New Jersey DOH: First Reported H5N1 In Cats

 
Credit Wikipedia

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There are now well over 100 cats confirmed with H5N1 in the United States over the past 12 months, and while most of them have been reported in western states, the recent eastward surge of H5N1 across the nation via migratory birds has put more animals at risk. 

Today we've this report from the New Jersey Department of Health. 

While the headline from the press release, and the opening paragraph, make this sound like only one cat was found infected, as we read further down we learn that other cats on the property are ill - a second (indoor) cat has tested positive - and additional tests are pending. 

H5 Highly Pathogenic Avian Influenza Confirmed in New Jersey Cat 

Caution Advised Though H5N1 Public Health Risk to Humans Remains Low

TRENTON, NJ - The first feline case of H5 Highly Pathogenic Avian Influenza (HPAI or “bird flu”) in New Jersey has been confirmed in a feral cat from Hunterdon County. The case was confirmed by the United States Department of Agriculture (USDA) National Veterinary Services Laboratory, and follows previous national reports of confirmed feline cases in other states.  

The cat developed severe disease, including neurologic signs, and was humanely euthanized. Other cats on the same property were also reported ill, and one additional indoor-outdoor cat was subsequently confirmed positive for H5 HPAI. Other tests are still pending, and the investigation is ongoing.

The overall public health risk remains low at this time. While H5 HPAI has been detected in humans in the U.S. – primarily in individuals with close contact with infected poultry or dairy cattle – there have been no human cases reported in New Jersey, and none of the cases across the country are known to have resulted from exposure to an infected cat.

Local health officials are working closely with the New Jersey Department of Health in conducting follow up and symptom monitoring on individuals that have been in contact with these cats. All exposed individuals are currently asymptomatic. Residents who have had close, unprotected contact with a cat or other animal infected with H5 HPAI should contact their local health department and monitor themselves for symptoms for 10 days following their last exposure.

“While the risk of H5 infection to the general population remains low at this time, it is important for people to learn more about the situation and take steps to avoid potential infection through exposure to animals, including feral cats,” said New Jersey Health Commissioner Kaitlan Baston, MD, MSc, DFASAM. “We continue to work with state and federal partners to monitor the spread of this virus and provide public information on mitigating the risks.”

Cats are particularly susceptible to H5 HPAI and often experience severe disease and high mortality when infected. Potential exposure sources of H5 HPAI for cats include consuming raw (unpasteurized) milk or raw/undercooked meat contaminated with the virus, infected birds or other animals and their environments, or exposure to contaminated clothing or items (fomites) worn or used on affected premises.

The cats tied to this incident in Hunterdon County had no known reported exposures to infected poultry, livestock, or consumption of raw (unpasteurized) milk or meat, but did roam freely outdoors, so exposure to wild birds or other animals is unknown.

Clinical signs in cats can include:

• General signs: Loss of appetite, fever, lethargy
• Respiratory signs: Discharge from the eyes and mouth, sneezing, coughing, difficulty breathing
• Neurologic signs: Seizures, circling, wobbling gait, blindness.

New Jersey residents should contact their veterinarian immediately if they are concerned that their cat may have H5 bird flu. Anyone who suspects a possible exposure or who has H5 HPAI concerns about their cat should contact their veterinarian prior to bringing the cat in to be seen so that the veterinarian can take the necessary precautions to prevent spread of disease. Residents who observe a sick stray or feral cat should contact their local animal control for assistance.

Veterinarians who suspect H5 HPAI in a cat should follow CDC recommendations to help protect themselves and prevent exposures, including wearing personal protective equipment (PPE) when handling the cats. All suspect feline cases should be reported to the New Jersey Department of Health Communicable Disease Service at 609-826-4872 or zoonoticrn@doh.nj.gov. Testing for suspect feline cases is available at the New Jersey Animal Health Diagnostic Laboratory, a member of the USDA’s National Animal Health Laboratory Network. Guidance for veterinarians on specimen collection and submission can be found here.

New Jersey residents can find additional information and recommendations on ways to help prevent H5 bird flu infection in cats from the American Veterinary Medical Association.

Additionally, cat owners can take the following steps to help protect their pets:

• Do not feed cats raw (unpasteurized) milk or dairy products, and avoid feeding any raw or undercooked meat treats or diets.
• Keep cats indoors to prevent exposure to birds and other wildlife.
• Keep cats away from livestock, poultry, and their environments.
• Avoid contact with sick or dead birds and other wildlife yourself.
• Thoroughly wash your hands after handling your cat and after any encounters with poultry, livestock, or wild birds and other animals.
• Change your clothes and shoes, and thoroughly wash any exposed skin, after interacting with sick or dead animals that may harbor the H5N1 virus, and before interacting with your cat.
• Contact a veterinarian if you notice signs of H5 HPAI or think your cat might have been exposed to the virus.

“The H5N1 virus has the ability to move from one species to another,” New Jersey Agriculture Secretary Ed Wengryn said. "That is why we have worked closely with our poultry and dairy industries on biosecurity measures to prevent exposure by wild animals, and feral cats are another example of the risks to livestock and humans.”

“Despite low risk to the public, avian influenza is believed to be present in wild birds in all of New Jersey’s counties,” Environmental Protection Commissioner Shawn M. LaTourette said. “The Department of Environmental Protection continues to work closely with state and federal partners to track and respond to avian flu in wild birds and keep the public informed.” 

NJDOH continues to work in collaboration with the NJ Department of Environmental Protection (NJDEP) and the NJ Department of Agriculture (NJDA) to monitor occurrences of H5N1 Avian Influenza and its impact in the State.

• If you find sick or dead wild birds, do not handle them. Contact the NJDEP’s Fish and Wildlife hotline at 1-877-WARNDEP. 
• To report sick or dead poultry, do not handle them. Contact the NJDA Division of Animal Health at 609-671-6400. 

Although the CDC continues to rank the risk to general public from avian flu as low, they do provide very specific guidance to pet owners on how to limit their risk of infection from the virus (see What Causes Bird Flu in Pets and Other Animals).

WHO Recommendations for Influenza Vaccine Composition for the 2025-2026 Northern Hemisphere Influenza Season

Credit ACIP


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Twice each year international influenza experts meet to discuss recent developments in human and animal influenza viruses around the world, and to decide on the composition of the next influenza season’s flu vaccine. Due to the time it takes to manufacture and distribute a vaccine, decisions on which strains to include must be made six months in advance.

Which means the composition of the northern hemisphere’s vaccine must be decided upon in February of each year, while decisions on the southern hemisphere’ vaccine are made in September.

Today the WHO released their recommendations for the composition of this fall's 2025-2026 Northern Hemisphere flu vaccine, which updates the H3N2 virus for both egg and cell-based vaccines.   First, the press release from the WHO, after which I'll have a bit more. 

Recommendations announced for influenza vaccine composition for the 2025-2026 northern hemisphere influenza season
28 February 2025
News release
Reading time: Less than a minute (229 words)

The World Health Organization (WHO) today announced the recommendations for the viral composition of influenza vaccines for the 2025-2026 influenza season in the northern hemisphere. The announcement was made at an information session at the end of a 4-day meeting on the Composition of Influenza Virus Vaccines, a meeting that is held twice annually.

WHO organizes these consultations with an advisory group of experts gathered from WHO Collaborating Centres and WHO Essential Regulatory Laboratories to analyse influenza virus surveillance data generated by the WHO Global Influenza Surveillance and Response System (GISRS). The recommendations issued are used by the national vaccine regulatory agencies and pharmaceutical companies to develop, produce, and license influenza vaccines for the following influenza season.

The periodic update of viruses contained in influenza vaccines is necessary for the vaccines to be effective due to the constant evolving nature of influenza viruses, including those circulating and infecting humans.

The WHO recommends that trivalent vaccines for use in the 2025-2026 northern hemisphere influenza season contain the following:

Egg-based vaccines

• an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
• an A/Croatia/10136RV/2023 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

Cell culture-, recombinant protein- or nucleic acid-based vaccines

• an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
• an A/District of Columbia/27/2023 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

The recommendation for the B/Yamagata lineage component of quadrivalent influenza vaccines remains unchanged from previous recommendations: a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

 

Normally within a week or two of the release of the WHO vaccine recommendations, the FDA's advisory group ACIP (Advisory Committee on Immunization Practices) meets to recommend the formulation for the U.S. fall flu vaccines.  The three-day ACIP meeting scheduled for late this week has already been postponed (see notice below).

Last night Chris Dall at CIDRAP reported that the upcoming ACIP meeting on the flu vaccine - scheduled for March 13th - has also been cancelled. 

FDA cancels advisory committee meeting on flu vaccine strain selection
Chris Dall, MA
February 27, 2025

An upcoming meeting of a Food and Drug Administration (FDA) vaccine advisory board to select virus strains for next season's flu shot has been canceled.

The March 13 meeting of the FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) was scheduled to make recommendations for the flu strains that will be included in the 2025-26 flu shot or nasal spray for the Northern Hemisphere. VRPBAC typically meets in March to make those recommendations, which are based on what flu strains are expected to be circulating in the fall and winter. The FDA uses the recommendations to direct vaccine manufacturers on the composition of the shots, which take roughly 6 months to produce.

VRBPAC members were alerted that the meeting was canceled in an email from the FDA that did not include an explanation, according to the Washington Post. The cancelation is raising concerns that the timing and availability of next season's flu shot could be affected.

          (Continue  . . . ) 

While a delay of a few weeks - or even a month or more - might not be enough to disrupt vaccine deliveries this fall, there isn't a lot of slack in the timetable.  And the manufacturing of (mostly egg-based) vaccines can sometimes face unexpected delays, particularly when a new strain is introduced. 

While the numbers vary from year-to-year, 6 weeks ago the :

CDC estimates that during the 2023-2024 season, flu vaccination prevented 9.8 million flu-related illnesses, 4.8 million medical visits, 120,000 hospitalizations, and 7,900 deaths.

And that was during a much less-severe flu season that we are seeing this year.  Add in the potential for increased H5N1 activity in the months ahead, and reducing seasonal flu - and potential reassortment opportunities - should be a priority. 

Whether that translates into action, remains to be seen. 

Virology Mini-Review: Pandemic Risk Stemming From the Bovine H5N1 Outbreak: An account of the Knowns and Unknowns

 

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While the jury remains out on whether an avian H5 influenza can spark a human pandemic (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?), we continue to see an increasing number of worrisome spillovers into scores of mammalian species, including dairy cattle. 

Human infections have risen over the past year to levels not seen in nearly a decade, and globally, we are dealing with a great many more H5Nx variants (subclades, subtypes & genotypes) than ever before.

Even if there is a species barrier that prevents an H5 virus from sparking a pandemic, twice in my lifetime (1957 & 1968) we've seen an avian virus reassort with human seasonal influenza to produce a pandemic strain (see Preprint: Intelligent Prediction & Biological Validation of the High Reassortment Potential of Avian H5N1 and Human H3N2 Influenza Viruses).

An H3 or an H1 virus with internal genes loaned from H5N1 could be both highly transmissible and virulent in humans.  One need look no further than the infamous `Liverpool flu' of 1951 (see When Seasonal Influenza Goes Rogue) for evidence of the impact of a `mutated' seasonal flu virus. 

While its been nearly a year since we first learned of H5N1's (genotype B3.13) spillover into cattle - which conservatively has spread to nearly 1,000 herds across 16 states - there are still a great many unknowns.  

Complicating matters, a month ago, we learned that a second - potentially more dangerous genotype (D1.1) - has also infected herds in at least two states. 

Despite these warning signs, the dairy industry and many agencies continue to treat H5N1 in cattle (and in poultry) as more of an economic problem than a public health threat. We've seen resistance on the part of farm workers, and their employers, to testing for the virus (in people & in livestock), and there remain a great many unknowns surrounding source, transmission, and threat of this virus in dairy cattle. 

Yesterday the Journal Virology published an excellent mini-review by the  The Risk Assessment Pipeline working group of the NIAID Centers of Excellence for Influenza Research and Response (CEIRR) Network, which looks at what we know - and what we don't know - about the pandemic risks posed by H5N1 in cattle. 

This is a lengthy, and well-written review and I highly recommend that you read it in its entirety.  While cattle-centric, it touches on other aspects, including spillover into cats, pigs, humans, and other species.  

As sobering as all of this is, the long list of barriers to research should give us all pause. 

I've only posted a miniscule portion of the review below, so follow the link, and plan to spend some time reading it.  I'll have a brief postscript after the break. 

Pandemic risk stemming from the bovine H5N1 outbreak: an account of the knowns and unknowns

Authors: Anice C. Lowen, Amy L. Baker, Andrew S. Bowman , Adolfo García-Sastre , Scott E. Hensley , Seema S. Lakdawala , Louise H. Moncla, Show All (16 Authors) , The Risk Assessment Pipeline working group of the NIAID Centers of Excellence for Influenza Research and Response (CEIRR) NetworkAuthors Info & Affiliations

https://doi.org/10.1128/jvi.00052-25

PDF/EPUB

ABSTRACT

H5N1 subtype influenza A viruses represent a long-standing pandemic concern. Owing to their global occurrence in poultry, humans are routinely exposed to these viruses, and hundreds of human cases have been documented worldwide since 2003. The relevant viral lineages are not static, however, and have recently undergone a massive expansion of host range and geographic distribution. Within this expansion, the introduction of H5N1 viruses into dairy cattle in the United States has spawned a novel animal-human interface. In esponse, public health agencies have sought to evaluate the risk of an H5N1 pandemic stemming from the bovine outbreak. These assessments draw on evidence from the field and the laboratory to score a series of recognized risk factors. As such, their utility hinges on fundamental understanding of the processes that drive pandemic emergence and the availability of relevant data. Advancing this understanding and gathering data prior to and during an outbreak are primary missions of the NIAID Centers of Excellence for Influenza Research and Response (CEIRR) Network. To further these goals and highlight the need for an invigorated response across US agencies, here, we review gaps in understanding of the dairy cattle outbreak and identify constraints on efforts to close these gaps.

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CONCLUSION

Meaningful assessment and effective mitigation of pandemic risk depend on a thorough understanding of the drivers of viral emergence and spread across animal and human populations. Both rapid outbreak-response and sustained research are needed to furnish the information required. At present, a deepening of the research response to the ongoing H5N1 panzootic will help to define the scope of the outbreak and the nature of human exposure. The knowledge gained will enable the design of biosecurity measures to diminish H5N1 circulation in animals, thereby reducing human exposure. Now and over the long term, research is needed to better define the factors that allow influenza pandemics to occur. While certain features are well-defined, uncertainty remains as to whether a given zoonotic threat can trigger a pandemic. Such research will enable more accurate assessment of risk, in turn allowing targeted preparation of antivirals, vaccines, and other interventions that can reduce the impact of an outbreak.

         (Continue . . . )

Thirty years ago anthropologist and researcher George Armelagos of Emory University posited that since the mid-1970s the world has entered into an age of newly emerging infectious diseases, re-emerging diseases and a rise in antimicrobial resistant pathogens (see The Third Epidemiological Transition (Revisited). 

Emerging infectious diseases have become such an important public health threat that the CDC maintains as special division – NCEZID (National Center for Emerging and Zoonotic Infectious Diseases) – to deal with them, and in the 1990s the CDC established the EID Journal dedicated to research on emerging infectious diseases.

Recent studies suggest that the frequency, and impact, of pandemics are only expected to increase over the next few decades.

BMJ Global: Historical Trends Demonstrate a Pattern of Increasingly Frequent & Severe Zoonotic Spillover Events

PNAS Research: Intensity and Frequency of Extreme Novel Epidemics

And yet, at this critical juncture in history, we are dismantling our disease surveillance, investigative, and reporting systems (see Flying Blind In The Viral Storm). Many nations - including our own - have chosen to ignore the IHR 2005 regulations and stop (or severely limit) reporting to the WHO and WOAH on outbreaks (see From Here To Impunity).

While I can't tell you if H5Nx will spark the next pandemic, something will.  

Probably a novel flu virus, but there are plenty of other contenders; coronaviruses, henipaviruses, bunyaviruses . . . or maybe something out of left field.

Abandoning basic science, research, and disease mitigation tools - like vaccines and face masks -  may help fulfill some populist agenda - or produce some temporary economic gain - but it will ultimately result in needless deaths and suffering. 

But at least our leaders can honestly say when the next pandemic does arrive: 

They never saw it coming . . . 

WHO AFRO: DRC Investigation on Cluster of Illness and Community Deaths in Equateur Province

 

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Over the past 3 months we've seen several reports of a `mystery' outbreak in the DRC (see WHO DON: Undiagnosed disease - Democratic Republic of the Congo), and while that first outbreak was eventually attributed to a combination of severe Malaria and malnutrition, there have been more recent, similar outbreaks reported in the DRC. 

The latest report comes from Equateur province, and while both Ebola and Marburg have been ruled out - and roughly half of the cases tested were positive for malaria -  the cause of this outbreak remains unknown. 

While most `mystery' outbreaks turn out to be due to something already known (malnutrition, measles, malaria, meningitis, contaminated food or water, etc.), every once in a while something more exotic is at work. 

This report from the WHO, describes what is currently known about the situation. 

Democratic Republic of the Congo deepens investigation on cluster of illness and community deaths in Equateur province

27 February 2025

Kinshasa – Health authorities in the Democratic Republic of the Congo and experts from World Health Organization (WHO) are carrying out further investigations to determine the cause of another cluster of illness and community deaths in Equateur province. In recent months, disease surveillance has identified increases in illness and deaths three times in different areas of the country, and triggered follow-up investigations to confirm the cause and provide needed support.

Since the beginning of 2025, a series of illnesses and community deaths have affected Equateur province. The most recent cluster occurred in the Basankusu health zone, where last week 141 additional people fell ill, with no deaths reported. In the same health zone, 158 cases and 58 deaths were reported in the same health zone earlier in February. In January, Bolamba health zone reported 12 people who fell ill including 8 deaths.

Increased disease surveillance has identified in total of 1096 sick people and 60 deaths in Basankusu and Bolomba fitting a broad case definition that includes fever, headache, chills, sweating, stiff neck, muscle aches, multiple joint pain and body aches, a runny or bleeding from nose, cough, vomiting and diarrhoea.

The Democratic Republic of the Congo is facing many concurrent crises and outbreaks, putting a further strain on the health sector and the population.

In response to the latest cluster of illness, a national rapid response team from Kinshasa and Equateur including WHO health emergency experts was deployed to Basankusu and Bolomba health zones to investigate the situation and determine if there is an unusual pattern. The experts are stepping up disease surveillance, conducting interviews with community members to understand the background, and providing treatment for diseases such as malaria, typhoid fever and meningitis.

WHO has delivered emergency medical supplies, including testing kits, and developed detailed protocols to enhance disease investigation.

Initial laboratory analysis has turned out negative for Ebola virus disease and Marburg virus disease. Around half of the samples tested positive for malaria, which is common in the region. Further tests are to be carried out for meningitis. Food, water and environmental samples will also be analysed, to determine if there might be contamination. The various samples will be sent for further testing at the national reference laboratory in Kinshasa. Earlier samples turned out not to be viable and re-testing was undertaken.

Basankusu and Bolomba are about 180 kilometres apart and more than 300 kilometres from the provincial capital Mbandaka. The two localities are reachable by road or via the Congo River from Mbandaka. This remoteness limits access to health care, including testing and treatment. Poor road and telecommunication infrastructure are also major challenges.

WHO is supporting the local health authorities reinforce investigation and response measures, with more than 80 community health workers trained to detect and report cases and deaths.

Further efforts are needed to reinforce testing, early case detection and reporting, for the current event but also for future incidents. WHO remains on the ground supporting health worker, collaborating closely with zonal, provincial and national health authorities to provide lifesaving medical supplies and to coordinate response to curb the spread of the illness and other outbreaks in the region.

OFFLU Statement on the Development of a Global Consensus H5 Influenza Genotyping Framework

 

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With 18 HA (hemagglutinin) types and 11 different NA (neuraminidase) types there are nearly 200 possible influenza subtypes (e.g. H1N1, H5N1, H7N8, etc.). To date, more than 130 have already been detected in nature. 

Each subtype (based on the combination of HA and NA genes) is further classified by its HA clade (e.g. 2.3.4.4), and within each clade there can be multiple subclades (e.g. 2.3.4.4b, 2.3.2.1.c , etc.). This alone can yield thousands of variations.

(Credit CDC)

As a segmented virus with 8 largely interchangeable parts, the flu virus is like a viral LEGO (TM) set which allows for the creation of  a vast number of unique variants.  Each of these reassortments is designated by its genotype (e.g. B3.13, D1.1, A2, etc.). 

In North America alone, more than 100 genotypes have been identified over the past 3 years, with new ones destined to emerge over time. Globally, that number is much larger, although given the limits of surveillance and reporting, we aren't aware of all of them. 

While the nomenclature for subtypes and clades have been standardized around the globe - different regions of the world have developed their own genotype classification system - making it difficult to compare studies or share data from Asia, and Europe, and North America. 

Yesterday OFFLU - the WOAH/FAO joint network of expertise on avian influenza - released a statement proposing the creation of a cross-reference document this year, to be followed by `. . .  a position paper that highlights the importance of a harmonized framework for addressing gaps in tracking, communication, and response to the evolving challenges posed by H5 viruses.'.

First the OFFLU statement, after which I'll have a brief postscript.

OFFLU Statement on the Development of a Global Consensus H5 Influenza Genotyping Framework

Since its inception in 2005, OFFLU (the WOAH-FAO network of expertise on animal influenza) has been closely monitoring the global impacts of avian influenza, including working with multiple countries and stakeholders affected by the current H5N1 HPAI panzootic. Field veterinarians and OFFLU scientists in FAO and WOAH designated influenza Reference Centres play a key role in responding to novel outbreaks and characterizing avian influenza (AI) viruses.

OFFLU is committed to ensuring effective stakeholder communication around animal influenzas. The World Organization of Health (WHO)/OFFLU H5 Evolution Working Group proposed a unified nomenclature1 specifically for high pathogenicity avian influenza (HPAI) H5 viruses of the goose/Guangdong lineage based upon the hemagglutinin gene only, which remains under continued revision. This nomenclature has successfully enabled the use of a universal, commonly understood system around the world by multiple stakeholders.

However, while viral genome sequences are increasingly available from diverse regions and hosts, the absence of a globally harmonized nomenclature for influenza A(H5) genotypes - particularly for highly pathogenic H5 goose/Guangdong viruses - poses a significant challenge to communication between animal and public health partners within and beyond the OFFLU network. In this context, genotypes are defined as viruses with a unique eight-gene segment composition resulting from reassortment events. 

The current use of multiple genotyping systems impedes the tracking of genetic changes, hinders the identification of emerging strains, and complicates the assessment of virus spread and potential risks to animal and public health. To address this critical gap, OFFLU, in collaboration with global partners, is spearheading the development of a universal H5 influenza genotyping framework, beginning with the H5 goose/Guangdong lineage viruses, starting with clade 2.3.4.4b.

The Need for a Global Harmonized Genotyping Framework

Several tools and systems have been developed to classify and genotype animal influenza viruses, playing a crucial role in regional and local communication about avian influenza spread. While these approaches have significantly advanced the tracking and analysis of virus evolution, they remain continent or region-specific and lack global alignment. Given the unprecedented spread of avian influenza across geographic regions, there is a pressing need for a unified, widely accessible framework that builds on the strengths of existing systems to facilitate global communication. Importantly, this universal system will not replace regional systems but will serve as a means of global harmonization, ensuring interoperability without disrupting established practices. Such a framework would facilitate cross-border risk comparisons, enable efficient genotype tracing, and allow better communication regarding assessment of H5 wholegenome constellations, including the public health risk. Although creating and maintaining this framework presents significant challenges, it is a crucial step toward effectively confronting the evolving threats posed by avian influenza viruses.

OFFLU Approach

To develop the proposed genotyping framework, OFFLU Avian Influenza Technical Activity will first create a reference document, identifying and cross-referencing genotypes amongst existing classification systems from all continents, providing a foundation for standardization. This will be followed by a position paper that highlights the importance of a harmonized framework for addressing gaps in tracking, communication, and response to the evolving challenges posed by H5 viruses.

A technical team will develop a comprehensive genotyping framework to define all H5 goose/Guangdong lineage genotypes circulating globally, starting with HA clade 2.3.4.4b, and provide a nominal tool for cross-referencing genotypes across existing classification schemes from all continents. This framework will include a system for effectively communicating the significance of each genotype to decision-makers, ensuring clarity and avoiding misattribution or implications of country-specific origins. To promote inclusivity and relevance throughout this process, global experts and stakeholders in existing genotyping systems will be engaged and invited to contribute.

We plan to conduct initial testing of the framework and associated tools with global experts in late June 2025. We will then expand dissemination of the framework to scientists, policymakers, public health officials, and other stakeholders, emphasizing that the new genotype nomenclature is not an indicator of emerging variants but rather a universal naming system for improved communication. The framework will be publicly accessible, ensuring transparency and ease of use across regions and disciplines.

OFFLU (www.offlu.org) will continue to support the activities of its parent organisations (FAO and WOAH) and partners (WHO) in ensuring that scientifically sound information is available on strains of virus that are detected in animals.

Disclaimer: This statement provides the point of view of independent OFFLU experts and does not necessarily reflect the position of the parent organisations FAO and WOAH.

References

1 World Health Organization/World Organisation for Animal Health/Food and Agriculture Organization (WHO/OIE/FAO) H5N1 Evolution Working Group. Revised and updated nomenclature for highly pathogenic avian influenza A (H5N1) viruses. Influenza Other Respir Viruses. 2014 May;8(3):384-8. doi: 10.1111/irv.12230. Epub 2014 Jan 31. PMID: 24483237; PMCID: PMC4181488.

While there have been multiple genotypes of H5Nx going back decades - over the past 3 years, with the rapid global expansion of the virus - we've seen an unprecedented explosion in its diversity.  Since different genotypes can possess different traits (transmissibility, host range, virulence, etc.), keeping track of them has become crucial. 

The recently emerged H5N1 D1.1 genotype, for example, appears to produce more serious illness in humans than the `bovine' B3.13 genotype, while H5N6 viruses with recombinant internal genes derived from H9N2 have shown increased pathogenicity and transmissibility

Since this framework is to be geared to the HPAI H5 goose/Guangdong lineage of viruses (starting with clade clade 2.3.4.4b), it will also be useful for classifying other H5 subtypes, like H5N6, H5N5, and H5N8.

This is a big job, however, and it won't happen overnight.  But is seems unlikely that HPAI H5 will be going away anytime soon. 

UKHSA Warns Of Potential `Second Wave' Of Norovirus

 

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Noroviruses, which are often mistakenly called `stomach flu’, are single-stranded RNA viruses that are both highly contagious and are able to evolve rapidly. New strains tend to emerge every 4 or 5 years 

Victims usually experience nausea, frequent vomiting & diarrhea, and stomach pain – and may also suffer from headache, fever, and body aches. 

The illness generally runs its course over 1 to 3 (very long) days, and most people fully recover.  But among those who are aged or infirmed, the virus can take a heavy toll.

 According to the CDC, in the United States each year the norovirus produces:

The `standard’ mode of norovirus transmission is considered to be the fecal-oral route, but limited airborne transmission is suspected as well. Complicating matters, alcohol based hand sanitizers are ineffective against this virus.

In 2015, in CID Study: Airborne Norovirus In Healthcare Facilities, a study looked for - and found - norovirus in ambient air samples taken from 8 hospitals, both inside and outside of an infected patient’s room.

While the act of vomiting (see Vomiting Larry And His Aerosolized Norovirus) could account for this airborne infusion of the virus, the usual receptacle is a toilet, followed by a power flush (see Nature: Another Toilet Plume Study To Consider) which may also help disperse the virus through the air. 

While norovirus infections can occur anytime, they tend to be most common between November and April, and can increase the impact of an already busy winter cold/flu/COVID season. 

 This year, the UK has reported an unusually harsh noro season, and in recent weeks the dominant strain (GII.17) has begun to give way to an older variant (G11.4), raising concerns over a ` second wave'.

UKHSA warns of potential second norovirus wave

People who have already had the virus this winter could be at risk again, as new data shows shift in circulating strains.

From: UK Health Security Agency Published 27 February 2025




The latest UK Health Security Agency (UKHSA) data shows norovirus cases continue to rise across the country, with laboratory reports at the highest levels since reporting data this way began in 2014.

Laboratory confirmed cases in the 2 weeks from 3 to 16 February 2025 were 29.4% higher than the previous fortnight and more than double the 5-season average (168.0%) for the same 2-week period. The impact is particularly severe in hospitals and care homes, with cases highest among people aged 65 and over. Cases usually start to decline around this time of year as the weather gets warmer, but it is too soon to conclude whether or not norovirus has peaked this season.

The increased activity this season is associated with the recently emerged GII.17 genotype. However, the latest data shows that a different, but commonly seen genotype (GII.4) is now increasing. Prior to the emergence of GII.17, GII.4 is the genotype that most commonly detected and increased each winter. While the GII.17 genotype remains dominant, accounting for 59% of cases, its prevalence has dropped from 76% since November. Meanwhile, the GII.4 strain has sharply risen, now representing 29% of cases compared to just 10% three months ago.

This means that people who have already had norovirus this season may catch it again, as having one genotype does not fully protect against the other. However, at present there is no indication that either GII.17 or GII.4 leads to more severe illness.

Common symptoms of norovirus include:

• nausea and vomiting
• diarrhoea
• high temperature
• abdominal pain
• aching limbs

Some people, particularly young children, older adults and those with weakened immune systems are more likely to develop severe symptoms, which can cause dehydration. Anyone with these symptoms should drink plenty of fluids.

Amy Douglas, Lead Epidemiologist at UKHSA, said:

Norovirus levels are still exceptionally high and now with multiple genotypes spreading at the same time, people could end up getting infected more than once this season.

We are seeing the biggest impacts in health and social care settings, such as hospitals and care homes. Symptoms of norovirus can be more severe in older adults, young children and those who are immunocompromised. If you have diarrhoea and vomiting, please do not visit hospitals and care homes or return to work, school or nursery until 48 hours after your symptoms have stopped. And don’t prepare food for others, as you can still pass on the virus during this time.

Alcohol gels do not kill norovirus. Wash your hands with soapy warm water and clean surfaces with bleach-based products where possible to help stop infections from spreading.

While it is likely the GII.17 genotype has driven up norovirus cases this season due to a lack of previous immunity, the higher numbers we are seeing may also reflect UKHSA’s improved testing capabilities and changing patterns of infection since the COVID-19 pandemic. Norovirus also spreads more easily in lower temperatures as people spend more time indoors and typically peaks during winter months.

UKHSA experts estimate that reported cases represent only a small fraction of actual infections. For every case reported to national surveillance, approximately 288 cases occur in the community, suggesting around 3 million cases annually in the UK.

Washington State (WSDA) Announces 2 Households with H5N1 Infected Cats Linked to Raw Food

 
Recalled Commercial Cat Food

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Two weeks ago, in Oregon Dept. of Agriculture Statement On H5N1 In Domestic Cats - WSDA Health Alert on Raw Pet Food, we looked at a report on two Oregon Households with H5N1 infected cats, once again linked to raw commercial cat food (manufactured in Washington State).

Yesterday, we saw 6 more cats from Oregon added to the USDA's list, suggesting that outbreak may still be growing. Cats (and dogs), however, can be infected via other exposures (see California: San Mateo County Warns Residents After Stray Cat Found With H5N1).  

Late yesterday the Washington State Department of Agriculture (WSDA) announced the detection of H5N1 in domestic cats from two households (in King & Snohomish counties), both linked to this same brand of of raw commercial cat food. 

One cat has been euthanized, while the other is still receiving treatment.  

While almost certainly an undercount, over the past year we've seen more than 100 domestic cats, and more than 5 dozen larger wild or captive cats, infected with H5N1 in the United States alone.

So far we've seen no evidence of human infection from these infected cats or food products, but the potential exists, and so human contacts are monitored for 10 days after their last exposure. 

The WSDA statement follows. I'll have a bit more after the break.

Washington cats confirmed with HPAI as investigation into contaminated pet food continues

OLYMPIA – The Washington State Department of Agriculture (WSDA) is alerting pet owners that at least two domestic, indoor cats in King and Snohomish counties in Washington have become infected with Highly Pathogenic Avian Influenza (HPAI), with more cats being tested.

Pet owners reported feeding their cats potentially contaminated Wild Coast Raw pet food (previously identified in a prior public health alert). One of the cats was euthanized due to the severity of the illness. The second cat is being treated by a veterinarian.

The Washington Animal Disease Diagnostic Laboratory (WADDL) reported the presumptive positive results of both cats with HPAI on Monday morning, Feb. 24. WSDA received confirmatory results from the National Veterinary Services Laboratory (NVSL) Tuesday, Feb. 25.

The contaminated pet food has been linked to severe illness in cats in Oregon in addition to the reports in Washington mentioned here. For more information and specific lot numbers, visit the Washington State Department of Agriculture recalls and health alerts webpage.

Common clinical signs of HPAI in felines include lethargy, low appetite, fever, hypothermia, progression of illness to pneumonia, progression of illness to neurologic abnormalities and upper respiratory infection. If your pet has consumed this product and has any of these symptoms, please contact your veterinarian immediately. Inform the veterinary clinic before arriving so the veterinary team can prepare to handle the cat in a manner that reduces risk of transmission to veterinary staff, other clients, and other animals.

To date, there have been no documented human cases of HPAI following exposure to an infected cat or contaminated raw pet food products. The currently circulating strain of HPAI is considered low risk to the public, but there is greater risk for those who handle contaminated raw pet food products or who care for infected animals.

People can become infected if the virus enters their eyes, nose, or mouth — such as by handling contaminated pet food or touching contaminated surfaces, especially without thoroughly washing their hands afterward.

Sick animals could be isolated to prevent the possible spread to other animals and people in the home. Caretakers should wear a well-fitting face mask and practice good hand hygiene when caring for infected animals.

Public health monitors all people exposed to animals infected with HPAI through 10 days following their last exposure.

“This is a difficult situation, we love our pets, and it’s devastating when they fall ill,” WSDA field veterinarian Dr. Zac Turner said. “If your cat is showing symptoms, consult a veterinarian as soon as possible.”

The WSDA is continuing to investigate and monitor the situation and urges veterinarians and pet owners to report any additional illnesses potentially linked to the contaminated product. Currently, WSDA does not recommend feeding raw pet food or raw milk to animals.

Six weeks ago - after a spate of similar reports from California, Oregon and Washington - the US FDA Issued New Requirements For Pet Food Manufacturers, although it left the corrective steps largely up to the manufacturers (see snippet below).

Under the PCAF requirements, animal food businesses must conduct a reanalysis of their food safety plan when the FDA determines it is necessary to respond to new hazards and developments in scientific understanding. 

The FDA has determined that it is necessary for cat and dog food manufacturers covered by the PCAF rule, who are using uncooked or unpasteurized materials derived from poultry or cattle (e.g., uncooked meat, unpasteurized milk, unpasteurized eggs) in cat or dog food, to reanalyze their food safety plans to include H5N1 as a new known or reasonably foreseeable hazard. 

How long that analysis will take - and how effective any industry actions will be - remains to be seen. 

CDC: Epidemiological & Laboratory Update On 3 Recent H5N1 Cases

 
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For the first time since January 17th, the CDC has published a Bird Flu Response Update (dated February 26, 2025) which provides details on three recent human H5N1 infections; 1 mild case (Nevada) linked to dairy cattle, and two severe cases (Ohio & Wyoming) linked to poultry exposure. 

All three are reported to be the D1.1 genotype, which emerged last fall in migratory birds, that we now know has a new NA gene, picked up from North American birds (see Emerg. Microbes & Inf: Oseltamivir Resistant H5N1 (Genotype D1.1) found On 8 Canadian Poultry Farms).

Unlike the older B3.13 genotype - which is primarily seen in cattle - this D1.1 genotype appears capable of producing more severe disease. Whether this is due to sporadic mammalian adaptations (D701N, E627K, H275Y, etc.), or to this newly acquired NA gene (or both) isn't clear. 

This CDC update provides partial laboratory analysis on the Nevada and Wyoming cases - both of which sported significant mammalian adaptations (D701N & E627K) -  while sequencing on the Ohio case is still awaited.  

The full update follows:

CDC A(H5N1) Bird Flu Response Update February 26, 2025

At a glance

CDC provides an update on recent developments in the multistate outbreak of avian influenza A(H5N1) virus, or "H5N1 bird flu," in dairy cows, poultry, and other animals in the United States.

What to Know

In this spotlight, CDC provides an update on recent human infections associated with the ongoing U.S. H5N1 bird flu outbreak in animals. These updates include information on the specific animal exposures and the genetic sequence analysis of the viruses detected from three recently confirmed cases in Nevada, Ohio, and Wyoming.

Situation Update

February 26, 2025 – CDC continues to respond to the public health challenge posed by a multistate outbreak of avian influenza A(H5N1) virus, or "H5N1 bird flu," in dairy cows, poultry, and other animals in the United States. CDC is working in collaboration with the U.S. Department of Agriculture (USDA), the Food and Drug Administration (FDA), Administration for Strategic Preparedness and Response (ASPR), state public health and animal health officials, and other partners using a One Health approach.

Public risk remains low

Since April 2024, working with state public health departments, CDC has confirmed H5 bird flu in 70 people in the United States. To date, person-to-person spread of H5 bird flu has not been identified. CDC believes the immediate risk to the general public from H5 bird flu remains low but this risk assessment could change as influenza viruses constantly change. CDC is taking actions to be ready in case the current risk for the public changes.

People with dairy cow or poultry exposures remain at greater risk of infection

People with job- or recreation-related exposures to infected animals are at increased risk of infection. Most (67 of 70) confirmed human infections in the United States have had exposure to infected or presumed to be infected dairy cows or poultry (the source of exposure could not be determined for three cases).

Epidemiology Updates

As of February 24, CDC has confirmed three human cases of H5 bird flu in people who became ill in 2025: a dairy worker with exposure to infected dairy cows (Nevada), a poultry worker with exposure to infected commercial poultry (Ohio), and the owner of an infected backyard poultry flock (Wyoming). These are all considered higher-risk exposures. While the dairy worker was not hospitalized, both people with poultry exposures experienced severe illness and were hospitalized. Both hospitalized cases were confirmed positive from lower respiratory specimens, including a bronchoalveolar lavage and sputum. To date, there has been no evidence of onward spread from any of these people to anyone else.

The dairy worker in Nevada had conjunctivitis (eye redness and irritation) and has recovered. Most infections associated with U.S. dairy cows to date have involved mild respiratory symptoms or conjunctivitis. This person was exposed to infected dairy cows and tested positive for avian influenza A(H5N1) virus.

The poultry worker in Ohio had respiratory symptoms and is home and recovering. This person participated in culling activities on a farm with infected poultry. The initial upper respiratory specimens could not be confirmed as positive for avian influenza A(H5) virus at CDC, so CDC initially reported this as a probable case; a subsequent specimen from the person was confirmed positive for avian influenza A(H5) virus at CDC.

The backyard flock owner in Wyoming had respiratory symptoms and is reported to have underlying health conditions that can make people more vulnerable to severe influenza illness. This person has been discharged from the hospital and is recovering. This person had direct contact with poultry infected with avian influenza A(H5) virus that died on their property. Initial upper respiratory specimens were negative for influenza viruses; a lower respiratory specimen collected several days later in the hospital was positive for avian influenza A(H5N1) virus.

Laboratory Updates

CDC has successfully sequenced the viruses from the Nevada and Wyoming cases. Genetic data have been posted in GISAID (Wyoming: EPI_ISL_19749443, Nevada: EPI_ISL_19726293) and GenBank. Sequencing data are not yet available for the Ohio case.

CDC's analysis of the genetic sequence of the virus isolated from the patient in Nevada identified the virus as an avian influenza A(H5N1) virus from clade 2.3.4.4.b (genotype D1.1). The nucleotide sequence was nearly identical to that of the viruses that USDA reported from dairy cows in Nevada that the person worked with. The virus had a genetic mutation in its polymerase basic 2 (PB2) protein that has previously been associated with more efficient virus replication in mammalian cells (i.e., change of PB2 D701N). This change was previously identified in a human case in Chile in 2023. No other changes associated with mammalian adaption were identified in the sequence data. CDC also did not identify any changes that might impact effectiveness of influenza antiviral medications or existing clade 2.3.4.4b H5 candidate vaccine viruses.

CDC's analysis of the genetic sequence of the virus from the patient in Wyoming identified an avian influenza A(H5N1) virus from clade 2.3.4.4.b (genotype D1.1). The virus had a genetic mutation in its PB2 protein that has previously been associated with more efficient virus replication in people and other mammals (i.e., change of PB2 E627K). This change was previously identified in a human case in Texas during 2024. No other changes associated with mammalian adaption were identified in the sequence data. CDC also did not identify any changes in the sequence data that might impact effectiveness of influenza antiviral medications or existing H5 candidate vaccine viruses. Virus was isolated from the case and will undergo further testing and analysis.

CDC Recommendations

Risk for serious illness highlights importance of prevention

Historically, avian influenza A viruses have caused illnesses ranging from mild to deadly. Most human infections with avian influenza A viruses in the United States since 2024 have been mild. However, serious illnesses have occurred, and one person has died. Because these viruses can cause serious illness and death, it is important for people with exposure to infected or potentially infected animals to take care to follow recommended steps to help protect their health.

The best way to prevent H5N1 bird flu is to avoid sources of exposure whenever possible. For people who must have direct or close contact with infected or potentially infected animals, help limit exposure to avian influenza A(H5) viruses using CDC recommendations for

Everyone
Workers and Employers
Backyard flock owners

Texas DHHS Announces First Death From Measles Outbreak

Credit CDC

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Earlier today, in L.A. County Public Health Confirms Measles Case, we looked at the recent imported case in Los Angeles, the ongoing outbreak in Texas, and discussed how serious measles infection can be; particularly in children.

Sadly, today we have further evidence of the harm from this disease with the following announcement from the Texas DHHS on a school-aged child's death from the virus. 

I'll have a postscript after the break. 

Texas announces first death in measles outbreak

News Release
February 26, 2025


The Texas Department of State Health Services is reporting the first death from measles in the ongoing outbreak in the South Plains and Panhandle regions. The school-aged child who was not vaccinated was hospitalized in Lubbock last week and tested positive for measles.

As of Feb. 25, 124 cases of measles have been confirmed in the outbreak since late January. Most of the cases are in children. Eighteen people have been hospitalized over the course of the outbreak.

Measles is a highly contagious respiratory illness, which can cause life-threatening illness to anyone who is not protected against the virus. During a measles outbreak, about one in five people who get sick will need hospital care and one in 20 will develop pneumonia. Rarely, measles can lead to swelling of the brain and death. It can also cause pregnancy complications, such as premature birth and babies with low birth weight.

Measles can be transmitted by direct contact with infectious droplets or by airborne spread when an infected person breathes, coughs, or sneezes. People who are infected will begin to have symptoms within a week or two after being exposed. Early symptoms include high fever, cough, runny nose, and red, watery eyes. A few days later, the telltale rash breaks out as flat, red spots on the face and then spreads down the neck and trunk to the rest of the body. A person is contagious about four days before the rash appears to four days after. People who could have measles should stay home during that period.

People who think they have measles or may have been exposed to measles should isolate themselves and call their health care provider before arriving to be tested. It is important to let the provider know that the patient may have measles and to get instructions on how to come to the office for diagnosis without exposing other people to the virus.

The best way to prevent getting sick is to be immunized with two doses of a measles-containing vaccine, which is primarily administered as the combination measles-mumps-rubella or MMR vaccine. Two doses of the MMR vaccine prevent more than 97 percent of measles infections. A small number of vaccinated people can occasionally develop measles. In these cases, the symptoms are generally milder, and they are less likely to spread the disease to other people. DSHS and the Centers for Disease Control and Prevention recommend children receive one dose of MMR at 12 to 15 months of age and another at 4 to 6 years. Children too young to be vaccinated are more likely to have severe complications if they get infected with the measles virus. However, each MMR dose lowers the risk of infection and the severity of illness if infected.

Health care providers can find recommendations for infection control and diagnostic testing in DSHS health alerts. Providers should report any suspected cases to their local health department immediately, preferably while the patient is still with the provider.

DSHS posts additional information about the outbreak cases on the News & Alerts page on Tuesdays and Fridays.

During the course of the 1950s – before the introduction of the measles vaccine – measles infected roughly 4 million Americans, hospitalized nearly 50,000, and contributed to the deaths of several hundred every year.

 The chart below (source: CDC) shows the remarkable effectiveness of the vaccination campaign.

 

The WHO reports that the number of measles related deaths have fallen 80% over the past 25 years - and that vaccines have prevented 60 million related deaths.  But even so, more than 100,000 people die from the infection every year, and many more suffer long-term sequelae. 

While not the scourge that is was during most of the 20th century, measles remains a serious public health threat in much of the world, and is only held at bay in developed countries by relatively high vaccination rates.

 A barrier that can be easily overcome if vaccination rates continue to fall. 

USDA Adds 10 More Domestic Cats To H5N1 List

 

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Over the past 2 weeks we've seen two reports from the  Oregon Department of Agriculture (ODA) (see here, and here) on the H5N1 infections and deaths of 3 cats linked to eating raw commercial cat food. 

The Oregon H5N1 dashboard - (see screenshot as of 10 am EST today) - lists only 6 cats infected in the state, and only one of those from Clackamas county.  

But today the USDA updated their H5N1 listing, which adds 6 more cats from Clackamas County, along with 4 other cats from California, Kansas, New Mexico, and Colorado.   This brings the official count to 99 domestic cats (11 from Oregon) along with more than 5 dozen captive and wild `big' cats (bobcats, mountain lions, tigers, etc.). 

Combined, felines make up the largest percentage (31%) of the mammals on the list, followed by rodents (21%), and foxes (20%). 

The latest additions to the list include 10 cats and 1 house mouse. All of these numbers, however, are expected to be substantially undercounted.

Three months ago, in Emerg. Microbes & Inf.: Marked Neurotropism and Potential Adaptation of H5N1 Clade 2.3.4.4.b Virus in Naturally Infected Domestic Cats, we looked at a report on the HPAI H5 infection of a house full of domestic cats (n=8) in South Dakota last April. 

Isolates from the two cats that were tested showed signs of viral adaptation to a mammalian host.  The authors wrote:

Cat H5N1 genomes had unique mutations, including T143A in haemagglutinin, known to affect infectivity and immune evasion, and two novel mutations in PA protein (F314L, L342Q) that may affect polymerase activity and virulence, suggesting potential virus adaptation.

 

Dead cats showed systemic infection with lesions and viral antigens in multiple organs. Higher viral RNA and antigen in the brain indicated pronounced neurotropism.

Until recently, HPAI H5 was pretty much just an avian virus, with only occasional spillovers to humans and a few cats unlucky enough to be fed a diet of raw chicken. But starting in 2021 we began to see reports of numerous spillovers into a much wider range of mammals.

As the HPAI H5 virus continues to find new mammalian hosts it is likely to become more deeply entrenched in our shared ecology, increasing the risks that it will find new evolutionary pathways that were unavailable to it when it was primarily a disease of birds.

Where that takes us is anyone's guess, but it makes it unlikely that HPAI H5 will be going away anytime soon.