#Italy - #Influenza A #H5 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 

{Eurasian Teal}

{Eurasian Wigeon}

{Mute Swan}

___

This is a new event opened to report outbreaks for which the N subtype could not be determined due to insufficient diagnostic material; in these cases, only the presence of H5 can be confirmed.

Three Common Teals (Friuli Venezia Giulia, Lombardy) , two Eurasian Wigeons (Friuli Venezia Giulia), one Mute Swan (Lombardy). 

Source: 

Link: https://wahis.woah.org/#/in-review/7144

____

#Brazil - #Influenza A #H5N1 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 

The Official Veterinary Service (OVS) of the state of Mato Grosso received a notification of a suspected case influenza A viruses of high pathogenicity in domestic birds from a multi-species backyard, on December 20, 2025. Official Laboratory (LFDA-SP) analysis confirmed the presence of the H5N1 virus, clade 2.3.4.4b. The premises have been placed under quarantine. Birds will be culled, and carcasses, products, and any potentially contaminated materials will be destroyed. The OVS is currently conducting an epidemiological investigation in the surrounding area.

Source: 

Link: https://wahis.woah.org/#/in-review/7147

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Emergence of D1.1 #reassortant #H5N1 avian #influenza viruses in North #America

 

Abstract

Since 2021, highly pathogenic avian influenza viruses (HPAIV) belonging to H5N1 clade 2.3.4.4b have caused high mortality in North American wild birds and poultry. In 2025, a new D1.1 genotype caused two human deaths and host-switched to dairy cattle. However, the evolutionary origins and dynamics of D1.1 have not been fully characterized. Here, our phylogenetic analysis of 17,516 H5N1 genome sequences uncovers how D1.1 introduced a major shift in the antigenic diversity and ecology of the H5N1 epizootic in North America. D1.1 is the first major H5N1 genotype to (a) emerge in the Pacific flyway and spread west-to-east faster than any prior genotype; (b) antigenically shift via reassortment with the North American N1 segment, displacing the previously fixed Eurasian N1; and (c) transmit to a broader range of host species than any H5N1 genotype to date, introducing mammalian adaptations.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Research Foundation - Flanders, https://ror.org/03qtxy027, G098321N, G0E1420N

European Union Horizon 2023 RIA project LEAPS, 101094685

DURABLE EU4Health project 02/2023-01/2027, 101102733

Fonds National de la Recherche Scientifique, F.4515.22

European Union Horizon 2020 project MOOD, 874850

Source: 

Link: https://www.biorxiv.org/content/10.64898/2025.12.19.695329v1

____

Enhanced #genome #replication activity of pandemic #H1N1 #influenza A virus through PA #mutations

 

ABSTRACT

The 2009 pandemic H1N1 (pH1N1) influenza A virus (IAV) is a reassortant virus with two polymerase components, PA and PB2, originating from avian IAV. Avian IAV polymerase does not function efficiently in mammalian cells without host-adaptive mutations. The mechanism by which pH1N1 replicates in human hosts is not fully elucidated, as pH1N1 does not contain the host-adaptive PB2 E627K mutation required for species-specific interaction with ANP32, which facilitates replicase (polymerase oligomer) formation. Our previous research revealed that mutations in PA played a key role in mammalian host adaptation of pH1N1. These mutations were found in two separate domains of PA, the C-terminal (CTD) and N-terminal domains (NTD). We reported that the NTD mutations increase the expression of NP through enhanced association of GRSF1 with the mRNA transcripts. However, the role of CTD mutations, which are located at the interface of the polymerase oligomers, has not been elucidated. In this study, we characterized the effect of key CTD mutations and found that the CTD mutations enhanced genome replication activity and replicase formation in vitro. Unexpectedly, rescued viruses containing only the CTD mutations that enhance genome replication activity had an attenuated viral growth phenotype. However, the introduction of an additional NTD mutation to the virus restored virus growth in mammalian cells. These results suggest that the mutations found in the PA NTD are required together with CTD mutations for balanced genome replication and growth in human cells.

Source: 

Link: https://journals.asm.org/doi/full/10.1128/jvi.01391-25?af=R

____

#Influenza D Virus in Black #Donkeys, Northern #China

 

Abstract

Influenza D virus (IDV) is prevalent in cattle in China, and a risk for spillover to other species exists. We detected IDV antibodies in 6/315 of black donkeys in northern China, suggesting cattle-to-donkey transmission and demonstrating the expanding host range of IDV and the need for reassessment of cross-species transmission risks.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/31/12/25-0666_article

____

Highly Pathogenic Avian #Influenza #H5N1 Clade 2.3.4.4b Virus #Infection in Poultry Farm #Workers, #Washington, #USA, 2024

 

Abstract

Poultry workers in Washington, USA, were infected with highly pathogenic avian influenza A(H5N1) virus and recovered. The viruses were clade 2.3.4.4b genotype D1.1, closely related to viruses causing poultry outbreaks. Continued surveillance and testing for influenza A(H5) clade 2.3.4.4b viruses remain essential for risk assessment and pandemic preparedness of zoonotic influenza viruses.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/31/12/25-1118_article

____

#China, three additional #human cases of #infection with #H9N2 avian #influenza virus (HK CHP, Dec. 23 '25)

{Excerpt} 

Avian influenza A(H9N2): 

-- Guangdong Province: 

1) An individual with onset in November 2025. 

-- Guangxi Zhuang Autonomous Region: 

2) An individual with onset in November 2025. 

-- Hubei Province: 

3) An individual with onset in November 2025. 

(...)

Source: 

Link: https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk51.pdf

____

#Zoonotic and #Avian #Pathogen Detections in Fecal and Sediment #Samples - A Low-risk, High-throughput One Health Approach to #Surveillance

 

Abstract

Many pathogens, both those with human spillover potential as well as avian-specific viruses, are maintained in wild bird populations. While much surveillance for influenza A viruses (IAVs) is performed annually, surveillance for other pathogens is limited. Sampling of wild birds is often time-consuming, labour-intensive, involves physically handling wild birds, often limited in sample size, and involves handling of potentially infected birds, posing an increased risk of direct exposure for personnel. Given this, additional methods for surveillance are needed. Longitudinal, bi-weekly fecal and sediment sampling was performed at various sites in southern Manitoba, Canada, particularly focused in Winnipeg from May - October 2025. Sites were chosen based on the suitability of the area for waterfowl habitat, the presence of waterfowl in the area, as well as sites in proximity to reported outbreaks of H5N1 influenza virus. Fecal and sediment samples were collected and screened for the presence of influenza A virus (IAV), Newcastle disease virus (NDV), avian reovirus (ARV), and avian poxvirus (APXV). In total, 782 combined fecal and sediment samples were collected. Of the 714 fecal samples, 34 tested positive for IAV (4.8% prevalence). None of the IAV-positive fecal samples tested positive for H5 RNA. Of the 68 sediments tested, 15 tested positive for IAV (22.1% prevalence), four of which further tested positive for H5 RNA. NDV positivity was low, with only four positive fecal samples (0.56% prevalence) that were all collected on the same day. ARV positivity was also low, with five positive sediment samples (7.4% prevalence in sediment samples). Of the 782 total samples collected, of 559 samples that have been tested for APXV to date, all have tested negative. This work expands upon previous work showing the utility of environmental sampling for a variety of avian and zoonotic pathogens using a One Health approach that is both high-throughput and low-risk.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Canadian Institutes of Health Research, Tier 2 Canada Research Chair, 950 231498

Natural Sciences and Engineering Research Council, RGPIN-2018-06036

Source: 

Link: https://www.biorxiv.org/content/10.64898/2025.12.19.694637v1

____

The spatial and temporal #spread of highly pathogenic avian #influenza in North #America: Newton's Cradle hypothesis

 

Abstract

The recent emergence of highly pathogenic H5N1- especially clade 2.3.4.4b has led to widespread mortality in poultry and wild birds and has raised significant concerns for the dairy industry and human health. Migratory waterfowl are considered the main source of infection, and we used publicly available surveillance data and bird observation data from continental North America to show clear seasonal signals correlated with waterfowl movement, both on the continental scale and in three of the four flyways. In early 2024, the virus expanded its host range, and we observed a phase transition with the loss of the seasonal signal coupled with a concomitant increase in the proportion of mammalian cases. We also identified a second harmonic, with a regional east-to-west movement with infections spreading between regional flyways, followed by local viral amplification. We likened this to the movement of balls in a Newton's Cradle with an analogy between potential and viral energy. We used bird data to identify bird species associated with viral cases and identified specific waterfowl species and highlighted the importance of predatory and scavenging birds, specifically raptors and gulls, in local amplification. These findings will help to focus surveillance strategies both at local and regional levels.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

United States Department of Agriculture, AP23OA000000C025

Center for Poultry and Livestock Excellence, CPLE23-11

Source: 

Link: https://www.biorxiv.org/content/10.64898/2025.12.19.695483v1

____

Digest: #Reassortment-based #evolution of #H1N1 subtype Swine #Influenza Virus in #China

 

Abstract

In a new study, Zhao et al. (2025) obtain 959 whole genome sequences of H1N1 subtype swine influenza virus (SIV) isolated from China. Their analysis of the sequences, isolated between 1977 and 2020, reveals how H1N1 lineages have co-evolved and contributed to instances of zoonotic transmission within the region. This study’s findings characterize the long-term evolutionary effects of frequent viral reassortment in SIV and highlight its potential to drive future pandemics.

Source: 

Link: https://academic.oup.com/evolut/advance-article/doi/10.1093/evolut/qpaf262/8400336

____

#Mpox - Multi-country external #situation #report no. 61, published 22 December 2025 (#WHO, summary)

{Summary}

Highlights   

• All clades of monkeypox virus (MPXV) continue to circulate. 

- Unless mpox outbreaks are rapidly contained and human-to-human transmission is interrupted, there is a risk of sustained community transmission.  

• In November 2025, 48 countries across all WHO regions reported a total of 2150 new confirmed mpox cases, including five deaths (case fatality ratio [CFR] 0.2%). 

- About 68% of these cases were reported in the African Region. 

- Four regions observed a decline in confirmed cases in November, compared to October 2025, while the European and Western Pacific regions reported more cases than the previous month.     

• Nineteen countries in Africa reported active transmission of mpox in the last six weeks (2 November– 14 December 2025), with 1435 confirmed cases, including seven deaths (CFR 0.5%). 

- Countries reporting the highest number of cases in this period are the Democratic Republic of the Congo, Guinea, Liberia, Kenya and Ghana; while case reports in Liberia still show indications of a rise, weekly case counts in the other countries have been declining in recent weeks. 

• Romania has reported detection of clade Ib MPXV for the first time, in a case confirmed in August 2025.   

• Outside Africa, community transmission of clade Ib MPXV continues in Spain and in the Netherlands. 

• In the Democratic Republic of the Congo, mpox transmission continues across multiple provinces with cocirculation of clades Ia and Ib MPXV, heterogeneous subnational trends and declining access to testing of suspected cases. 

• The United Kingdom of Great Britain and Northern Ireland has reported a new travel-linked case of mpox with detection of a recombinant MPXV strain containing genetic elements of both clade Ib and clade IIb MPXV. The extent of circulation of the recombinant strain remains unknown.  

• WHO assesses the ongoing public health risk to be moderate for men who have sex with men with new or multiple partners, sex workers and others with multiple partners who may be at risk, and low for the general population with no specific risk factors, continues close monitoring of the situation, and emphases the importance of maintaining surveillance and response capacity, including genomic sequencing notably in locations where multiple MPXV strains co-circulate. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/multi-country-outbreak-of-mpox--external-situation-report--61---22-december-2025

____

#Influenza at the #human - #animal #interface - Summary and #risk #assessment, from 6 November to 19 December 2025 (#WHO, edited)

 

Influenza at the human-animal interface 

Summary and risk assessment, from 6 November to 19 December 2025 {1}

-- New human cases {1,2}: 

- From 6 November to 19 December 2025, based on reporting date, the detection of influenza A(H5N1) in one human, A(H5N5) in one human, A(H9N2) in seven humans, and an influenza A(H1N1) variant virus in one human were reported officially. 

- In addition, one human case of infection with an influenza A(H1N2) variant virus was 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}: 

- Sustained human to human transmission has not been reported associated with the above-mentioned 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 and remains low. 

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

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

-- 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 

-- Current situation:  

- Since the last risk assessment of 5 November 2025, one laboratory-confirmed human case of A(H5N1) infection was detected in Cambodia, and one laboratory-confirmed human case of A(H5N5) virus infection was detected in the United States of America. 

A(H5N1), Cambodia 

- On 16 November 2025, Cambodia notified WHO of a confirmed human infection with avian influenza A(H5N1) in a 22-year-old male from Phnom Penh. 

- The case developed symptoms on 10 November 2025, sought medical care at a clinic, and was diagnosed with pneumonia. 

- He was subsequently admitted to the national hospital in Phnom Penh on 13 November. 

- Samples were collected on the same day and tested positive for avian influenza A(H5N1) on 15 November. 

- His condition deteriorated rapidly, and he died the same day.   

- Investigations conducted in the case's hometown in Kampong Cham Province, which he visited between 4 and 6 November, revealed that the case had apparently healthy domestic birds (chickens and ducks) in his house. 

- However, sick and dead poultry had been reported in the village since 15 October. 

- Samples collected from two ducks and one chicken in the village tested positive for influenza A(H5N1). 

- Enhanced public health surveillance was implemented. 

- Among the case’s contacts, one was symptomatic, and all contacts tested negative for influenza A(H5N1).  

- Eighteen human infections with A(H5N1) viruses have been confirmed in Cambodia in 2025 and nine of these have been fatal. 

- All these cases in 2025 had exposure to domestic birds or their environments. 

- In some cases, domestic birds were reported to be sick or dead. 

- Where the information is available, the genetic sequence data from the viruses from the human cases closely matches that from recent local animal viruses and are identified as clade 2.3.2.1e viruses. 

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

A(H5N5), United States of America 

- On 15 November 2025, the United States of America (US) notified WHO of a confirmed human infection with influenza A(H5). 

- The patient was an adult with underlying medical conditions residing in Washington State. 

- The patient developed symptoms including fever during the week ending 25 October 2025. 

- During the week ending 8 November 2025, the patient was hospitalized with a serious illness and subsequently died on 21 November.  

- Respiratory specimens collected at the healthcare facility tested positive for influenza A virus by reverse-transcription-polymerase chain reaction (RT-PCR) and were presumptive positive for influenza A(H5) at the laboratory at the University of Washington. 

- The specimens were sent to the Washington State Public Health Laboratory, where influenza A(H5) was confirmed with the US Centers for Disease Control and Prevention (CDC) influenza A(H5) assay. 

- The sample was received at the CDC on 19 November. Sequencing conducted at the University of Washington and at the CDC indicated this was an influenza A(H5N5) virus belonging to the H5 haemagglutinin (HA) clade 2.3.4.4b.  

- Public health investigation revealed that the patient kept backyard poultry and domestic birds. 

- Additional epidemiological investigations were under way at the time of notification and included active monitoring of anyone who was in close contact with the patient.{7,8} 

- This is the first human case of this subtype reported globally. 

- Human infections with A(H5N1), A(H5N2), A(H5N6) and A(H5N8) have been reported previously. 

- A(H5N5) virus infections in animals have been detected and reported. 

- HPAI A(H5) clade 2.3.4.4b A(H5N5) viruses have been detected in North America in wild birds and wild mammals since at least 2023.{9} 

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

- Infections in non-human mammals are also reported, including in marine and land mammals.{10} 

- A list of bird and mammalian species affected by HPAI A(H5) viruses is maintained by FAO.{11}

-- Risk Assessment for avian influenza A(H5) viruses:  

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

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

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

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

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

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

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

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

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

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

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

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

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

A(H9N2), China  

- Since the last risk assessment of 5 November 2025, China notified WHO of four cases of infection with influenza A(H9N2) on 6 November 2025 and three cases on 12 December 2025. 

- All but two cases were in children. 

- Cases were detected in Guangdong (one), Guangxi (three), Henan (one) and Hubei (two) provinces. 

- The cases had onsets of symptoms in September, October and November 2025. 

- Four cases had reported exposure to backyard poultry, two had exposure to live poultry markets and the source of exposure for one case was under investigation at the time of reporting. 

- All cases had mild illness and recovered, except one in an elderly person with underlying conditions who was hospitalized at the time of reporting with severe pneumonia. 

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

- A(H9) viruses were detected in environmental samples collected during the investigations around some of the cases. 

-- Risk Assessment for avian influenza A(H9N2):   

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

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

- Most human infections of A(H9N2) to date have resulted in mild clinical illness. 

- Since the virus is endemic in poultry in multiple countries in Africa and Asia, further human cases associated with exposure to infected poultry are expected but remain unusual. 

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

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

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

- At the present time, no sustained human-to-human transmission has been identified associated with the 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, therefore sustained human-to-human transmission is thus currently considered unlikely.   

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

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

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

Swine influenza viruses in humans 

Influenza A(H1N1)v, China 

- Since the last risk assessment of 5 November 2025, the detection of a Eurasian avian-like swine influenza A(H1N1)v virus in a human was reported from China on 12 December 2025. 

- A 60-year-old male from Yunnan province had onset of mild illness on 2 November 2025, was hospitalized on 6 November and discharged on 10 November. 

- He had reported exposure to backyard pigs. 

Influenza A(H1N2)v, USA 

- A human case of infection with an influenza A(H1N2)v virus was detected in the state of Vermont in an adult who had an onset of symptoms in early October. 

- The individual was briefly hospitalized and has recovered. 

- The investigation conducted by state public health officials was unable to determine the likely source of exposure or if close contacts developed symptoms. 

- According to the report, no human-to-human transmission was identified associated with this case.{12}  

-- 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. 

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

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

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

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

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

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

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

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

Overall risk management recommendations: 

-- Surveillance and investigations

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

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

• Countries should increase avian influenza surveillance in: 

- domestic and wild birds,

- enhance surveillance for early detection in cattle populations in countries where HPAI is known to be circulating, 

- include HPAI as a differential diagnosis in non-avian species, including cattle and other livestock populations, with high risk of exposure to HPAI viruses; 

- monitor and investigate cases in non-avian species, including livestock, report cases of HPAI in all animal species, including unusual hosts, to WOAH and other international organizations, 

- share genetic sequences of avian influenza viruses in publicly available databases, 

- implement preventive and early response measures to break the HPAI transmission cycle among animals through movement restrictions of infected livestock holdings and strict biosecurity measures in all holdings, 

- employ good production and hygiene practices when handing animal products, and protect persons in contact with suspected/infected animals.{13} 

- More guidance can be found from WOAH and FAO. 

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

- Enhanced surveillance should consider the health care seeking behaviour of the population, and could include a range of active and passive health care and/or communitybased approaches, including: 

> enhanced surveillance in local influenza-like illness (ILI)/SARI systems, 

> active screening in hospitals and of groups that may be at higher occupational risk of exposure, and 

> inclusion of other sources such as traditional healers, private practitioners and private diagnostic laboratories. 

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

-- Notifying WHO 

• All human infections caused by a new subtype of influenza virus are notifiable under the International Health Regulations (IHR, 2005).{14} State Parties to the IHR (2005) are required to immediately notify WHO of any laboratory-confirmed{15} case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic{16}. 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{17} with a WHO Collaborating Centre for influenza of GISRS. The viruses are used by the public health laboratories to assess the risk of pandemic influenza and to develop candidate vaccine viruses.  

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

-- Risk reduction 

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

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

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

-- Trade and travellers 

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

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

Links:  

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

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

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

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

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

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

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

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

-- OFFLU http://www.offlu.org/ 

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

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

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

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

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

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

{7} World Health Organization (5 December 2025). Disease Outbreak News; Avian Influenza A(H5N5)- United States of America. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2025DON590. 

{8} US CDC FluView. Weekly US Influenza Surveillance Report: Key Updates for Week 46, ending November 15, 2025. Available at https://www.cdc.gov/fluview/surveillance/2025-week-46.html. 

{9} Erdelyan CNG, Kandeil A, Signore AV, et al. Multiple transatlantic incursions of highly pathogenic avian influenza clade 2.3.4.4b A(H5N5) virus into North America and spillover to mammals. Cell Rep. 2024 Jul 23;43(7):114479. doi:10.1016/j.celrep.2024.114479. Epub 2024 Jul 13. PMID:39003741; PMCID:PMC11305400. 

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

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

{12} US CDC FluView. Weekly US Influenza Surveillance Report: Key Updates for Week 46, ending November 15, 2025. Available at https://www.cdc.gov/fluview/surveillance/2025-week-46.html. 

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

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

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

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

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

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Source: 

Link: https://www.who.int/publications/m/item/influenza-at-the-human-animal-interface-summary-and-assessment--19-december-2025

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#UK {#Scotland} - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

 

~155K laying chickens’ flock. Samples taken were positive for HPAI H5N1. Birds presented clinical signs prior to testing.

Source: 

Link: https://wahis.woah.org/#/in-review/7139

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#Remdesivir as a potent #antiviral against prototype and current #epidemic #Oropouche virus #strains (BeAn19991 and PE-IAM4637)

 

Highlights

• We generated a recombinant reporter OROV that expresses the eGFP fluorescent protein in infected cells.

• We found that remdesivir efficiently inhibited the replication of Oropouche virus (OROV) using this reporter OROV.

• We demonstrated strain-dependent differences in the replication efficiency of OROV.

Abstract

The Oropouche virus (OROV), an orthobunyavirus transmitted by biting midges, is the causative agent of Oropouche fever, which has caused multiple outbreaks in South and Central America. During the most recent epidemic in 2023–2025, more than 25,000 laboratory-confirmed cases were reported in Brazil, and no licensed antivirals have been reported to be effective date. In this study, we generated a recombinant OROV-expressing enhanced green fluorescent protein (rOROV/GFP) to facilitate rapid and sensitive antiviral evaluation. Growth kinetics demonstrated that rOROV/GFP replicated less efficiently than wild-type rOROV and that the historical prototype strain (BeAn19991) exhibited higher replication efficiency than the recent epidemic isolate (PE-IAM4637) in both Vero E6 and Huh7 cells. Using this system, we evaluated the antiviral activity of ribavirin, favipiravir (T-705), and remdesivir against OROV. All three compounds inhibited OROV replication in a dose-dependent manner, with remdesivir showing the greatest potency (IC₅₀ values of 0.31 µM). Taken together, our findings highlight remdesivir as a promising candidate for the treatment of Oropouche fever caused by OROV. Furthermore, we established rOROV/GFP as a powerful tool for antiviral drug screening.

Source: 

Link: https://www.sciencedirect.com/science/article/pii/S0168170225001583?via%3Dihub

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The angel of the abyss and the infernal locusts, Ende (c. 975)

 

Public Domain.

Source: 

Link: https://www.wikiart.org/en/ende/the-angel-of-the-abyss-and-the-infernal-locusts-975

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#Influenza PA #Substitutions and Genetic Diversity of #H1N1pdm09, #H3N2, and B/Victoria Viruses in #Japan During the 2023–2024 Season

 

Abstract

We characterized influenza A(H1N1)pdm09, A(H3N2), and B/Victoria viruses circulating in Japan during 2023–2024, focusing on lineage placement relative to WHO-recommended vaccine strains and on baloxavir resistance (PA/I38T substitutions). We enrolled 210 outpatients with influenza-like illness across eight clinics in six prefectures (October 2023–September 2024). Of these, 209 had an analyzable pre-treatment respiratory specimen for RT-PCR; hemagglutinin (HA) and neuraminidase (NA) genes were sequenced by next-generation sequencing (NGS). PA/I38T substitutions that confer baloxavir resistance were assessed by cycling-probe RT-PCR, Sanger sequencing, and NGS. HA phylogenies were constructed with global datasets and WHO vaccine reference strains. Of 209 pre-treatment specimens, 181 were influenza-positive (A(H1N1)pdm09 44.2%, A(H3N2) 37.6%, B/Victoria 18.2%); 51 follow-up specimens were collected ≈4–5 days after baloxavir or neuraminidase inhibitor therapy. HA phylogeny placed A(H1N1)pdm09 in clades 5a.2a/5a.2a.1 with predominance of subclade D.2. A(H3N2) clustered exclusively in clade 2a.3a.1 (J lineage, mostly J.1), indicating a mismatch with the season’s A/Darwin/9/2021 vaccine component and supporting the subsequent J-lineage update. All B/Victoria genomes fell within V1A.3a.2 on a C.5 backbone (C.5.1 and C.5.7). No PA/I38T variant was detected in any pre-treatment specimen. Post-baloxavir, PA/I38T emerged in one A(H3N2) case (confirmed by all three methods) and in one B/Victoria case detected by NGS only (minority variant in a low-load sample). NA genes showed no substitutions associated with reduced susceptibility to laninamivir (e.g., E119A, G147E). During 2023–2024, A(H1N1)pdm09 and B/Victoria remained genetically aligned with their vaccine components, whereas A(H3N2) shifted to the J lineage, consistent with the 2024–2025 vaccine update. Although pre-treatment PA/I38T was absent, low-frequency on-therapy selection was observed, including a rare PA/I38T in influenza B/Victoria detected by NGS, suggesting the value of deep sequencing when viral loads are low. These integrated genomic–clinical data support vaccine strain realignment for H3N2 and continued monitoring of baloxavir resistance in outpatient care.

Source: 

Link: https://www.mdpi.com/1999-4915/18/1/13

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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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Effectiveness of #nirmatrelvir/ritonavir and #molnupiravir in reducing the #risk of short-term and long-term #cardiovascular complications of #COVID19: a target trial emulation study

 

Abstract

While treatment with nirmatrelvir/ritonavir or molnupiravir is effective in lowering the rate of severe COVID-19, the effectiveness of these antivirals in reducing the risk of cardiovascular outcomes, especially among the hospitalized population, remains largely unknown. In this study, we assessed the real-world effectiveness of nirmatrelvir/ritonavir and molnupiravir on short- and long-term cardiovascular complications of COVID-19 using a target trial emulation design. Two target trials of COVID-19 antivirals were emulated by using a territory-wide, population-based, retrospective cohort of hospitalized patients in Hong Kong. Nine cardiovascular outcomes were evaluated in both short-term (day 0–21) and long-term (day 22–365) post-SARS-CoV-2 infection. Compared with the control group, the use of nirmatrelvir/ritonavir was associated with a significantly lower one-year risk of cardiovascular mortality, composite cardiovascular complications, major adverse cardiac events, cerebrovascular disorders, dysrhythmia, ischemic heart disease, and other cardiac disorders following infection. Molnupiravir use was associated with a short-term risk reduction in cardiovascular complications, but only a marginal risk reduction in long-term cardiovascular mortality among other complications. This study demonstrated the effectiveness of nirmatrelvir/ritonavir in reducing the risks of short- and long-term cardiovascular complications following a SARS-CoV-2 infection among the hospitalized population. Our findings suggested health-related benefits of prescribing nirmatrelvir/ritonavir over molnupiravir against severe cardiovascular post-acute sequelae of COVID-19 in the long term.

Source: 

Link: https://www.nature.com/articles/s41467-025-67776-4

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#Serological evidence of concurrent #Lassa virus and #SARS-CoV-2 #exposure in #Ghana- a cross-sectional study

 

Abstract

Background

The COVID-19 pandemic has exposed vulnerabilities in infectious disease surveillance, especially in West Africa where endemic viruses including Lassa fever persist. The overlapping clinical symptoms of these two infections create diagnostic challenges and the possibility of undetected co-infections.

Methods

A retrospective cross-sectional study was conducted using archived serum samples from a nationwide SARS-CoV-2 seroprevalence survey in Ghana. 434 samples across six regions were tested for SARS-CoV-2 total antibodies (IgG/IgM) using the WANTAI ELISA kit and Lassa virus IgG using ReLASV Pan-Lassa-NP-IgG ELISA.

Results

SARS-CoV-2 antibody prevalence was 64.29% (n = 279) and Lassa virus IgG prevalence was 20.28% (n = 88). Of the cohort of subjects who were seropositive for SARS-CoV-2, 20.79% were also seropositive for LASV IgG. Multivariate analysis revealed household size as a strong risk factor of dual exposure. Individuals from medium-sized households (4–6 persons) (aOR = 8.78, 95% CI: 1.18–65.56, p = 0.034) and large households (≥ 7 persons) (aOR = 12.90, 95% CI: 1.99–83.40, p = 0.007) had significantly increased odds of dual seropositivity compared to small households. Regional variations were observed, with Greater Accra showing significantly lower odds of dual seropositivity (aOR = 0.13, 95% CI: 0.03–0.51, p = 0.004) compared to Ashanti Region.

Conclusion

This study provides serological evidence of SARS-CoV-2 and Lassa virus concurrent exposure in Ghana during the COVID-19 pandemic. This finding suggests large household size as a key driver of dual viral exposure and calls for integrated surveillance systems and targeted interventions in large household settings to reduce concurrent transmission of viruses with pandemic potential.

Source: 

Link: https://link.springer.com/article/10.1186/s12879-025-12385-1

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