Influenza at the human-animal interface
Summary and risk assessment, from 8 August to 6 September 2026 {1}
• New human cases {2}:
° From 8 August to 6 September 2026, based on reporting date, detections of influenza A(H5N1) in one human and influenza A(H9N2) in three humans were officially reported. Additionally, two human cases of infection with influenza A(H1N2) variant (A(H1N2)v) viruses were detected.
• 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} Additionally, low pathogenicity avian influenza viruses as well as swine influenza viruses continue to circulate in animal populations.
• Risk assessment {5}:
° There have been no reports of sustained human-to-human transmission associated with the above-mentioned human infection events. Based on information available at the time of this update, the overall public health risk from currently known influenza A viruses detected at the human-animal interface has not changed and, at present, these viruses are not thought to be capable of sustained human-to-human transmission, although this could change as they evolve. Whilst human infections with viruses of animal origin are infrequent, they are not unexpected at the human-animal interface.
• IHR compliance {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
A(H5N1), Bangladesh
On 30 August, Bangladesh, through the national IHR focal point, notified WHO of one laboratory-confirmed human infection with an A(H5) virus in a child from Rangpur division.
On 15 August 2026, the child developed a fever, cough and rhinitis and was admitted to hospital on 17 August.
On 18 August, a nasopharyngeal swab and throat swab was collected as part of hospital-based influenza surveillance and tested positive for influenza A(H5) by real-time RT-PCR at the icddr,b laboratory on the same day.
The sample was subsequently confirmed positive for influenza A(H5N1) at the Molecular and Genomic Laboratory Department of Institute of Epidemiology, Disease Control and Research (IEDCR) and National Influenza Centre (NIC) of Bangladesh.
Genetic sequencing is underway.
The child remained hospitalized and was improving clinically at the time of reporting.
There was no reported history of travel outside the area of residence. The child had a history of exposure to duck and chickens, including some that were sick, in the household and adjacent households.
Poultry meat and oropharyngeal swab specimens collected from several backyard chickens on 26 August tested negative for influenza A(H5).
Close contacts were identified and placed under monitoring and all contacts remained asymptomatic during the observation period, except for two heath care workers.
Respiratory specimens collected from these two individuals tested negative for influenza A viruses.
This is the 4th laboratory-confirmed human case of avian influenza A(H5) reported in Bangladesh in 2026.
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, Europe and Oceania. 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(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 infections so far have been reported in people exposed to A(H5N1) 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 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-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(H5N1) 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.
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
Between 13 August and 1 September 2026, China notified WHO of three laboratory-confirmed human cases of A(H9N2) virus infection.
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All cases had direct or indirect exposure to poultry and/or local live bird markets. Samples from environments associated with the likely area of exposure of some of the cases tested positive for A(H9) viruses.
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, additional human cases associated with exposure to infected poultry or contaminated environments are expected but remain unusual. The impact to public health if additional sporadic cases are detected is minimal. The overall global public health risk is low.
2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H9N2) viruses related to these events?
° At the present time, no sustained human-to-human transmission has been identified associated with the recently reported human infections with A(H9N2) viruses. Current evidence suggests that A(H9N2) viruses from these cases did not acquire the ability of sustained transmission among humans.
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(H1N2)v, United States of America
Since the risk assessment of 8 August 2026, two human infections with influenza A(H1N2v) viruses were detected in the state of Michigan.{7}
The patients, both <18 years of age, developed illness in the week of 15 August. They were not hospitalized and have recovered. Both attended the same agricultural fair where sick swine were present. The cases did not have contact with each other and no additional human infections with A(H1N2)v viruses have been detected around this event.
Including these two cases, there have been a total of three human infections with variant influenza A viruses reported in the United States in 2026.
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 for public health if additional cases are detected is minimal. The overall risk of additional 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 suggest that these viruses have not acquired the ability to transmit easily among humans.
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.
• 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.{8} 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 must be maintained at all times, including during a non-influenza emergency. To maximize the value of influenza surveillance platform for other respiratory threats, 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).{9,10} 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. 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 risk elements. The results of TIPRA complement those of the risk assessment provided here, and those of prior TIPRA risk assessments are published at http://www.who.int/teams/global-influenza-programme/avianinfluenza/tool-for-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/
° WOAH/FAO Network of Expertise on Animal Influenza (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} Avian influenza. Global situation. World Organisation for Animal Health (WOAH) (https://www.woah.org/en/disease/avian-influenza/#ui-id-2).
{4} Global Avian Influenza Viruses with Zoonotic Potential situation update. Food and Agriculture Organization of the United Nations (FAO) (https://www.fao.org/animal-health/situation-updates/global-aiv-with-zoonoticpotential).
{5} Rapid risk assessment of acute public health events. World Health Organization; 2012 (https://iris.who.int/handle/10665/70810).
{6} Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005). World Health Organization; 2009 (https://www.who.int/publications/m/item/casedefinitions-for-the-four-diseases-requiring-notification-to-who-in-all-circumstances-under-the-ihr-(2005)).
{7} Weekly US Influenza Surveillance Report: Key Updates for Week 32, ending August 15, 2026. US Centers for Disease Control and Prevention; 2026 (https://www.cdc.gov/fluview/surveillance/2026-week-32.html).
{8} World Organisation for Animal Health. Statement on High Pathogenicity Avian Influenza in Cattle, 6 December 2024 (https://www.woah.org/en/high-pathogenicity-avian-influenza-hpai-in-cattle/).
{9} World Health Organization. International Health Regulations (2005), as amended through resolutions WHA67.13 (2014), WHA75.12 (2022), and WHA77.17 (2024) (https://apps.who.int/gb/bd/pdf_files/IHR_2014-2022-2024-en.pdf).
{10} World Health Organization. Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005) (https://www.who.int/publications/m/item/casedefinitions-for-the-four-diseases-requiring-notification-to-who-in-all-circumstances-under-the-ihr-(2005)).
{11} World Health Organization. Manual for the laboratory diagnosis and virological surveillance of influenza (2011) (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 (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) (https://apps.who.int/iris/handle/10665/259402).
Source:
Link: https://www.who.int/publications/m/item/influenza-at-the-human-animal-interface-summary-and-assessment--6-september-2026
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