Detection of #antibodies against #H5 subtype highly pathogenic avian #influenza viruses in multiple #raccoons in Tokachi District, #Hokkaido, #Japan, from 2022 to 2023

Abstract

In recent years, infection cases of H5 subtype highly pathogenic avian influenza viruses (HPAIVs) in wild mammals have increased globally. To obtain recent epidemiological information regarding influenza A virus (IAV) infection in raccoons (Procyon lotor), the prevalence of anti-IAV antibodies in sera was analyzed among raccoons captured in Tokachi District, Hokkaido, Japan, from 2019 to 2023. Screening of serum samples using enzyme-linked immunosorbent assay and agar gel precipitation test detected anti-IAV antibodies in 5 of 114 (4.4 %) raccoons. All positive sera were from raccoons captured from 2022 to 2023. The hemagglutination inhibition test revealed that all five serum samples contained anti-H5 subtype HPAIV antibodies, and one also contained anti-H1 subtype antibodies. The neuraminidase inhibition test revealed that all five sera contained anti-N1 subtype antibodies, and one also contained anti-N8 subtype antibodies. In the virus neutralization test, these five sera showed stronger neutralization activity against the H5 subtype clade 2.3.4.4b HPAIV strain recently circulating worldwide compared to the old H5 HPAIV strain isolated in Japan in 2007. These findings suggested that raccoons could be involved in the circulation of H5 HPAIVs in nature.

Source: Virus Research, https://www.sciencedirect.com/science/article/pii/S0168170224002089?via%3Dihub

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Susceptibility of #bovine respiratory and mammary epithelial #cells to avian and #mammalian derived clade 2.3.4.4b #H5N1 highly pathogenic avian #influenza viruses

Abstract

Zoonotic transmission of avian influenza viruses into mammals is relatively rare due to anatomical differences in the respiratory tract between species. Recently, clade 2.3.4.4b highly pathogenic H5N1 avian influenza viruses were detected circulating in North American cattle. Sporadic transmission between cattle, humans, and other animals proximal to cattle or after consuming products from infected cattle has occurred, but thus far there is no evidence of human-to-human transmission. However, the virus has the potential to adapt to the mammalian respiratory tract with every transmission event that occurs, making it crucial to understand cellular and species tropism of the H5N1 2.3.4.4b viruses. We compared viral kinetics of clade 2.3.4.4b viruses isolated from birds and mammals in respiratory epithelial cells derived from cattle, human, swine, and ferret. We found that avian derived viruses could replicate in swine cells only, yet mammalian derived strains could replicate efficiently in all tracheal and nasal epithelial cells tested. Interestingly, only bovine mammary epithelial cells (MEC) and swine respiratory epithelial cells were permissive to both avian and mammalian derived strains, possibly due to increased sialic acid expression on bovine MEC compared to bovine tracheal epithelial cells (TEC). However, sialic acid expression differed between dairy and beef cows: TEC derived from a dairy cow had increased expression of alpha2,6;2,3 sialic acid receptors compared to TEC from a beef-dairy cow cross. This study highlights the ability of clade 2.3.4.4b H5N1 viruses derived from mammals but not wild birds to infect the respiratory epithelium of other mammalian hosts.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.01.09.632235v1?rss=1

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Asymptomatic #infection and #antibody #prevalence to co-occurring avian #influenza viruses vary substantially between sympatric #seabird species following #H5N1 #outbreaks

Abstract

Emerging infectious diseases are of major concern to animal and human health. Recent emergence of high pathogenicity avian influenza virus (HPAIV) (H5N1 clade 2.3.4.4b) led to substantial global mortality across a range of host species. Co-occurring species showed marked differences in mortality, generating an urgent need for better epidemiological understanding within affected populations. We therefore tested for antibodies, indicative of previous exposure and recovery, and for active viral infection in apparently healthy individuals (n = 350) across five co-occurring seabird species on the Isle of May, Scotland, during 2023, following H5N1 HPAIV associated mortality in the preceding summer. Antibody prevalence to AIV subtypes varied substantially between species, ranging from 1.1% in European shags (Gulosus aristotelis) (to H5) to 78.7% in black-legged kittiwakes (Rissa tridactyla) (to H16 or both H13 and H16), and between 31 and 41% for three auk species (H5, H16 or both). At least 20.4% of auks had antibodies to an as yet unidentified subtype, suggesting further subtypes circulating in the population. We found low levels of active, but asymptomatic, AIV infection in individuals (1.6–4.5%), but excluded this as H5N1. Our results emphasise the importance of testing healthy individuals to understand the prevalence of co-circulating AIV subtypes in wild populations, and the potential for future reassortment events which could alter virus behaviour and impact.

Source: Scientific Reports, https://www.nature.com/articles/s41598-025-85152-6

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#Iceland, Avian #influenza #H5N5 in #cats

 {Original text in Icelandic, translated, edited.}

The Icelandic University of Iceland's Pathology Laboratory at Keldur notified the Icelandic Food and Veterinary Authority on January 6 that a kitten that arrived at the laboratory for autopsy had been diagnosed with a severe strain of avian influenza (H5N5). 

This is the same strain that has been detected in wild birds in Iceland since September last year and on one poultry farm in early December. 

The Icelandic Food and Veterinary Authority immediately issued instructions for disease control to prevent the spread of the infection and is now working to trace the infection. 

Symptoms of the disease in this cat included loss of appetite, weakness, stiffness, tremors, seizures and other neurological symptoms. 

Cat owners are asked to contact a veterinarian immediately if they notice such symptoms in their cats.

The cat diagnosed with bird flu was a 10-week-old kitten that died on December 22. The littermate the kitten was from and another kitten from the same litter died after a short illness two days earlier. They were not tested. 

The kitten's other littermates had left the home before the illness occurred and are all asymptomatic today. 

The cats are from Ísafjörður, but the kitten diagnosed with the infection had arrived in Reykjavík. The owners of all the cats have been contacted.

The Icelandic Food and Veterinary Authority believes that it is most likely that the cats were infected by an infected wild bird. 

At present, there is no evidence of infection in more cats, but the Icelandic Food and Veterinary Authority asks cat owners and veterinarians to be on the lookout for symptoms that may indicate avian influenza infection. 

There have been a number of diagnoses in wild birds in recent months, and therefore there is some risk that cats can become infected while hunting or from carcasses they come across. 

However, the Icelandic Food and Veterinary Authority does not believe the risk is so great that there is reason to warn against letting cats outside. 

People are, however, reminded to always maintain general hygiene when interacting with animals and caring for them. 

General information about avian influenza and guidelines for disease prevention can be found on the website of the Directorate of Health . 

It is worth noting that the risk of infection for people caused by the avian influenza virus is low, according to information on the website of the European Centre for Disease Prevention and Control (ECDC) .

In recent years, avian influenza has been increasingly detected in various species of mammals around the world. The most common type is the highly pathogenic H5N1 strain. This trend clearly demonstrates the virus's ability to adapt to new animal species. One of the greatest concerns worldwide is the current outbreak of avian influenza in dairy cows in the United States caused by the highly pathogenic H5N1 strain. However, the genotype of the virus in question has not yet been identified anywhere else in the world. Detailed information about this can be found on the websites of the United States Department of Agriculture USDA and the United States Centers for Disease Control and Prevention ( CDC) .

Few cases of the virulent H5N5 strain have been reported in mammals. This strain has been mainly found in wild birds in the Arctic, but last year it was also found in red foxes and lynx in Norway, otters in the Netherlands, lynxes in Finland, and red foxes, skunks, and raccoons in Canada. No cases of this strain in domestic animals have been reported to the World Organisation for Animal Health (WOAH) to date.

In recent years, WOAH has placed great emphasis on combating the spread of avian influenza and published on its website in December a call for all nations of the world to place greater emphasis on monitoring and actions to prevent the spread of dangerous avian influenza viruses.

The Icelandic Food and Veterinary Authority reiterates its recommendation to the public to report wild birds and wild mammals found dead, when the cause of death is not obvious. This is best done by registering a tip on the Icelandic Food and Veterinary Authority website. It is important to clearly describe the location, preferably by recording coordinates.

(...)

Source: MAST, https://www.mast.is/is/um-mast/frettir/frettir/fuglainfluensa-i-ketti

Highly pathogenic avian #H5N1 #influenza A virus #replication in ex vivo #cultures of #bovine mammary #gland and teat tissues

{Excerpt}

Our data indicate that bovine H5N1 viruses can replicate efficiently in the epithelium of the bovine teat cistern, suggesting that they invade the mammary gland through the teat canal, which is more easily accessed by viruses. H5N1 virus is thought to be transmitted among lactating dairy cattle through contaminated milking equipment and/or milker's hands during milking[23]. Proper milking procedures are required to prevent spread of HPAI H5N1 viruses in dairy cattle, thereby minimizing the risk of transmission from cows to other mammals including humans.

Source: Emerging Microbes and Infections, https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2450029#d1e346

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#Philippines - High pathogenicity avian #influenza #H5N2 viruses (#poultry) (Inf. with) - Immediate notification

Backyard reared poultry in Camarines Norte Region.

Source: WOAH, https://wahis.woah.org/#/in-review/6167

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#Iceland - #Influenza A #H5N5 viruses of high pathogenicity (Inf. with) ({household #cats}) (2017-) - Immediate notification [FINAL]

Three cats (one adult female and two 10 week old kittens) from the same household died on December 20., 21. and 22. after they had been ill for only a few days. The main clinical signs were lethargy, anorexia, cramps and stiffness. Other kittens from the same litter had been rehomed before those three got sick and they have not shown any symptoms. The most probable source of infection is wild birds. HPAI H5N5 have been diagnosed in a few wild birds in Iceland since September last year.

Source: WOAH, https://wahis.woah.org/#/in-review/6168

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#Greenland - #Influenza A #H5N5 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 A wild Northern Fulmar in Danish Exclusive Economic Zone (Greenland).

Source: WOAH, https://wahis.woah.org/#/in-review/6172

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#Evidence of avian and human #influenza A virus #infection in farmed Siamese #crocodiles (Crocodylus siamensis) in #Thailand

Abstract

Crocodilians are susceptible to a range of virus infection including influenza A virus (IAV). However, little is known about the ecology and epidemiology of IAV in crocodile species. This study aimed to investigate IAV infection in farmed Siamese crocodiles in central Thailand. We collected plasma samples and pharyngeal swab samples from Siamese crocodiles residing in 13 crocodile farms in 9 provinces of central Thailand during 2019. Additional archival plasma samples of Siamese crocodiles collected in 2012 and 2018 were also included in the study. Plasma samples were screened for influenza A antibodies by a hemagglutination inhibition (HI) assay and positive were evaluated by a cytopathic effect/hemagglutination based-microneutralization (MN) assay. Swab samples were tested for influenza viral RNA by a real-time RT-PCR assay targeting the influenza matrix (M) gene. Among 246 tested plasma samples, the overall seroprevalence of antibodies against IAV in farmed Siamese crocodiles was 17.5% (43/246). The most common hemagglutinin (HA) subtype was H2 (46.5%, 20/43) followed by H9 (39.5%, 17/43), human H1 (14%, 6/43) and H1 (7%, 3/43). Multiple HA subtypes were also detected in 7% (3/43) of infected crocodiles with combination of H1 and H2 subtypes. All 126 tested swab samples were negative for influenza viral RNA. In addition, we demonstrated the ability of wild-type IAV subtypes (H1, H2, H9 and human H1) to infect primary Siamese crocodile fibroblast cells. To our knowledge, this is the first report of serological evidences of avian and human IAV infection in Siamese crocodiles. Our findings highlighted the role of crocodile species in the ecology of IAV particularly the potential to serve as the reservoir or mixing vessel for the viruses that significantly threaten both human and animal health.

Source: PLoS One, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0317035

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Long-term immune responses induced by low-dose #infection with high pathogenicity avian #influenza viruses can protect #mallards from reinfection with a heterologous strain

Abstract

Migratory water birds are considered to be carriers of high pathogenicity avian influenza viruses (HPAIVs). In Japan, mallards are often observed during winter, and HPAIV-infected mallards often shed viruses asymptomatically. In this study, we focused on mallards as potential carriers of HPAIVs and investigated whether individual wild mallards are repeatedly infected with HPAIVs and act as HPAIV carriers multiple times within a season. Mallards were experimentally infected with H5N1 and H5N8 HPAIVs that were isolated recently in Japan and phylogenetically belong to different hemagglutinin groups (G2a, G2b, and G2d). All of these strains are more infectious to mallards than to chickens, and the infected mallards shed enough virus to infect others, regardless of whether they exhibited clinical signs. Serum antibodies to the homologous antigen, induced by a single infection with a low virus dose (10 times the 50% mallard infectious dose), were maintained at detectable levels for 84 days. Immunity at 84 days post-inoculation fully protected the mallards from a challenge with the homologous strain, as demonstrated by a lack of viral shedding, and antibody levels did not increase significantly in most of these birds. Protection against heterologous challenge was also observed despite undetectable levels of antibodies to the challenge strain. Our findings suggest that repeated infections with homologous and heterologous HPAIV strains do not occur frequently in individual wild mallards within a season, particularly at low viral doses, and the frequency with which they act as carriers may be limited.

Source: Archives of Virology, https://link.springer.com/article/10.1007/s00705-024-06209-x

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#Comparison of Contemporary and Historic Highly Pathogenic Avian #Influenza A(#H5N1) Virus #Replication in #Human #Lung #Organoids

Abstract

We compared virus replication and host responses in human alveolar epithelium infected with highly pathogenic avian influenza (HPAI) A(H5N1) viruses. A/Vietnam/1203/2004 replicated most efficiently, followed by A/Texas/37/2024, then A/bovine/Ohio/B24OSU-342/2024. Induction of interferon-stimulated genes was lower with A/Texas/37/2024 and A/bovine/Ohio/B24OSU-342/2024, which may indicate a reduced disease severity of those viruses.

Source: Emerging Infectious Diseases Journal, https://wwwnc.cdc.gov/eid/article/31/2/24-1147_article

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#Information for #Workers Exposed to #H5N1 #Birdflu {virus}

 {Summary}

At a glance

-- H5N1 bird flu is caused by viruses that can infect cows and other animals but most commonly affect birds and poultry. 

-- People who work with infected animals or their byproducts (for example, raw milk), might get sick from the virus. 

-- For example, dairy and poultry workers might get sick with H5N1 bird flu. 

-- Your employer should develop a workplace health and safety plan and share it with you. 

-- CDC updated this page to add information about worker exposure levels (low, medium, and high). 

-- We also added detail about how to use the right personal protective equipment safely for each exposure level.

(...)

Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/bird-flu/prevention/farm-workers.html

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#Surveillance of Highly Pathogenic Avian #Influenza Virus in Wild #Canids from #Pennsylvania, #USA

Abstract

The avian influenza virus is a global pathogen with significant health and economic implications. While primarily a pathogen of wild and domestic birds, recent outbreaks of the H5N1 highly pathogenic avian influenza virus (HPAIV) clade 2.3.4.4b have caused mortality in a wide variety of mammals, including members of the Canidae family, on multiple continents. Despite sporadic mortality events globally, the epidemiology and pathobiology of H5N1 HPAIV in wild canids remains poorly defined. During 2022–2024, 41 wild canid carcasses (diagnostic cases), including 23 red foxes and 18 gray foxes, were tested for the influenza A virus (IAV) via PCR, with five red fox kits testing positive (12%). Infected animals had variably severe encephalitis, pneumonia, and occasionally myocarditis associated with strong immunolabeling for IAV. Serum from 269 wild canids in Pennsylvania was tested for antibodies to IAV, including 133 samples collected prior to 2021 (pre-H5N1 HPAIV 2.3.4.4b introduction) and 136 collected after 2022 (post-H5N1 HPAIV 2.3.4.4b introduction). All samples collected prior to 2021 were seronegative for IAV. Two coyotes from 2024 were seropositive for IAV but were negative for antibodies to the H5 and N1 subtypes. Collectively, these data suggest that while sporadic H5N1 HPAIV infection and mortality can occur in wild canids, particularly juvenile red foxes, infection was limited in these outwardly healthy and opportunistically sampled animals. Future studies should utilize a risk-based approach to target sampling of wild canids at increased risk for H5N1 HPAIV infection, such as those around waterfowl habitats or spatially around wild bird or domestic animal outbreaks.

Source: Animals, https://www.mdpi.com/2076-2615/14/24/3700

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#Analysis of the Monophyletic #Lineage of Avian #Influenza #H5N1 Which Circulated in #Venezuelan #Birds During the 2022–2023 #Outbreak

Abstract

Avian influenza subtype H5N1 has caused outbreaks worldwide since 1996, with the emergence of the Guandong lineage in China. The current clade 2.3.4.4b has evolved from this lineage, with increased virulence and mass mortality events in birds and mammals. The objective of this study was the analysis of 17 viral genomes of H5N1 avian influenza isolated in Venezuela during the 2022–2023 outbreak. The eight viral genomic segments were amplified using universal primers and sequenced via next-generation sequencing. The sequences were analyzed to confirm the H5 hemagglutinin clade, identify possible genetic reassortments, and perform a phylogenetic and docking analysis of the viral isolates. The viruses found in Venezuela belonged, as expected, to clade 2.3.4.4b and formed a monophyletic clade with North American influenza viruses, with no evidence of further reassortment. The introduction of the virus in South America is associated with bird migration through the Atlantic (Venezuela), Atlantic/Mississippi (Choco, Colombia), and Pacific migratory flyways, with the emergence of several viral lineages. Several mutations were found in all segments of the genome, although none of the key mutations was involved in mammalian adaptation. Moreover, in silico structural analysis suggests, as expected, that the viral hemagglutinin maintained a predilection for avian α2,3-linked sialic acid. The unprecedented pathogenic outbreak of avian influenza disease in South America was associated with the circulation of three different lineages, which maintain a lower affinity for the mammalian receptor.

Source: Microorganisms, https://www.mdpi.com/2076-2607/12/12/2519

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#Genetic and #Molecular Characterization of Avian #Influenza A(#H9N2) Viruses from Live #Bird #Markets (LBM) in #Senegal

Abstract

Despite extensive experience with influenza surveillance in humans in Senegal, there is limited knowledge about the actual situation and genetic diversity of avian influenza viruses (AIVs) circulating in the country, hindering control measures and pandemic risk assessment. Therefore, as part of the “One Health” approach to influenza surveillance, we conducted active AIV surveillance in two live bird markets (LBMs) in Dakar to better understand the dynamics and diversity of influenza viruses in Senegal, obtain genetic profiles of circulating AIVs, and assess the risk of emergence of novel strains and their transmission to humans. Cloacal swabs from poultry and environmental samples collected weekly from the two LBMs were screened by RT-qPCR for H5, H7, and H9 AIVs. Subsequently, a subset of H9-positive samples was selected for whole sequencing. From December 2023 to October 2024, 499 samples were tested, and AIV was detected in 58.3% of them. Among these, A/H9N2 was the only subtype detected in both markets, with a detection rate of 47.7% (82/172) in Thiaroye and 35.3% (42/119) in Tilene, resulting in an overall positivity rate of 42.6% (124/291). Genome sequencing of 22 A/H9N2 isolates, including 11 poultry drinking water samples, 7 carcass wash water samples, 3 fecal samples, and 1 cloacal swab, yielded 7 complete and 15 partial genomic sequences. Phylogenetic analyses of the resulting sequences showed that the A/H9N2 isolates obtained in this study formed a monophyletic cluster and were closely related to the Senegalese human strain (A/Senegal/0243/2019) identified through the national influenza sentinel surveillance program. These strains were also closely related to the A/H9N2 viruses of the G1 lineage circulating in neighboring countries, suggesting cross-border transmission. The A/H9N2 strains carried the low pathogenicity RSSR/GLF motif at the HA cleavage site and possessed several key amino acid mutations, including HA-I155T and HA-Q226L, which are associated with human host adaptation, PB2-T105V, PB2-A661T, and PB2-A588V, which are linked to the human-to-human transmission and increased polymerase activity, NS2-T14M, NS2-M100I, NS1-I106M, NS1-V222M, NS1-E223A, NS1-I226V, NS1-E227G, and NS1-P228S, which are known to alter virulence (increased or reduced) in humans or mice, and M2-S31N, which promotes drug resistance. Seven potential N-glycosylation sites were predicted in the HA protein and six in the NA protein. The selection pressure analysis revealed that the A/H9N2 isolates were primarily under neutral evolution or purifying selection pressure. Overall, our findings highlight the potential for cross-species transmission of Senegalese A/H9N2 viruses, emphasizing the need for sustained monitoring of these viruses in both animal and human populations.

Source: Viruses, https://www.mdpi.com/1999-4915/17/1/73

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#Disruption of seasonal #influenza #circulation and #evolution during the 2009 #H1N1 and #COVID19 #pandemics in Southeastern #Asia

Abstract

East, South, and Southeast Asia (together referred to as Southeastern Asia hereafter) have been recognized as critical areas fuelling the global circulation of seasonal influenza. However, the seasonal influenza migration network within Southeastern Asia remains unclear, including how pandemic-related disruptions altered this network. We leveraged genetic, epidemiological, and airline travel data between 2007-2023 to characterise the dispersal patterns of influenza A/H3N2 and B/Victoria viruses both out of and within Southeastern Asia, including during perturbations by the 2009 A/H1N1 and COVID-19 pandemics. During the COVID-19 pandemic, consistent autumn-winter movement waves from Southeastern Asia to temperate regions were interrupted for both subtype/lineages, however the A/H1N1 pandemic only disrupted A/H3N2 spread. We find a higher persistence of A/H3N2 than B/Victoria circulation in Southeastern Asia and identify distinct pandemic-related disruptions in A/H3N2 antigenic evolution between two pandemics, compared to interpandemic levels; similar patterns are observed in B/Victoria using genetic distance. The internal movement structure within Southeastern Asia markedly diverged during the COVID-19 pandemic season, and to a lesser extent, during the 2009 A/H1N1 pandemic season. Our findings provide insights into the heterogeneous impact of two distinct pandemic-related disruptions on influenza circulation, which can help anticipate the effects of future pandemics and potential mitigation strategies on influenza dynamics.

Source: Nature Communications, https://www.nature.com/articles/s41467-025-55840-y

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#Trends of acute respiratory #infection, including human #metapneumovirus, in the Northern Hemisphere

Situation at a glance

In many countries of the Northern Hemisphere, trends in acute respiratory infections increase at this time of year. 

These increases are typically caused by seasonal epidemics of respiratory pathogens such as seasonal influenza, respiratory syncytial virus (RSV), and other common respiratory viruses, including human metapneumovirus (hMPV), as well as mycoplasma pneumoniae. 

Many countries conduct routine surveillance for acute respiratory infections and common respiratory pathogens. 

Currently, in some countries in the temperate Northern hemisphere, influenza-like illness (ILI) and/or acute respiratory infection (ARI) rates have increased in recent weeks and are above baseline levels, following usual seasonal trends. 

Seasonal influenza activity is elevated in many countries in the Northern hemisphere. 

Where surveillance data is available, trends in RSV detections currently vary by region with decreases reported in most regions except in North America. 

Recently, there has been interest in hMPV cases in China including suggestions of hospitals being overwhelmed. 

hMPV is a common respiratory virus found to circulate in many countries in winter through to spring, although not all countries routinely test and publish data on trends in hMPV . 

While some cases can be hospitalized with bronchitis or pneumonia, most people infected with hMPV have mild upper respiratory symptoms similar to the common cold and recover after a few days. 

Based on data published by China, covering the period up to 29 December 2024, acute respiratory infections have increased during recent weeks and detections of seasonal influenza, rhinovirus, RSV, and hMPV, particularly in northern provinces of China have also increased. 

The observed increase in respiratory pathogen detections is within the range expected for this time of year during the Northern hemisphere winter. 

In China, influenza is the most commonly detected respiratory pathogen currently affecting people with acute respiratory infections. 

WHO is in contact with Chinese health officials and has not received any reports of unusual outbreak patterns. 

Chinese authorities report that the health care system is not overwhelmed and there have been no emergency declarations or responses triggered. 

WHO continues to monitor respiratory illnesses at global, regional and country levels through collaborative surveillance systems, and provides updates as needed.

Description of the situation

In many countries of the Northern Hemisphere, trends in acute respiratory infections increase at this time of year. These increases are typically caused by seasonal epidemics of respiratory pathogens such as seasonal influenza, RSV, and other common respiratory viruses, including hMPV, as well as mycoplasma pneumoniae. The co-circulation of multiple respiratory pathogens during the winter season can sometimes cause an increased burden on health care systems treating sick persons.

Currently, in some countries in the temperate Northern hemisphere, influenza-like illness (ILI) and/or acute respiratory infection (ARI) rates have increased in recent weeks and are above baseline levels, following usual seasonal trends. 

Influenza activity is elevated in many countries in Europe, Central America and the Caribbean, Western Africa, Middle Africa, and many countries across Asia, with the predominant seasonal influenza type and subtype varying by location, typical for this time of year, except during most of 2020 and 2021, when there was little influenza activity during the COVID-19 pandemic (...). 

SARS-CoV-2 activity as detected in sentinel surveillance and reported to Global Influenza Surveillance and Response System (GISRS), along with wastewater monitoring from the reporting countries, is currently low in countries in the Northern hemisphere following prolonged high level activity during summer months in the Northern hemisphere. 

Where surveillance data is available, trends in RSV activity are variable by region with downward trends observed in most subregions of the Americas, except in North America where RSV activity has increased, and decreases have been observed in the European region in recent weeks. Some countries conduct routine surveillance and report trends for other commonly circulating respiratory pathogens, such as hMPV, and report such information on a routine basis. Some countries in the Northern hemisphere have reported increased trends, varying by virus, in recent weeks, typical for this time of year.  

There has been international interest in a potential increase of respiratory virus transmission in China, particularly hMPV, including suggestions of hospitals being overwhelmed. China has an established sentinel surveillance system for ILI and severe acute respiratory infections (SARI), including hMPV, and conducts routine virological surveillance for common respiratory pathogens with detailed reports published weekly on the China Center for Disease Control and Prevention (CDC) website.[1] Surveillance and laboratory data for hMPV is not available routinely from all countries.

According to the most recent surveillance data on acute respiratory infections shared by the China CDC with data up to 29 December 2024, there has been an upward trend of common acute respiratory infections, including those due to seasonal influenza viruses, RSV and hMPV – as expected for this time of year during the Northern Hemisphere winter. 

Influenza is currently the most reported cause of respiratory disease, with the highest positivity rate among all monitored pathogens for all age groups except children aged 5-14 years for whom mycoplasma pneumoniae had the highest positivity rate. SARS-CoV-2 activity remains low however with an increase in reported severe COVID-19 cases. 

The predominant circulating SARS-CoV-2 variant in the country is XDV and its sublineages accounting for  59.1% detection among sequenced samples. ILI activity in China’s northern and southern provinces have been increasing since late 2024, following the previous year’s trends. Current ILI activity in the southern provinces remains below that of the previous two years, while current ILI activity in the northern provinces is similar to levels seen at this time in the previous two years.

China’s reported levels of acute respiratory infections, including hMPV, are within the expected range for the winter season with no unusual outbreak patterns reported. Chinese authorities confirmed that the health care system is not overwhelmed, hospital utilization is currently lower than this time last year, and there have been no emergency declarations or responses triggered. Since the expected seasonal increase was observed, health messages have been provided to the public on how to prevent the spread of respiratory infections and reduce the impact of these diseases.

Public health response

Based on the expected increase in respiratory infections during the winter season, countries, including China, have been providing health messages to the public on how to prevent the spread of respiratory infections and reduce the impact of disease.

WHO risk assessment

In temperate climates, seasonal epidemics of common respiratory pathogens, including influenza, occur often during winter periods. The observed increases in acute respiratory infections and associated pathogen detections in many countries in the Northern hemisphere in recent weeks is expected at this time of year and is not unusual. The co-circulation of respiratory pathogens may pose a burden to health facilities. 

WHO advice

WHO recommends that individuals in areas where it is winter take normal precautions to prevent the spread and reduce risks posed by respiratory pathogens, especially to the most vulnerable. People with mild symptoms should stay home to avoid infecting other people and rest. 

People at high risk or with complicated or severe symptoms should seek medical care as soon as possible. 

Individuals should also consider wearing a mask in crowded or poorly ventilated spaces, cover coughs and sneezes with a tissue or bent elbow, practice regular handwashing, and get recommended vaccines as per physician and local public health authorities’ advice.[2]

WHO advises Member States to maintain surveillance for respiratory pathogens through an integrated approach, considering country context, priorities, resources and capacities. WHO has published guidance on integrated surveillance here. WHO has also updated guidance on assessing influenza epidemic and pandemic severity, including the impact on healthcare facilities, here.

Based on the current risk assessment, WHO advises against any travel or trade restrictions related to current trends in acute respiratory infections.

Further information

-- World Health Organization (WHO). Implementing the integrated sentinel surveillance of influenza and other respiratory viruses of epidemic and pandemic potential by the Global Influenza Surveillance and Response System. Available at: https://iris.who.int/handle/10665/379678

-- WHO fact sheet for Influenza (Seasonal): https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal)

-- WHO Routine influenza weekly updates. Available at:https://www.who.int/teams/global-influenza-programme/surveillance-and-monitoring/influenza-updates

-- WHO Influenza surveillance outputs. Available at: https://www.who.int/teams/global-influenza-programme/surveillance-and-monitoring/influenza-surveillance-outputs

-- WHO Global COVID-19 Dashboard. Available at:  https://data.who.int/dashboards/covid19/cases

-- WHO Coronavirus disease (COVID-19) Epidemiological Updates. Available at: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports

-- WHO Clinical practice guidelines for influenza. Available at: https://www.who.int/publications/i/item/9789240097759

-- WHO Respiratory Syncytial Virus (RSV) disease. Available at: https://www.who.int/teams/health-product-policy-and-standards/standards-and-specifications/norms-and-standards/vaccine-standardization/respiratory-syncytial-virus-disease https://www.chinacdc.cn/jksj/jksj04_14249/

-- US CDC Human Metapneumovirus. Available at: https://www.cdc.gov/human-metapneumovirus/about/index.html

-- American Lung Association. Human Metapneumovirus (hMPV) Symptoms and Diagnosis. Available at: https://www.lung.org/lung-health-diseases/lung-disease-lookup/human-metapneumovirus-hmpv/symptoms-diagnosis

[1] China CDC Weekly Influenza Surveillance Report. Available at: https://www.chinacdc.cn/jksj/jksj04_14249/   

[2] WHO Clinical practice guidelines for influenza. Available at: https://www.who.int/publications/i/item/9789240097759

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Source: World Health Organization, https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON550

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#Avian #flu #risk still ‘low’ after first #US #patient dies from #H5N1 virus: #WHO

7 January 2025 

A day after the United States reported its first human death from avian flu, the UN World Health Organization (WHO) insisted on Tuesday that the risk to the wider population remains “low”. 

WHO spokesperson Dr. Margaret Harris told reporters in Geneva that the H5N1 virus causing the disease is “not circulating in humans but jumping into humans” who are exposed to poultry or dairy cattle. “We’re not seeing sustained circulation,” she insisted.

Underlying conditions

The man who died of the disease in Louisiana was over 65 and reportedly had underlying medical conditions, Dr. Harris said. 

According to the health authorities, he had been exposed to chickens and wild birds. Several dozen people in the US have contracted avian influenza – commonly referred to as bird flu – during the current outbreak, mainly farmworkers in close contact with poultry flocks and cattle herds.

Dr. Harris stressed that WHO’s assessment of the risk to the general population “is still low and remains set”. The main concern is for people who work in animal industries because they need to be better protected from infection.

The WHO spokesperson added that the United States was continuing to carry out “a lot of surveillance” in the human and animal population, “in the methods we use for farming, for our food production…all those things need to be combined because indeed it always does pose a risk”.

China respiratory virus is not new

Meanwhile, a respiratory virus gaining ground in China, known as the human metapneumovirus, or hMPV, has been sparking media attention in recent weeks, but it does not represent a new or major threat, Dr. Harris insisted.

The UN health agency spokesperson said that such infections are on the rise in China “as expected during winter”, with seasonal influenza being “by far the most common among them”, as reported by the Chinese Center for Disease Control and Prevention.

“China’s reported levels of respiratory infections are within the usual range for the winter season,” Dr. Harris explained. “Authorities report that hospital utilization is currently lower than this time last year, and there have been no emergency declarations or responses triggered,” she added.

As for hMPV, it was first identified in 2001 and “has been in the human population for a long time”, Dr. Harris clarified. 

‘Very, very low’ risk

She added that it is a common virus that circulates in winter and spring and usually “causes respiratory symptoms similar to the common cold”. 

Like any of the hundreds of common cold viruses known to exist, it can lead to more serious disease in patients with low immunity, particularly but not limited to newborns and the elderly.

Asked about hMPV’s mortality rate, Dr. Harris described it as “very, very low”. It is not a pathogen that normally leads to deaths in humans, save for the most vulnerable, she concluded, recommending “simple” prevention measures, such as wearing a mask, improving ventilation of closed spaces and handwashing.

Source: United Nations, https://news.un.org/en/story/2025/01/1158776

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Social Media #Memes and Early Public #Opinion #Formation Regarding Highly Pathogenic Avian #Influenza (HPAI) as a Public Health #Threat in the #USA

 {Summary}

Misinformation, disinformation, and conspiracy theories gain traction in times of uncertainty when little is known about a disease and when trust in government and public institutions is low. Amidst uncertainty, public health-related memes act as a sort of coping mechanism. Memes images, text, or video that serve as a shorthand form of communication—have the potential to spread quickly and widely on social media. While memes can be humorous, perhaps harmless, they can have serious effects at other times, as during the COVID-19 pandemic. One thing they have in common, however, is their transportability from user to user and platform to platform.  Frame analysis of Internet memes is useful for categorizing what we call frames of meaning in digital space. Unlike the agenda-setting function of mass media, in which gatekeepers (e.g., news editors) set the agenda regarding public issues, framing theory in the digital age is more dynamic, as content may take on different forms or formats, change over time, and the digital frame may traverse media platforms. Consumer-generated content (CGC) plays a significant role in setting the agenda or framing the event. Based onthe fluid nature of social networks and changes in the hierarchy of agenda setting, the model of connective action applied to public discourse on digital media can be visualized and analyzed through topic modeling to understand the role that memes play in shaping emergent public issues. In this study, we focused on memes shared in response to the current Highly Pathogenic Avian Influenza (HPAI), specifically the H5N1 outbreak in the United States, to get a glimpse into the early stages of public opinion formation around a potential public health issue. We present this approach to study the situational awareness of this public health issue through analysis of memes as a form of public discourse and as a cost-effective tool for resource challenged public health agencies to scan the environment for emergent issues.

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Source: Disaster Medicine and Public Health Preparedness, https://www.cambridge.org/core/journals/disaster-medicine-and-public-health-preparedness/article/social-media-memes-and-early-public-opinion-formation-regarding-highly-pathogenic-avian-influenza-hpai-as-a-public-health-threat-in-the-united-states/5119C8A5DA2152D4392FC93BDCE575A8

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#Polymerase #mutations underlie #adaptation of #H5N1 #influenza virus to dairy #cattle and other #mammals.

Abstract

In early 2024, an unprecedented outbreak of H5N1 high pathogenicity avian influenza was detected in dairy cattle in the USA. The epidemic remains uncontrolled, with spillbacks into poultry, wild birds and other mammals including humans. Here, we present molecular and virological evidence that the cattle B3.13 genotype H5N1 viruses rapidly accumulated adaptations in polymerase genes that enabled better replication in bovine cells, as well as cells of other mammalian species including humans and pigs. We find evidence of several mammalian adaptations gained early in the evolution of these viruses in cattle including PB2 M631L, which is found in all cattle sequences, and PA K497R, which is found in the majority. Structurally, PB2 M631L maps to the polymerase-ANP32 interface, an essential host factor for viral genome replication. We show this mutation adapts the virus to co-opt bovine ANP32 proteins and thereby enhances virus replication in bovine and primary human airway cells. Importantly, we show that ongoing evolution during 2024 in the PB2 gene, including a convergently arising D740N substitution, further increases polymerase activity in a range of mammalian cells. Thus, the continued circulation of H5N1 in dairy cattle allows virus adaption improving replicative ability in cattle and increasing zoonotic spillover risk.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.01.06.631435v1?rss=1

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