deaths or cross-border transmissions to date. 

Approximately 100 close contacts have been quarantined and tested in India. 

The CHP's current risk assessment indicates a low risk of importation of Nipah virus into Hong Kong.

Nipah virus was first identified during outbreaks in Malaysia and Singapore from 1998 to 1999, affecting pig farm workers and individuals with close contact with pigs. 

It can affect various animals, including pigs, horses, goats, sheep, cats and dogs. 

Over the past two decades, multiple outbreaks of human Nipah virus infections were recorded in Bangladesh and India, typically occurring between December and April. 

Transmission primarily occurs through the consumption of raw date palm sap contaminated by fruit bats. India's most recent outbreak occurred in Kerala in mid-2025, involving four cases.

"Nipah virus infection is an emerging zoonotic disease. Fruit bats are the natural host for the virus. The virus is mainly transmitted through direct contact with sick animals via their contaminated respiratory droplets, nasal secretions and tissues. It can also be transmitted via consuming food contaminated with urine, droppings or saliva from infected bats, usually fruits or fruit products (particularly raw date palm sap). Human-to-human transmission is also possible through close contact with contaminated secretions and excretions of infected persons. Such transmission has been reported in patients' household and healthcare settings," the Controller of the CHP, Dr Edwin Tsui, said.

Patients infected with Nipah virus can be asymptomatic. 

Early symptoms include flu-like symptoms, such as fever, headache, vomiting, sore throat and muscle aches. Other symptoms include dizziness, drowsiness and a decrease in consciousness. Severe cases may develop complications such as pneumonia, seizure, encephalitis, coma or even death. The case fatality rate ranges from approximately 40 per cent to 75 per cent. Among the patients who survive acute encephalitis, around 20 per cent of them may have persistent nerve problems. Currently, there is no specific treatment or medication for Nipah virus infection. The mainstay of treatment is limited to supportive care. Symptoms usually start to develop around four to 14 days after exposure, but onset may occur as late as 45 days.

"Hong Kong has the ability to detect infections of unknown causes and emerging infectious diseases at boundary control points and in hospitals. On the immigration level, the DH conducts medical assessments for sick travellers at all boundary control points and refers them to hospitals for medical examinations as needed. The CHP has a robust communicable disease surveillance and notification mechanism that enables medical professionals to report suspected cases. So far, no cases of Nipah virus infection have been recorded. Although there are no direct flights between Kolkata and Hong Kong, the CHP will step up health screenings for passengers arriving from India at the airport as a precautionary measure. Port Health staff have been arranged to carry out temperature screenings for travellers at relevant flight gates, perform medical assessments on symptomatic travellers and refer suspected cases with potential public health implications to hospitals for examination," said Dr Tsui.

Dr Tsui reminded the public to take the following measures to reduce infection risk if travel to Nipah virus-affected areas is unavoidable:

-- Avoid contact with wild animals or sick farm animals, especially bats, farmed pigs, horses, domestic and feral cats.

-- Avoid areas where bats are known to roost.

-- Observe good personal hygiene; wash hands frequently with liquid soap and water, especially after contact with animals or their droppings/secretions, and after taking caring of or visiting sick people.

-- Observe food hygiene by thoroughly washing and peeling fruits before consumption. Fruits with signs of bat bites or found on the ground should not be consumed. Avoid drinking raw date palm sap, toddy or other juice.

 The CHP will monitor the situation and implement appropriate prevention and control measures based on risk assessments to safeguard public health and the well-being of citizens.

 

Ends/Monday, January 26, 2026

Issued at HKT 19:45

Source: 

Link: https://www.info.gov.hk/gia/general/202601/26/P2026012600674.htm?fontSize=1

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Integrating #Prevention and #Response at the Crossroads of #Henipavirus #Preparedness, Hendra@30 Conference, 2024

 

Abstract

Diseases caused by henipaviruses, exemplified by Hendra virus and Nipah virus, pose a serious risk to public health because of their epidemic potential and high case-fatality rates and the paucity of medical countermeasures to mitigate them. In December 2024, a group of 150 scientists from 16 countries convened in Geelong, Victoria, Australia, to mark the 30th anniversary of the discovery of Hendra virus. The Hendra@30 conference built upon its predecessor conference held in 2019 in Singapore, Nipah@20, by expanding its program across broader disciplines and integrating sessions on human sociology and disease ecology into the main scientific discussions. We describe key highlights from Hendra@30 and reflect on 4 key elements that have advanced henipavirus research and medical countermeasures research and development. We propose that integrating bat ecology into henipavirus research blueprints will enable development of ecologic countermeasures that prevent spillover and will complement existing preparedness and response efforts with evidence-based prevention strategies.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/32/1/25-0979_article

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#mRNA-lipid nanoparticle #vaccines provide protection against lethal #Nipah virus #infection

 

Abstract

Nipah virus (NiV) is a zoonotic pathogen that causes severe encephalitis and respiratory disease in humans and multiple mammalian species. However, no licensed vaccines or therapeutics are currently available against NiV infection. In this study, we developed three mRNA vaccine candidates using a lipid nanoparticle (LNP) delivery platform: mRNA-F-LNP, comprising mRNA encoding the fusion protein (F); mRNA-G-LNP, containing mRNA encoding the attachment glycoprotein (G); and mRNA-GF-LNP, in which mRNAs encoding both F and G proteins were co-encapsulated at a 1:1 molar ratio. All three mRNA-LNPs induced robust and sustained immune responses in both mice and Syrian hamsters. Sera from immunized Syrian hamster showed high levels of cross-neutralizing antibodies against both NiV-Malaysia (NiV-M) and NiV-Bangladesh (NiV-B) strains. Notably, all three mRNA-LNPs conferred complete protection against a lethal challenge with NiV-M in Syrian hamsters. These findings demonstrate that these mRNA-based vaccines are highly immunogenic and efficacious, highlighting their potential as promising candidates for NiV vaccine development.

Source: 

Link: https://www.nature.com/articles/s41541-025-01336-1

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Safety and immunogenicity of a #Nipah virus #vaccine (HeV-sG-V) in adults: a single-centre, randomised, observer-blind, placebo-controlled, phase 1 study

 

Summary

Background

First discovered in 1999 in Malaysia, Nipah virus (NiV) causes yearly outbreaks throughout south and southeast Asia with associated mortality rates of 40–75%. Due to the structural and sequence similarities between the NiV and Hendra virus (HeV) attachment G glycoproteins, and the extensive extant evidence of the ability of a recombinant soluble glycoprotein G (HeV-sG) to provide heterologous cross-protective immunity when used as vaccine (HeV-sG-V), this study aimed to evaluate HeV-sG-V for safety, tolerability, and immunogenicity against NiV.

Methods

We conducted a phase 1, single-centre, randomised, observer-blind, placebo-controlled study. Eligible participants were aged 18–49 years, healthy, and not pregnant; participants were ineligible if they were immunocompromised, had received blood products within 6 months of enrolment, had potential exposure to NiV or HeV, or had known allergies to components of the vaccine. Participants were randomly assigned in a 5:1 ratio to receive either one or two doses of the vaccine candidate (at 10 μg for the first cohort; 30 μg at days 1 and either days 8 or 29 for cohort 2; and 100 μg with the same timing for cohort 3) or placebo. The primary endpoints were solicited and unsolicited adverse events, clinically significant laboratory test result abnormalities, medically attended adverse events, and serious adverse events. Secondary endpoints were serum IgG binding via ELISA and neutralising antibody responses against prototypical NiV Bangladesh (NiVB) and NiV Malaysia (NiVM) reporter viruses.

Findings

Between Feb 24, 2020, and Oct 6, 2021, 268 participants were screened, and 192 were enrolled. 173 (90%) participants met the per-protocol criteria. Mild-to-moderate injection site pain was the most commonly reported adverse event. No serious adverse events, hospitalisations, or deaths were reported. The immune response to HeV-sG-V was dose-dependent; a single administration was not sufficiently immunogenic, whereas two administrations were immunogenic, with the highest response rates observed among vaccinees that received two administrations of the 100 μg HeV-sG-V 28 days apart (neutralising antibody geometric mean titres rose dramatically 7 days after the second investigational product dose, reaching 1485·6 (990·5–2228·1) and 2581·9 (147·1–3194·2) for NiVB and NiVM, respectively).

Interpretation

All three doses and regimens of HeV-sG-V had a tolerable risk profile and were able to induce an immune response. The induction of antibodies within 1 month of vaccination, along with the persistence afforded by two dosages, suggests the vaccine candidate has potential for reactive outbreak control and preventive use.

Funding

Coalition for Epidemic Preparedness Innovations (CEPI).

Source: 

Link: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)01390-X/abstract?rss=yes

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Safety and immunogenicity of a #Nipah virus #vaccine (HeV-sG-V) in adults: a single-centre, randomised, observer-blind, placebo-controlled, phase 1 study

 

Summary

Background

First discovered in 1999 in Malaysia, Nipah virus (NiV) causes yearly outbreaks throughout south and southeast Asia with associated mortality rates of 40–75%. Due to the structural and sequence similarities between the NiV and Hendra virus (HeV) attachment G glycoproteins, and the extensive extant evidence of the ability of a recombinant soluble glycoprotein G (HeV-sG) to provide heterologous cross-protective immunity when used as vaccine (HeV-sG-V), this study aimed to evaluate HeV-sG-V for safety, tolerability, and immunogenicity against NiV.

Methods

We conducted a phase 1, single-centre, randomised, observer-blind, placebo-controlled study. Eligible participants were aged 18–49 years, healthy, and not pregnant; participants were ineligible if they were immunocompromised, had received blood products within 6 months of enrolment, had potential exposure to NiV or HeV, or had known allergies to components of the vaccine. Participants were randomly assigned in a 5:1 ratio to receive either one or two doses of the vaccine candidate (at 10 μg for the first cohort; 30 μg at days 1 and either days 8 or 29 for cohort 2; and 100 μg with the same timing for cohort 3) or placebo. The primary endpoints were solicited and unsolicited adverse events, clinically significant laboratory test result abnormalities, medically attended adverse events, and serious adverse events. Secondary endpoints were serum IgG binding via ELISA and neutralising antibody responses against prototypical NiV Bangladesh (NiVB) and NiV Malaysia (NiVM) reporter viruses.

Findings

Between Feb 24, 2020, and Oct 6, 2021, 268 participants were screened, and 192 were enrolled. 173 (90%) participants met the per-protocol criteria. Mild-to-moderate injection site pain was the most commonly reported adverse event. No serious adverse events, hospitalisations, or deaths were reported. The immune response to HeV-sG-V was dose-dependent; a single administration was not sufficiently immunogenic, whereas two administrations were immunogenic, with the highest response rates observed among vaccinees that received two administrations of the 100 μg HeV-sG-V 28 days apart (neutralising antibody geometric mean titres rose dramatically 7 days after the second investigational product dose, reaching 1485·6 (990·5–2228·1) and 2581·9 (147·1–3194·2) for NiVB and NiVM, respectively).

Interpretation

All three doses and regimens of HeV-sG-V had a tolerable risk profile and were able to induce an immune response. The induction of antibodies within 1 month of vaccination, along with the persistence afforded by two dosages, suggests the vaccine candidate has potential for reactive outbreak control and preventive use.

Funding

Coalition for Epidemic Preparedness Innovations (CEPI).

Source: The Lancet, https://www.sciencedirect.com/science/article/abs/pii/S014067362501390X?dgcid=rss_sd_all

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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.

__

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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