ETIDIOH - NEW

  Abstract We describe the clinical symptoms and epidemiologic characteristics of a patient infected with avian influenza A(H10N3) virus in Guangxi Province , China , in December 2024. Whole-genome sequencing showed that the virus was highly homologous to a virus from Yunnan Province . H10 subtype viruses should be monitored for potential zoonotic or reassortant events. {From Emerging Infectious Diseases Journal, US CDC.} Sources:  Link:  https://pubmed.ncbi.nlm.nih.gov/41237415/ ____

  Abstract Highly pathogenic avian influenza H5N1 rarely infects mammals. In 2024-2025, however, genotypes B3.13 and D1.1 caused two independent spillovers into U.S. dairy cattle . By analysing 26,930 complete H5N1 genomes from global surveillance , we identified 73 major viral groups , most of which show continent-specific distribution in Europe, Asia, Africa , and North America . North American viruses exhibit higher genetic diversity in specific viral segments , including variants potentially associated with mammalian adaptation . Both dairy-cattle-associated B3.13 and D1.1 genotypes originate from the same geographic macro-area , suggesting a possible regional hotspot where avian-mammalian interfaces may facilitate viral adaptation. Our findings place the U.S. outbreaks in a global framework and indicate that North American H5N1 may be predisposed to cross-species transmission. Competing Interest Statement The authors have declared no competing interest. Funder Information Decl...

  Abstract The unprecedented 2.3.4.4b. A(H5N1) outbreak in dairy cattle, poultry, and spillover to humans in the United States (US) poses a major public health threat. Population immunity is a critical component of influenza pandemic risk assessment . We assessed the pre-existing cross-reactive immunity to 2.3.4.4b A(H5N1) viruses and analyzed 1794 sera from 723 people (0.5–88 yrs) in multiple US geographic regions during 2021–2024. Pre-existing neutralizing and hemagglutinin (HA)-head- binding antibodies to A(H5N1) were low , but there were substantial cross-reactive binding antibodies to N1 neuraminidase (NA) of 2.3.4.4b A(H5N1). Antibodies to group 1 HA stalk were also prevalent and increased with age . A(H1N1)pdm09 infection and influenza vaccination did not induce neutralizing antibodies to A(H5N1) viruses but induced significant rise of functional NA inhibition (NAI) antibodies to N1 of 2.3.4.4b A(H5N1), and group 1 HA stalk antibodies . Moreover, pre-pandemic stockpiled 2.3....

{Excerpt} Country 2024 (cases - deaths) - 2025 (cases - deaths) - Total (cases - deaths) 1) Australia - 1 - 0 - 0 - 0 - 1 - 0   2) Azerbaijan - ... - ... - 0 - 0 - 8 - 5  3) Bangladesh - ... - ... -  3 - 0 - 11 - 1  4) Cambodia - 10 - 2 - 17 - 8 - 89 - 51  5) Canada - 1 - 0 - 0 - 0 - 2 - 1  6) Chile - ... - ... - 0 - 0 - 1 - 0  7) China - 1 - 0 - 1 - 0 - 57 - 32  8) Djibouti - ... - ... - 0 - 0 - 1 - 0  9) Ecuador - ... - ... - 0 - 0 - 1 - 0  10) Egypt - ... - ... - 0 - 0 - 359 - 120  11) India - ... - ... - 2 - 2 - 3 - 3  12) Indonesia - ... - ... - 0 - 0 - 200 - 168  13) Iraq - ... - ... - 0 - 0 - 3 - 2  14) Lao People's Democratic Republic - ... - ... - 0 - 0 - 3 - 2  15) Mexico - ... - ... - 1 - 1 - 1 - 1  16) Myanmar - ... - ... - 0 - 0 - 1 - 0  17) Nepal - ... - ... - 0 - 0 - 1 - 1  18) Nigeria - ... - ... - 0 - 0 - 1 - 1  19) Pakistan - ... - ... - 0 - 0 - 3 - 1  20) Spain - ... - ...

  Abstract Avian influenza viruses (AIVs) pose a significant zoonotic threat, with the emerging H3N8 subtype raising increasing concern due to sporadic human infections . Current strategies for risk assessment of novel AIVs primarily rely on genetic surveillance and isolated case reports, which provide limited insight into their cross-species transmission potential . However, these approaches may overlook critical phenotypic determinants , such as pathogenicity, transmissibility, and environmental persistence , that directly influence zoonotic risk . This study investigates the evolutionary relationships , receptor-binding properties, replication dynamics, pathogenicity in mice, transmission efficiency in guinea pigs, and environmental persistence of three H3N8 strains isolated from a live poultry market . All three H3N8 strains bound exclusively to α-2,3 sialic acid receptor and achieved 100% transmissibility among guinea pigs through direct contact . Notably, the environment-orig...

  Abstract Finland faced an outbreak of highly pathogenic clade 2.3.4.4b A(H5N1) avian influenza in 2023, which spread from wild birds to fur farms . Vaccinations of at-risk individuals began in June 2024 using the MF59-adjuvanted inactivated A(H5N8) vaccine (Seqirus; A/Astrakhan/3212/2020, clade 2.3.4.4b). Here, in an observational study , we assessed vaccine-induced immune responses in occupational at-risk individuals participating in the phase IV trial , including virus-specific antibody (n = 39 individuals) and T-cell (n = 18 individuals) responses. Vaccination elicited functional antibodies against the vaccine virus and two heterologous clade 2.3.4.4b strains associated with outbreaks on Finnish fur farms and dairy cattle in the United States . Among previously unvaccinated individuals, seroprotection rates against the vaccine virus were 83% (95% CI 70–97%) by microneutralization assay (titre ≥20) and 97% (90–100%) by haemagglutination inhibition assay (titre ≥40). In those pr...

  5 December 2025 Situation at a glance On 15 November 2025, WHO was notified of the 71st confirmed human case with influenza A(H5) since early 2024 in the United States of America — the first human case reported in the United States of America since February 2025 .  On 20 November, U.S. Centers for Disease Control and Prevention (CDC) laboratory sequencing verified the virus as influenza A(H5N5), representing the first globally reported human case caused by an influenza A(H5N5) virus.  The investigation by health authorities in the United States of America is ongoing.  Contact tracing identified no further cases amongst contacts, and there is currently no evidence of human-to-human transmission .  Due to the constantly evolving nature of influenza viruses , WHO continues to stress the importance of global surveillance to detect and monitor virological (including genomics), epidemiological and clinical changes associated with emerging or circulating influenza vi...

  Abstract The wildlife reservoir and spillover mechanisms of Ebola virus remain elusive despite extensive research efforts in endemic areas. This study employed a One Health approach to examine the virus’ circulation in wildlife and the associated human exposure risks in the Tshuapa province of the Democratic Republic of the Congo . We screened 1049 samples from 919 animals , predominantly small mammals , collected in 2021, and 380 samples from inhabitants of Inkanamongo village, the site of an Ebola virus disease outbreak in 2014. These samples were screened for evidence of current (RNA) or past (IgG antibodies) Ebola virus infections. We also conducted interviews with 167 individuals in the surrounding districts to assess their interactions with wildlife . While no Ebola virus RNA was detected in the wildlife samples , anti-orthoebolavirus IgG antibodies were found in 13 bats and 38 rodents . Among the human participants , 120 individuals had IgG antibodies against at least 1 or...

  Abstract Background   Infection of backyard and poultry with low pathogenicity avian influenza LPAI A(H5N2) viruses has occurred in Mexico since 1994, and the first human infection caused by this influenza virus was detected in 2024 . Since its emergence in the Americas , frequent reassortments between high pathogenicity avian influenza HPAI A(H5N1) and LPAI viruses has occurred. In September 2025 , the Instituto Nacional de Enfermedades Respiratorias of Mexico City identified an unsubtypeable influenza A virus infection in a young adult patient later determined to be a reassortant HPAI (H5N2) virus with a clade 2.3.4.4b HA .  Methods   We analyzed clinical and epidemiologic data from this patient. Respiratory samples were tested for influenza RT-qPCR assays . Genomic sequence and phylogenetics analyses were performed to provisionally assign a new genotype to the novel HPAI A(H5N2) reassortant virus.  Results   The patient presented with fever and tachypn...

  {Summary} Confirmed Cases at National Level [National - Total Cases : 71 { +1 }{§}] [Cases -  Exposure Source] -- 41 - Dairy Herds (Cattle){*} -- 24 - Poultry Farms and Culling Operations {*} -- 3 - Other Animal Exposure {†} -- 3 - Exposure Source Unknown {‡} Probable Cases at National Level [National - Total Cases : 7 {no change} ] [Cases -  Exposure Source] -- 1 - Dairy Herds (Cattle) {*} -- 5 - Poultry Farms and Culling Operations {*} --  0 - Other Animal Exposure {†} -- 1 - Exposure Source Unknown {‡} NOTE : One additional case was previously detected in a poultry worker in Colorado in 2022. Louisiana reported the first H5 bird flu death in the U.S. {*} Exposure Associated with Commercial Agriculture and Related Operations {†} Exposure was related to other animals such as backyard flocks, wild birds, or other mammals {‡} Exposure source was not able to be identified (...) {§} A case from Washington State, see more at:  https://doh.wa.gov/newsroom/grays-h...

  Abstract Three critically ill or fatal avian influenza A(H5N1) human infections have been reported in North America since November 2024 . Notably, all were infected with genotype D1.1 instead of B3.13, the dominant genotype before November 2024. Here, we demonstrated that D1.1 could replicate to higher titers in human nasal and airway organoid-derived transwell monolayers from 6 donors . D1.1 exhibited a better binding to α2,3- and α2,6-linked SA than B3.13. No significant differences in most inflammatory or antiviral cytokines/chemokines was observed. These observations suggest that D1.1 is better adapted to both the upper and lower human respiratory tract epithelium than B3.13. Source:  Link:  https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiaf598/8341570#google_vignette ____

  The person was infected with the H5N5 virus; the risk to the public remains low OLYMPIA – A Grays Harbor County resident who was undergoing treatment for H5N5 avian influenza died today .  The Washington State Department of Health offers its heartfelt condolences to the person’s family and friends. The person was an older adult with underlying health conditions .  Out of respect for the family’s privacy , we are not releasing their name, gender, or age.  The person had been hospitalized in King County since early November. Testing at the UW Medicine Clinical Virology Lab identified the virus as H5N5 , making this the first recorded infection with this variant in a person globally.  The result was confirmed by the Centers for Disease Control and Prevention (CDC). The risk to the public remains low .  No other people involved have tested positive for avian influenza.  Public health officials will continue to monitor anyone who was in close contact with...

  {Excerpt} Novel Influenza A Virus Infections Two confirmed human infections with novel influenza A viruses were reported to CDC this week .  One infection with an influenza A(H5N5) virus was reported by the Washington State Department of Health and one infection with an influenza A(H1N2) variant (A(H1N2)v) virus was reported by the Vermont Department of Health. One infection with an influenza A(H5N5) virus was reported by the Washington State Department of Public Health .  -- The case occurred in an individual aged ≥18 years .  -- This individual developed symptoms during the week ending October 25 , 2025 (Week 43) and was hospitalized with their illness during the week ending November 8, 2025 (Week 45).  -- Respiratory specimens collected at the healthcare facility tested positive for influenza A and were presumptive positive for influenza A(H5) at the University of Washington.  -- The specimens were sent to the Washington State Public Health Laboratory ...

  Abstract The Middle East respiratory syndrome coronavirus (MERS-CoV) remains a highly significant threat to global public health . Dromedary camels are the zoonotic source of human infection. All cases of zoonotic Middle East respiratory syndrome (MERS) have occurred in Middle Eastern countries despite MERS-CoV infection of camels being widespread in Africa . This disparity in the geographic burden of the disease may be due to genomic differences between MERS-CoV circulating in Middle Eastern countries (clades A and B) versus those infecting camels in Africa ( clade C ), although the precise genetic determinants of virulence remain to be elucidated. The objective of the studies reported here was to evaluate differences in the magnitude of virus shedding and in transmissibility of clades A/B and C viruses using alpacas as a surrogate for dromedary camels. We found that two of three African-origin, clade C strains of MERS-CoV induced very reduced levels of virus shedding and were t...

  • New human cases {1,2}:  -- From 30 September to 5 November 2025 , based on reporting date, the detection of influenza A(H5N1) in one human , A( H5N2 ) in one human and A( H9N2 ) in two humans were reported officially.   • Circulation of influenza viruses with zoonotic potential in animals :  -- High pathogenicity avian influenza (HPAI) events in poultry and non-poultry animal species continue to be reported to the World Organisation for Animal Health (WOAH).{3}  -- The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}  • Risk assessment {5}:  -- Sustained human to human transmission has not been reported in the above human infection events.  -- Based on information available at the time of this risk assessment update , the overall public health risk from currently known influenza A viruses detected at the human-animal interface has not changed...