2025年9月29日，人-动物界面流感总结与评估

1 •Newhumancases12:From26 August to 29 September2025,based on reporting date,thedetection ofinfluenza A(H5) in one human,influenzaA(H5N1) inonehuman,influenza A(H9N2)ineighthumansandaninfluenza A(H1N1) variant((H1N1)v)virusin one humanwerereportedofficially.•Circulation ofinfluenza viruseswith zoonotic potentialin animals:High pathogenicity avianinfluenza (HPAI) eventsinpoultry and non-poultryanimal speciescontinue to be reported to theWorld Organisation for Animal Health (WOAH).3The Food and Agriculture Organization of theUnited Nations (FAO) alsoprovides a global update on avian influenza viruses with pandemicpotential.4•Risk assessment5:Sustained human to human transmission has not been reported from theseevents.Based on information available at the time of thisrisk assessmentupdate,the overallpublic health risk from currently knowninfluenzaAvirusesdetectedat the human-animalinterface has not changedandremains low.The occurrence of sustained human-to-humantransmission of these viruses is currently considered unlikely.Althoughhuman infections withviruses of animal origin areinfrequent, theyarenot unexpectedat the human-animal interface.•Risk management:Candidate vaccine viruses (CVVs) for zoonotic influenza viruses for pandemicpreparedness purposes werereviewed and updatedat theSeptember2025 WHO consultationon influenza vaccine composition for use in thesouthern hemisphere2026 influenza season. Adetailed summary of zoonotic influenza viruses characterized sinceFebruary2025is publishedhereand updated CVVs lists are publishedhere.•IHR compliance:All human infections caused by a new influenza subtype are required to bereported under the International Health Regulations (IHR).6This includesany influenza A virusthat has demonstrated the capacity to infect a human and its haemagglutinin(HA)gene (orprotein) is nota mutated form of those, i.e. A(H1)or A(H3), circulating widely in the humanpopulation. Information from these notificationsis criticalto inform risk assessments forinfluenza at the human-animal interface. Avianinfluenzavirusesin humansCurrent situation: Since the last risk assessment of25 August2025,onelaboratory-confirmed human case ofA(H5)infectionwasdetected inBangladesh,andone laboratory-confirmed human case of A(H5N1) virusinfection wasdetected inCambodia. A(H5), BangladeshOn 19 August 2025, Bangladesh notified WHO of one laboratory-confirmed human infection with avian influenza A(H5) virus inaboy in Sylhet Division. The case developed fever and cough on 27 Julyand was admitted to hospital on1 August.Oropharyngeal and nasopharyngeal swabs collected on 4August and tested at the Virology Laboratory of the International Centre for Diarrhoeal DiseaseResearch, Bangladesh (icddr,b) and the Institute of Epidemiology, Disease Control & Research(IEDCR) tested positive for influenza A(H5) virus byreverse transcription-polymerase chain reaction(RT-PCR).on 14 August. Subtyping for the N-typewaspendingat the time of notification. The casewas detected through the Hospital-Based Influenza Surveillance (HBIS) platform.The casewasdischarged on 7 August. A seven-member multidisciplinary team, comprising physicians, epidemiologists, an anthropologist,and a technologist, was deployed on 15 August to conduct an investigation. The child had no historyof travel and no reported exposure to backyard poultry, however the familypurchased chickensfrom a local market in the days preceding thechild’sillness.All samplescollected from contactstested negativefor influenza A(H5) virus.Samples collectedpoultry attwo markets that werefrequently visited by the family of the casetested positive forinfluenza A(H5)virus. This is the 12th human case of avian influenza A(H5) reported to WHO from Bangladesh and thefourth in 2025.Where the genetic sequence data is available, theviruses from the human casesthusfarare identified as clade 2.3.2.1aviruses. A(H5N1), CambodiaOn 9 September 2025, Cambodia notified WHO of alaboratory-confirmed human infection with avian influenza A(H5N1) in agirlfrom Takeo Province. The case, with no known underlying medicalconditions,had an onset of fever, cough and dyspnea on 1 Septemberandwas admitted tohospitalon 5 September.Nasopharyngeal and oropharyngeal swabs collectedon 7 September testedpositive for avian influenza A(H5N1)at the National Institute of Public Health (NIPH)RT-PCR.Laboratory results were confirmed by the Institut Pasteur du Cambodge, National Influenza Center(NIC) on 8 September.Treatment with oseltamivir was initiatedon 7 September. As part of the response, active case finding identified 10 close contacts and two villagers presentingwith influenza-like illness (ILI). Allnasopharyngeal and oropharyngeal samples collected from closecontacts,symptomatic villagers and health workerstested negative forinfluenza A(H5N1) virus.Aweek before symptom onset, approximately 10 to 20 sick or dead chickens were observed at the case’sresidence and at a neighbouring house. The case prepared and coo