ECCMID 2024 Study: Mpox (monkeypox) Antibodies Wane Within A Year of Vaccination

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While we await the next hoof to drop in the HPAI/cattle story, we've other infectious disease news of note. Yesterday, the European Society of Clinical Microbiology and Infectious Diseases published a press release on an upcoming presentation at next month's ECCMID 2024 meeting in Barcelona, Spain.

The Preliminary program lists the study as:

Mpox-specific antibodies wane within one year after MVA-BN vaccination

M.C. Shamier* (Rotterdam, Netherlands), L.P.M. Van Leeuwen, B.E. Verstrepen, K. Wijnans, N. Ahkiyate, H.M. Götz, R.D. De Vries, E.C.M. Van Gorp, M.P.G. Koopmans, S. Goeijenbier, C.H. Geurtsvankessel, L.M. Zaeck

This study found that recipients of the 2-Dose JYNNEOS/ IMVANEX/ IMVAMUNE mpox vaccine who did not receive a childhood smallpox vaccination (discontinued in the 1970s) experienced substantial drops in their immune response after 12 months. 

While the full report has yet to be published, we get early details from the following press release.  I'll have more after the break.

Study shows Mpox (monkeypox) antibodies wane within a year of vaccination

However antibodies remain high in those with pre-existing immunity

Reports and Proceedings

EUROPEAN SOCIETY OF CLINICAL MICROBIOLOGY AND INFECTIOUS DISEASES

New research to be presented at this year’s European Congress of Clinical Microbiology and Infectious Diseases (ECCMID 2024) in Barcelona, Spain (27-30 April) shows that the antibodies produced by Modified Vaccinia virus Ankara - Bavarian Nordic (MVA-BN) vaccination against mpox wane significantly within a year of receiving the vaccination – but in people with pre-existing immunity due to childhood smallpox vaccination in childhood, antibody levels remain high in almost all cases. The study is presented by PhD student Dr. Marc Shamier, Erasmus MC, Rotterdam, Netherlands, from a research team led by Dr Rory de Vries.

During the 2022-2023 mpox outbreak, MVA-BN was rapidly deployed among at-risk populations, including gay, bisexual, and other men who have sex with men (GBMSM). This vaccine is based on a highly attenuated strain of Vaccinia virus (VACV) – a virus that belongs to the orthopoxvirus genus, as do the viruses that cause smallpox (variola virus) and Mpox (monkeypox virus).

Little is known about the longevity of immune responses induced by-MVA-BN vaccination and the impact of prior smallpox vaccination. In this study, the authors assessed the antibody levels response to MVA-BN one year after vaccination. While marketed under various names such as JYNNEOS, IMVANEX, and IMVAMUNE, all are brand names for the same Modified Vaccinia Ankara (MVA)-based vaccine. As such, the immunological effects they confer are expected to be consistent across these products.

Out of the 118 vaccine recipients, 36 (30%) returned for the 1-year follow-up visit. Among individuals without pre-existing immunity, 14/21 (67%) had undetectable levels of VACV IgG and a 10.7-fold decrease in VACV IgG GMT (geometric mean, a standard measurement for antibody levels) was observed compared to the last time point after vaccination in 2022 (4 weeks after the second dose) (Figure 1 full abstract).

In contrast, among individuals with childhood smallpox vaccination, only one participant out of 15 (7%) had undetectable VACV IgG after one year, and the GMT reduction between 4 weeks after the last vaccine dose in 2022 and the one-year follow-up visit was 2.5-fold for those vaccinated with two doses of MVA-BN, and 1.9-fold for those vaccinated with one dose of MVA-BN.

The authors say: “A rapid decline in VACV-specific IgG antibodies was observed one year after MVA-BN vaccination, leading to loss of detectable antibodies in 42% (15/36) of the participants. This reduction was most pronounced in individuals without pre-existing immunity. As the mechanism of protection for mpox remains undefined, the implications of waning antibody levels for conferring protection remain uncertain.”

The authors suggest that the decrease in antibodies over time following MVA-BN vaccination may be attributable its composition. They say: “The first and second-generation smallpox vaccines contained replication-competent vaccinia virus. MVA-BN is based on non-replicating virus, which may impact the strength and duration of the immune response; with the advantage of a low risk of side effects.”

They add: “Regarding the potential necessity for a booster, it is premature to draw such conclusions. It is unclear how waning antibody levels relate to protection. Immunity also involves other elements, such as T-cell responses. Comprehensive clinical monitoring over time, which connects infection rates with antibody levels, is required to make informed decisions about booster vaccination protocols.”

Admittedly, the JYNNEOS vaccine - which was first approved in 2019 - was never expected to be 100% protective against Mpox (see MMWR: Five Recent Reports On Mpox Outbreaks & Vaccine Effectiveness), and the CDC has previously acknowledged:

Peak immunity is expected to be reached 14 days after the second dose of JYNNEOS vaccine. The duration of immunity after one or two doses of JYNNEOS is currently unknown.

While the waning of detectable antibodies after a year is disappointing - it is still possible that some degree of protection remains - particularly against severe disease. 

Although the global health emergency over the international spread of a new clade (IIb) of Mpox (formerly Monkeypox) was declared over 11 months ago, we continue to see sporadic infections around the globe, while a more dangerous clade I mpox virus continues to rage ( > 12,000 cases in 2023) in the DRC.

Four months ago, the WHO Reported the 1st Confirmed Cluster Of Sexually Transmitted MPXV Clade 1 in the DRC, warning that `The risk of mpox further spreading to neighbouring countries and worldwide appears to be significant.'

Earlier this month we looked at a report in Eurosurveillance: Ongoing Mpox Outbreak in South Kivu Province, DRC Associated With a Novel Clade I Sub-lineage, which contained the first genomic analysis of samples from a previously unaffected region of the DRC. 

This study revealed a novel clade I sub-linage had emerged - most likely from a zoonotic introduction - with changes that may render current CDC tests unreliable.

Like all viruses, Monkeypox continues to evolve and diversify, as discussed in the 2014 EID Journal article Genomic Variability of Monkeypox Virus among Humans, Democratic Republic of the Congo, where the authors cautioned:

Small genetic changes could favor adaptation to a human host, and this potential is greatest for pathogens with moderate transmission rates (such as MPXV) (40). The ability to spread rapidly and efficiently from human to human could enhance spread by travelers to new regions.

While Mpox has largely fallen out of the news cycle, it hasn't gone away.  And given its ability to reinvent itself over time, could easily begin another world tour.

CDC: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations Of HPAI H5N1 In Animals

Credit NIAID

 

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Over the past few months, with the escalating threat of HPAI exposure via infected migratory birds, we've discussed the `new normal' in which we find ourselves, and the precautions that many of us living in North and South America, and much of Europe, are unfamiliar with (see here, here, and here). 

Since last week, we've learned that cattle and goats - previously assumed to be at low risk of contracting avian flu - are being infected across multiple states.   Potentially worse, there are some signs that cow-to-cow transmission may have occurred. 

Whether this signals a subtle change in how the HPAI H5 virus infects and spreads - or is simply the result of unusually high environmental contamination from infected birds - it means that the risks of exposure for other livestock, our pets, and even ourselves has likely increased. 

Overnight the CDC has released extensive guidance - for the public, for public health officials, and for clinicians - on dealing with this increased risk.  Included are epidemiological and clinical criteria for use in identifying and treating potential patients. 

I've reproduced the bulk of the guidance below, but you'll want to follow the link to get the full set of links and references.  I'll have a brief postscript after the break.

Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations

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Summary
Background
Recommendations for the Public
Recommendations for Farmers
Recommendations for Clinicians
Recommendations for State Health Departments
Recommendations for Surveillance and Testing
Recommendations for Infection Prevention and Control
Recommendations for Influenza Antiviral Treatment and Chemoprophylaxis
Vaccinations
Attribution Statement

Summary

The purpose of this guidance is to outline CDC’s recommendations for preventing exposures to highly pathogenic avian influenza (HPAI) A(H5N1) viruses, infection prevention and control measures including the use of personal protective equipment, testing, antiviral treatment, patient investigations, monitoring of exposed persons, including persons exposed to sick or dead wild and domesticated animals and livestock with suspected or confirmed infection with highly pathogenic avian influenza (HPAI) A(H5N1) virus, and antiviral chemoprophylaxis of exposed persons. These recommendations are based on information available as of March 2024 and will be updated as needed when new information becomes available.

Background

Although human infections with HPAI A(H5N1) virus are rare, having unprotected exposure to any infected animal or to an environment in which infected birds or other animals are or have been present can pose a risk of infection. Therefore, people with work or recreational exposures to H5N1 virus-infected animals may be at increased risk of infection and should follow recommended precautions.

The panzootic of HPAI A(H5N1) viruses in wild birds has resulted in outbreaks among commercial poultry, backyard bird flocks, and spread to infect wild terrestrial and marine mammals, as well as domesticated animals. Sporadic human infections with HPAI A(H5N1) virus have been reported in 23 countries since 1997 with a case fatality proportion of >50%, but only a small number of H5N1 cases have been reported in humans since 2022. Most human infections with H5N1 virus have occurred after unprotected exposures to sick or dead infected poultry. There is no evidence of sustained human-to-human H5N1 virus transmission, and limited, non-sustained human-to-human H5N1 virus transmission has not been reported worldwide since 2007.

Influenza A viruses infect the respiratory and gastrointestinal tracts of birds causing birds to shed the virus in their saliva, mucous, and feces. Influenza A viruses can also infect the respiratory tract of mammals and cause systemic infection in other organ tissues. Human infections with avian influenza A viruses can happen when enough virus gets into a person’s eyes, nose, or mouth or is inhaled. People with close or prolonged unprotected contact with infected birds or animals or their contaminated environments are at greater risk of infection. Illnesses in people from HPAI A(H5N1) virus infections have ranged from mild (e.g., upper respiratory symptoms) to severe illness (e.g., pneumonia, multi-organ failure) resulting in death.

Since 2022, many different wild bird species have been reported with HPAI A(H5N1) virus infection, including terrestrial, seabird, shorebird, and migratory species. In the United States, HPAI A(H5N1) virus detections in wild birds have been reported in 50 states or territories, and outbreaks in commercial poultry or backyard bird flocks associated with high mortality have been reported in 48 states since February 2022.

A wide range of terrestrial and marine mammals have been reported with HPAI A(H5N1) virus infection in multiple countries, typically resulting in neurologic signs of disease and death. HPAI A(H5N1) virus infection has been reported in wild mammals such as foxes, bears, seals, and sea lions, and in domesticated animals, including pets such as cats and dogs, farmed mink and foxes, and livestock such as goats and cows. In the United States, HPAI A(H5N1) virus detections in mammals have been reported in more than 20 states.

At this time, CDC considers the human health risk to the U.S. public from HPAI A(H5N1) viruses to be low; however, people with close or prolonged, unprotected exposures to infected birds or other animals, or to environments contaminated by infected birds or other animals, are at greater risk of infection. CDC considers HPAI A(H5N1) viruses to have the potential to cause severe disease in infected humans and recommends the following:

Recommendations for the Public

People should avoid unprotected (not using respiratory or eye protection) exposures to sick or dead animals including wild birds, poultry, other domesticated birds, and other wild or domesticated animals, as well as with animal feces, litter, or materials contaminated by birds or other animals with suspected or confirmed HPAI A(H5N1) virus infection. People should not prepare or eat uncooked or undercooked food or related uncooked food products, such as unpasteurized (raw) milk, or raw cheeses, from animals with suspected or confirmed HPAI A(H5N1) virus infection (avian influenza or bird flu).

Personal protective equipment (PPE) should be worn when in direct or close contact (within about six feet) with sick or dead animals including poultry, wild birds, backyard bird flocks, or other animals, animal feces, litter, or materials potentially contaminated with HPAI A(H5N1) viruses. PPE includes a properly fitted unvented or indirectly vented safety goggles, disposable gloves, boots or boot covers, a NIOSH-Approved particulate respirator (e.g., N95® filtering facepiece respirator, ideally fit-tested), disposable fluid-resistant coveralls, and disposable head cover or hair cover.

People exposed to HPAI A(H5N1)-virus infected birds or other animals (including people wearing recommended PPE) should monitor themselves for new respiratory illness symptoms, including conjunctivitis (eye redness), beginning after their first exposure and for 10 days after their last exposure. Influenza antiviral post-exposure prophylaxis may be considered to prevent infection, particularly in those who had unprotected exposure to HPAI A(H5N1)-virus infected birds or other animals (see below). Persons who develop any illness symptoms after exposure to HPAI A(H5N1) virus infected birds or other animals should seek prompt medical evaluation for possible influenza testing and antiviral treatment by their clinician or public health department. Symptomatic persons should isolate away from others, including household members, except for seeking medical evaluation until it is determined that they do not have HPAI A(H5N1) virus infection.

Recommendations for Farmers; Poultry, Backyard Bird Flock, and Livestock Owners; and Worker Protection

To reduce the risk of HPAI A(H5N1) virus infection, poultry farmers and poultry workers, backyard bird flock owners, livestock farmers and workers, veterinarians and veterinary staff, and responders should avoid unprotected direct physical contact or close exposure with sick or dead birds or other animals, carcasses, feces, milk, or litter from sick birds or other animals potentially infected or confirmed to be infected with HPAI A(H5N1) virus.

Farmers, workers, and responders should wear recommended PPE such as an N95 filtering facepiece respirator, eye protection, and gloves, and perform thorough hand washing after contact. (e.g., see: PPE recommended for poultry workers) when in direct contact with sick or dead birds or other animals, carcasses, feces, or litter from potentially infected birds or other animals, and when going into any buildings with or that have had sick or dead birds or other animals, carcasses, feces, or litter from potentially infected birds or other animals. Workers should receive training on and demonstrate an understanding of when to use PPE; what PPE is necessary; how to properly put on, use, take off, dispose of, and maintain PPE; and PPE limitations. Employers subject to Occupational Safety and Health Administration (OSHA) regulations should comply with applicable standards as highlighted on the OSHA Avian Influenza – Standards page.

Recommendations for Clinicians

Clinicians should consider the possibility of HPAI A(H5N1) virus infection in persons showing signs or symptoms of acute respiratory illness who have relevant exposure history. See: Brief summary for Clinicians. This includes persons who have had contact with potentially infected sick or dead birds, livestock, or other animals within the week before symptom onset (e.g., handling, slaughtering, defeathering, butchering, culling, preparing for consumption or consuming uncooked or undercooked food or related uncooked food products, including unpasteurized (raw) milk or other unpasteurized dairy products), direct contact with water or surfaces contaminated with feces, unpasteurized (raw) milk or unpasteurized dairy products, or parts (carcasses, internal organs, etc.) of potentially infected animals; and persons who have had prolonged exposure to potentially infected birds or other animals in a confined space. Clinicians should contact the state public health department to arrange testing for influenza A(H5N1) virus, collect recommended respiratory specimens (see below) using PPE, consider starting empiric antiviral treatment (see below), and encourage the patient to isolate at home away from their household members and not go to work or school until it is determined they do not have avian influenza A virus infection. Testing for other potential causes of acute respiratory illness should also be considered depending upon the local epidemiology of circulating respiratory viruses, including SARS-CoV-2.

Recommendations for State Health Departments

State health department officials should investigate potential human cases of HPAI A(H5N1) virus infection as described below and should notify CDC within 24 hours of identifying a case under investigation. Rapid detection and characterization of novel influenza A viruses in humans remain critical components of national efforts to prevent further cases, to allow for evaluation of clinical illness associated with them, and to assess the ability of these viruses to spread from human to human. State Health Department officials, including the State Public Health Veterinarian, should collaborate with State Department of Agriculture and State Wildlife officials using a One Health approach when relevant to investigate suspected HPAI A(H5N1) infections in people linked with animals.

Recommendations for Surveillance and Testing

People exposed to HPAI A(H5N1)-infected birds or other animals (including people wearing recommended PPE) should be monitored for signs and symptoms of acute respiratory illness beginning after their first exposure and for 10 days after their last exposure.

Patients who meet Epidemiologic criteria AND either Clinical OR Public Health Response criteria below should be tested for HPAI A(H5N1) virus infection by reverse-transcription polymerase chain reaction (RT-PCR) assay using H5-specific primers and probes at your state or local public health department.

Epidemiological Criteria

Persons with recent exposure (within 10 days) to HPAI A(H5N1) virus through one of the following:

• Exposure to HPAI A(H5N1) virus infected birds or other animals defined as follows:

• Close exposure (within six feet) to birds or other animals, with confirmed avian influenza A(H5N1) virus infection. Bird or other animal exposures can include, but are not limited to handling, slaughtering, defeathering, butchering, culling, or preparing birds or other animals for consumption, or consuming uncooked or undercooked food or related uncooked food products, including unpasteurized (raw) milk,

OR

Direct contact with surfaces contaminated with feces, unpasteurized (raw) milk or other unpasteurized dairy products, or bird or animal parts (e.g., carcasses, internal organs) from infected birds or other animals

OR

• Visiting a live bird market with confirmed bird infections or associated with a case of human infection with HPAI A(H5N1) virus.
• Exposure to an infected person – Close (within six feet) unprotected (without use of respiratory and eye protection) exposure to a person who is a confirmed, probable, or symptomatic suspected case of human infection with HPAI A(H5N1) virus (e.g., in a household or healthcare facility).
• Laboratory exposure (unprotected exposure to HPAI A(H5N1) virus in a laboratory)

Clinical Criteria

Persons with signs and symptoms consistent with acute upper or lower respiratory tract infection, or complications of acute respiratory illness without an identified cause. In addition, gastrointestinal symptoms such as diarrhea are often reported with HPAI A(H5N1) virus infection. Examples include but are not limited to:

• Mild illness (e.g., cough, sore throat, eye redness or eye discharge such as conjunctivitis, fever or feeling feverish, rhinorrhea, fatigue, myalgia, arthralgia, headache)
• Moderate to severe illness: (e.g., shortness of breath or difficulty breathing, altered mental status, seizures)
• Complications: pneumonia, respiratory failure, acute respiratory distress syndrome, multi-organ failure (respiratory and kidney failure), sepsis, meningoencephalitis

Public Health Response Criteria

Testing of asymptomatic persons for HPAI A(H5N1) virus infection is not routinely recommended. As part of public health investigations, asymptomatic persons, such as close contacts of a confirmed case of HPAI A(H5N1) virus infection, might be tested after consultation with CDC.

Preferred Clinical Specimens

For persons with suspected HPAI A(H5N1) virus infection, the following specimens should be collected as soon as possible after illness onset or when deemed necessary: a nasopharyngeal swab and a nasal swab combined with an oropharyngeal swab (e.g., two swabs combined into one viral transport media vial). The nasopharyngeal swab and the combined nasal-throat swabs should be tested separately. If these specimens cannot be collected, a single nasal or oropharyngeal swab is acceptable. If the person has conjunctivitis (with or without respiratory symptoms), both a conjunctival swab and nasopharyngeal swab should be collected. Patients with severe respiratory disease also should have lower respiratory tract specimens (e.g., an endotracheal aspirate or bronchoalveolar lavage fluid) collected, if possible. For severely ill persons, multiple respiratory tract specimens from different sites should be obtained to increase the potential for HPAI A(H5N1) virus detection.

Recommendations for Infection Prevention and Control

Standard, contact, and airborne precautions are recommended for patients presenting for medical care or evaluation who have illness consistent with influenza and recent exposure to birds or other animals potentially infected with HPAI A(H5N1) virus. For additional guidance on infection prevention and control precautions for patients who might be infected with HPAI A(H5N1) virus, please refer to guidance for infections with novel influenza A viruses associated with severe disease.

Recommendations for Influenza Antiviral Treatment and Chemoprophylaxis

Treating Symptomatic Persons with Bird or Other Animal Exposures

Outpatients meeting epidemiologic exposure criteria who develop signs and symptoms compatible with influenza should be referred for prompt medical evaluation, testing, and empiric initiation of antiviral treatment with oseltamivir as soon as possible. Clinical benefit is greatest when antiviral treatment is administered early, especially within 48 hours of illness onset.

Hospitalized patients who are confirmed, probable, or suspected cases of human infection with HPAI A(H5N1) virus, regardless of time since illness onset are recommended to initiate antiviral treatment with oral or enterically administered oseltamivir as soon as possible. Antiviral treatment should not be delayed while waiting for laboratory testing results.

For detailed guidance on dosing and treatment duration, please see Interim Guidance of the Use of Antiviral Medications for the Treatment of Human Infection with Novel Influenza A Viruses Associated with Severe Human Disease.

Chemoprophylaxis of Persons with Exposure to HPAI A(H5N1) Virus: Chemoprophylaxis with influenza antiviral medications can be considered for any person meeting epidemiologic exposure criteria. Decisions to initiate post-exposure antiviral chemoprophylaxis should be based on clinical judgment, with consideration given to the type of exposure, duration of exposure, time since exposure, and known infection status of the birds or animals the person was exposed to.

Antiviral chemoprophylaxis is not routinely recommended for personnel who used proper PPE and experienced no breaches while handling sick or potentially infected birds or other animals or decontaminating infected environments (including animal disposal).

If antiviral chemoprophylaxis is initiated, oseltamivir treatment dosing (one dose twice daily) is recommended instead of the antiviral chemoprophylaxis regimen for seasonal influenza. For specific dosage recommendations for treatment by age group, please see Influenza Antiviral Medications: Summary for Clinicians. Physicians should consult the manufacturer’s package insert for dosing, limitations of populations studied, contraindications, and adverse effects. If exposure was time-limited and not ongoing, five days of medication (one dose twice daily) from the last known exposure is recommended.

Monitoring and Antiviral Chemoprophylaxis of Close Contacts of Persons with HPAI A(H5N1) virus infection: Recommendations for monitoring and chemoprophylaxis of close contacts of infected persons are different than those that apply to persons who meet bird or other animal exposure criteria. Post-exposure prophylaxis of close contacts of a person with HPAI A(H5N1) virus infection is recommended with oseltamivir twice daily (treatment dosing) instead of the once daily pre-exposure prophylaxis dosing. For detailed guidance, please see Interim Guidance on Follow-up of Close Contacts of Persons Infected with Novel Influenza A Viruses and Use of Antiviral Medications for Chemoprophylaxis.

Vaccination

No human vaccines for prevention of HPAI A(H5N1) virus infection are currently available in the United States. Seasonal influenza vaccines do not provide any protection against human infection with HPAI A(H5N1) viruses.

Since testing of cattle (and goats) for HPAI is only rarely done (at least, until now), we don't really know how long H5N1 has been infecting cattle or how widespread it may be. There are reports of `sick cows' going back to January or February in Texas, without an obvious cause.

As we've discussed previously (see A Brief History Of Influenza A In Cattle/Ruminants) influenza infection in cattle is believed to be rare, but is not unheard of.

 

Until more testing can be completed, we also don't know if some cows are being asymptomatically infected.

Simply put, the more we test, the more we will learn. But there are practical limits to surveillance and testing, and much of what the virus is doing in the wild will remain forever outside of our view. 

Which means we should be prepared for more surprises in the future. 

USDA/CDC/FDA & MDARD Statements On HPAI In Dairy Cattle - Michigan Herd Tests Positive

 
Michigan - Credit Wikipedia

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Late last night we learned that cows a dairy farm in Idaho had tested positive for HPAI (see Idaho Ag Dept.: HPAI Detection in Idaho Dairy Herd) bringing the number of states reporting infected dairy cows to 4 (Texas, Kansas, New Mexico & Idaho). 

Of note, the ISDA specifically mentioned the possibility of cow-to-cow transmission, as the affected facility had recently imported cows from another state which is now reporting HPAI in cattle.

This afternoon the USDA, CDC and FDA released a joint announcement adding Michigan to the list, and once again the possibility of cow-to-cow transmission is mentioned.  First the full text of this afternoon's statement, followed by a statement from Michigan's Department of Agriculture & Rural Development (MDARD).

USDA, FDA and CDC Share Update on HPAI Detections in Dairy Cattle
Published: Mar 29, 2024

WASHINGTON, March 29, 2024 – The U.S. Department of Agriculture (USDA), Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC), as well as state veterinary and public health officials, are continuing to investigate an illness among dairy cows that is causing decreased lactation, low appetite, and other symptoms.

On Monday, March 25, the agencies confirmed the detection of highly pathogenic avian influenza (HPAI) in two dairy herds in Texas and two dairy herds in Kansas that had cattle exhibiting these symptoms.

USDA’s National Veterinary Services Laboratories (NVSL) has now also confirmed the presence of HPAI in a Michigan dairy herd that had recently received cows from Texas. Presumptive positive test results have also been received for additional herds in New Mexico, Idaho, and Texas; USDA will share updates if those tests are confirmed positive by NVSL. Federal and state agencies continue to conduct additional testing in swabs from sick animals and in unpasteurized clinical milk samples from sick animals, as well as viral genome sequencing, to assess whether HPAI or another unrelated illness may be underlying any symptoms

The NVSL has also confirmed that the strain of the virus found in Michigan is very similar to the strain confirmed in Texas and Kansas that appears to have been introduced by wild birds (H5N1, Eurasian lineage goose/Guangdong clade 2.3.4.4b). Initial testing has not found changes to the virus that would make it more transmissible to humans. While cases among humans in direct contact with infected animals are possible, this indicates that the current risk to the public remains low.

Spread of symptoms among the Michigan herd also indicates that HPAI transmission between cattle cannot be ruled out; USDA and partners continue to monitor this closely and have advised veterinarians and producers to practice good biosecurity, test animals before necessary movements, minimize animal movements, and isolate sick cattle from the herd. Among the dairies whose herds are exhibiting symptoms, the affected animals have recovered after isolation with little to no associated mortality reported.

There continues to be no concern about the safety of the commercial milk supply because products are pasteurized before entering the market, or that this circumstance poses a risk to consumer health. Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted or destroyed so that it does not enter the human food supply. In addition, pasteurization has continually proven to inactivate bacteria and viruses, like influenza, in milk. Pasteurization is required for any milk entering interstate commerce for human consumption. FDA’s longstanding position is that unpasteurized, raw milk can harbor dangerous microorganisms that can pose serious health risks to consumers, and FDA is reminding consumers of the risks associated with raw milk consumption in light of the HPAI detections.

Because of the limited information available about the transmission of HPAI in raw milk, the FDA recommends that industry does not manufacture or sell raw milk or raw/unpasteurized milk cheese products made with milk from cows showing symptoms of illness, including those infected with avian influenza or exposed to those infected with avian influenza. At this time, the FDA is not aware that any milk or food product from symptomatic cows is entering interstate commerce. Furthermore, if milk from cows showing symptoms of illness, including those infected with avian influenza or exposed to those infected with avian influenza is intended to be used to feed calves, FDA strongly encourages that it be heat treated to kill harmful bacteria or viruses, such as influenza, before calf feeding. Food safety information from FDA, including information about the sale and consumption of raw milk, can be found here.

Milk loss resulting from symptomatic cattle to date is too limited to have a major impact on supply and there should be no impact on the price of milk or other dairy products. Further, the U.S. typically has a more than sufficient milk supply in the spring months due to seasonally higher production.


Federal agencies are also working with state and industry partners to encourage farmers and veterinarians to report cattle illnesses quickly so that we can monitor potential additional cases and minimize the impact and risk to farmers, farmworkers, consumers and other animals. Producers are urged to work with their veterinarian to report cattle illnesses quickly and practice enhanced biosecurity measures. More information on biosecurity measures can be found here.

Highly Pathogenic Avian Influenza Detected in Michigan Dairy Herd

March 29, 2024

Michigan herd is linked to the affected cattle in Texas; producers are strongly encouraged to contact their veterinarian about any animal health concern

LANSING, MI – Today, Michigan Department of Agriculture and Rural Development (MDARD) Director Tim Boring announced the detection of highly pathogenic avian influenza (HPAI) in a dairy herd from Montcalm County. The U.S. Department of Agriculture’s National Veterinary Services Laboratories has confirmed this detection.

Further testing and investigation by state and federal officials have revealed the source of infection. The farm recently received cattle from an affected premises in Texas before that herd showed any sign of disease. When the cattle were moved from Texas to Michigan, the cattle were not symptomatic and did not appear ill. As this national situation continues to develop, it is essential for all producers to contact their veterinarian if they have any concerns regarding the health of their animals, regardless of species.

"We have well-trained staff responding to this situation and I have the utmost confidence in our team. We will continue working with our local, state, and national partners to protect animal and public health," said Director Boring. "Our highest priorities at MDARD remain protecting our food supply and ensuring animal health. As this situation evolves, we will provide critical updates to producers, industry, and all Michiganders.”

“This case does reflect a lot of what is already known about this virus—namely, that it is highly contagious, it continues to be primarily spread by wild birds and contact with infected animals, and mammals can contract the virus,” said State Veterinarian Dr. Nora Wineland, DVM, MS, DACVPM. “MDARD is working diligently and in close collaboration with government partners, producer groups, and Michigan dairy farmers to address the situation and prevent the spread of disease. As more is learned, it is vitally important for producers to work with their veterinarian and isolate sick animals from others, minimize the number of visitors to their farms, prevent contact between their animals and wildlife, and continue to vigilantly monitor the health of their animals.”

HPAI is a highly contagious virus that can be spread directly by infected wild birds/animals or indirectly through any item that has been exposed to the virus—such as equipment, feed, or the clothing and shoes of caretakers. The virus has been detected in various species of mammals—presumably after the animals come into contact with infected birds. To limit the spread of the disease, the affected premises voluntarily stopped movement.

Producers who have concerns about the health of their animals and/or questions regarding how to improve the measures they take to protect animal health on their farm should contact their veterinarian. Also, if cattle producers notice decreased lactation, low appetite, and/or other symptoms in their herds, please contact your veterinarian to determine the next appropriate steps to take.

Analysis of the virus from this case and the other cases of affected cattle has not shown any significant new adaptation to make the virus more transmissible between mammals. Therefore, the public health risk associated with HPAI remains low.

According to the Food and Drug Administration and Centers for Disease and Prevention, the commercial milk supply remains safe due to both federal animal health requirements and pasteurization.

If anyone suspects the presence of HPAI or any other reportable animal disease in their domestic animals, please contact MDARD immediately at 800-292-3939 (daytime) or 517-373-0440 (after-hours).

For more information on the detections of HPAI in cattle, please visit the U.S. Department of Agriculture’s website.

Since cattle are not routinely tested for HPAI, it is entirely possible that increased surveillance and testing will reveal additional outbreaks.  

Stay tuned.

CDC FluView Wk #12: 1 Novel H1N2v Infection In Pennsylvania

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While the continued spillover of HPAI H5 into mammals has garnered most of our attention this week, the CDC is reporting in today's weekly FluView the first confirmed swine variant (H1N2v) human infection of 2024 in the United States. 

Over the past dozen years we've seen roughly 500 swine variant cases (H1N1v, H1N2v, H3N2v) reported by the CDC, and last summer the CDC held a webinar for clinicians on recognizing, treating, and reporting zoonotic influenza cases in the community (see COCA Call : What Providers Need to Know about Zoonotic Influenza).

The CDC describes Swine Variant viruses in their Key Facts FAQ.

What is a variant influenza virus?

When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant influenza virus.” For example, if a swine origin influenza A H3N2 virus is detected in a person, that virus will be called an “H3N2 variant” virus or “H3N2v” virus. 

 Details on this latest case follow:

Novel Influenza A Virus:

A human infection with a novel influenza A virus was reported by the Pennsylvania Department of Health. The patient was infected with an influenza A(H1N2) variant (A(H1N2)v) virus. The patient is < 18 years of age, sought healthcare during the week ending March 9, 2024 (week 10), was hospitalized, and has since recovered.

An investigation by local public health officials found that the patient had swine contact prior to their illness onset. Additional investigation identified mild illness in two of the patient’s close contacts who also had contact with swine, that began prior to the patient’s onset of symptoms. No person-to-person transmission of A(H1N2)v virus associated with this patient has been identified. The investigation is ongoing. This is the first human infection with a variant influenza A virus reported in the United States in 2024.

When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant” influenza virus. Most human infections with variant influenza viruses occur following exposure to swine, but human-to-human transmission can occur. It is important to note that in most cases, variant influenza viruses have not shown the ability to spread easily and sustainably from person to person.

Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be understood, and appropriate public health measures can be taken.

Additional information on influenza in swine, variant influenza virus infection in humans, and guidance to interact safely with swine can be found at www.cdc.gov/flu/swineflu/index.htm.

Additional information regarding human infections with novel influenza A viruses:

Surveillance Methods | FluView Interactive

With few exceptions (i.e. the 2009 H1N1 pandemic virus), current swine influenza viruses don't appear to spread efficiently in humans. That said, the CDC's IRAT (Influenza Risk Assessment Tool) lists 3 North American swine viruses as having at least some pandemic potential (2 added in 2019).

H1N2 variant [A/California/62/2018] Jul 2019 5.8 5.7 Moderate

H3N2 variant [A/Ohio/13/2017] Jul 2019 6.6 5.8 Moderate 

H3N2 variant [A/Indiana/08/2011] Dec 2012 6.0 4.5 Moderate

In recent years we are seeing a rise in H1N2v infections, while prior to 2017 H3N2v was the most commonly reported swine variant virus. The CDC currently ranks a Chinese Swine-variant EA H1N1 `G4' as having the highest pandemic potential of any flu virus on their list. 

But, as with avian flu, they all have barriers they must overcome.

While Swine-variant (typically H1N1v, H1N2v, H3N2v) infections are generally mild, the CDC routinely advises those who are at higher risk of serious flu complications (including children under 5, adults over 65, pregnant women, and those with certain chronic medical conditions), to avoid pigs and the swine barn altogether.

Some recent blogs on swine variant viruses include:

Virology: Novel Influenza A Viruses in Pigs with Zoonotic Potential, Chile

Virologica Sinica: The Evolution, Pathogenicity & Transmissibility of Quadruple Reassortant H1N2 Swine Influenza Virus in China

WHO Update & Risk Assessment: H1N1v Case In Brazil

Eurosurveillance: A Case of Swine Influenza A(H1N2)v in England, November 2023

CDC Updated Advice On Bird Flu in Pets and Other Animals

#17,973

Recent reports suggesting that Vietnam's latest fatal H5N1 case may have contracted the virus through contact with wild birds, and other similar reports in the past (see here and here), have public health agencies once again reminding people of the potential risks to them, and their pets, from avian influenza.

Ten days ago we looked at the UK Guidance for the Public: Minimize Contact with Wild Birds that stressed avoiding contact, and when that isn't possible, the value of wearing of PPEs (gloves, eye protection & masks, etc.), and the importance of post-contact disinfection.

While the risks of infection to dogs and cats (and their owners) is considered low, it is not zero (see J. Virulence: HPAI H5N1 Virus Infection In Companion Animals), and cat-to-human transmission has been reported (see EID Journal: Avian H7N2 Virus in Human Exposed to Sick Cats).

With the recent revelation that HPAI H5 has been detected in two previously unreported farm animals (goats and cows), the need for public vigilance has only increased. 

The CDC has recently (March 21st) updated their advice to the public on bird flu in pets and other animals, excerpts of which you'll find below.

Bird Flu in Pets and Other Animals

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Pet Owners

People Who Have Had Direct Contact with Infected or Potentially Infected Animals


Although bird flu viruses mainly infect and spread among wild migratory water birds and domestic poultry, some bird flu viruses can infect and spread to other animals as well.

Bird flu viruses have in the past been known to sometimes infect mammals that eat (presumably infected) birds or poultry, including but not limited to wild animals, such as seals, bears, foxes, skunks; farmed mink; stray or domestic animals, such as cats and dogs; and zoo animals, such as tigers and leopards.

H5N1 bird flu viruses have been detected sporadically in some domestic animals, including cats during outbreaks in Thailand in 2004 and Northern Germany in 2006, and cats, dogs, and goat kids (juvenile goats) in North America. In December 2023, H5N1 virus infections were reported for the first time in mammals in both polar regions: an infected polar bear, which died in Alaska, and in elephant and fur seals in the Antarctic.

While it’s unlikely that people would become infected with bird flu viruses through contact with an infected wild, stray, feral, or domestic mammal, it is possible—especially if there is prolonged and unprotected exposure to the animal. This page provides information for different groups of people who might have direct contact with infected or potentially infected sick or dead animals, including animals that might have eaten or been exposed to bird flu-infected birds.

Pet Owners

If your domestic animals (e.g., cats or dogs) go outside and could potentially eat or be exposed to sick or dead birds infected with bird flu viruses, or an environment contaminated with bird flu virus, they could become infected with bird flu. While it’s unlikely that you would get sick with bird flu through direct contact with your infected pet, it is possible. For example, in 2016, the spread of bird flu from a cat to a person was reported in NYC. The person who was infected [2.29 MB, 4 pages] was a veterinarian who had mild flu symptoms after prolonged exposure to sick cats without using personal protective equipment.

If your pet is showing signs of illness compatible with bird flu virus infection and has been exposed to infected (sick or dead) wild birds/poultry, you should monitor your health for signs of fever or infection.

More Information

Influenza in Cats | Seasonal Influenza (Flu) | CDC

Healthy Pets, Healthy People

Avian Influenza in Companion Animals | American Veterinary Medical Association

Backyard Flock Owners: Take Steps to Protect Yourself from Avian nfluenza 

Take precautions to prevent the spread of bird flu.

As a general precaution, people should avoid direct contact with wild birds and observe wild birds only from a distance, whenever possible. People should also avoid contact between their pets (e.g., pet birds, dogs and cats) with wild birds. Don’t touch sick or dead birds, their feces or litter, or any surface or water source (e.g., ponds, waterers, buckets, pans, troughs) that might be contaminated with their saliva, feces, or any other bodily fluids without wearing personal protective equipment (PPE).

More information about specific precautions to take for preventing the spread of bird flu viruses between animals and people is available at Prevention and Antiviral Treatment of Bird Flu Viruses in People. Additional information about the appropriate PPE to wear is available at Backyard Flock Owners: Take Steps to Protect Yourself from Avian Influenza.

People Who Have Had Direct Contact with Infected or Potentially Infected Animals

During outbreaks of bird flu in wild birds and/or poultry, people who have had direct contact with infected or potentially infected animals, including sick animals that might have eaten bird flu-infected birds, should monitor their health for fever and symptoms of infection.

Signs and Symptoms may include:

• Fever (Temperature of 100°F [37.8°C] or greater) or feeling feverish/chills*
• Cough
• Sore throat
• Difficulty breathing/Shortness of breath
• Conjunctivitis (eye tearing, redness, irritation, or discharge from eye)
• Headaches
• Runny or stuffy nose
• Muscle or body aches
• Diarrhea

*Fever may not always be present

Call your state/local health department immediately if you develop any of these signs or symptoms during the 10-days after your exposure to an infected or potentially infected animal. Discuss your potential exposure and ask about testing. If testing is recommended, isolate as much as possible until test results come back and/or you have recovered from your illness.

Additionally, close contacts (family members, etc.) of people who have been exposed to a person or animal with lab-confirmed bird flu viruses should also monitor their health for 10 days after their exposure for signs and symptoms of illness. If close contacts of people who have been exposed to H5 bird flu viruses develop signs and symptoms of illness, they should also contact their state health department. precautions to prevent the spread of bird flu.

(Continue . . . )

 

Idaho Ag Dept.: HPAI Detection in Idaho Dairy Herd

 

Cassia Count, ID Credit Wikipedia

#17,972

Overnight Treyfish and other volunteer newshounds on FluTrackers posted media and official reports (see thread here) on the detection of HPAI in a dairy herd in yet another state: Idaho.  

Unlike previous official statements, which have strongly suggested wild birds as the source of these infections, Idaho's State Department of Agriculture (ISDA) specifically mentions the possibility of cow-to-cow transmission. 

They report that the affected facility had recently imported cows from another state which is now reporting HPAI in cattle, and they may be the source of local infection.  

All of this is quite preliminary, but if the virus is found to be transmitting from cow-to-cow, that would be a worrisome development. 

First the press release from the ISDA, after which I'll have a bit more.

HPAI Detection in Idaho Dairy Herd

Boise, Idaho – The Idaho State Department of Agriculture (ISDA) identified today highly pathogenic avian influenza (HPAI) in a Cassia County dairy cattle operation.

These are the first cases of HPAI in a livestock operation in Idaho. The affected facility recently imported cattle from another state that has identified cases of HPAI in cattle, which suggests the virus may be transmitted from cow-to-cow, in addition to previous reports indicating cattle were acquiring the virus from infected birds.

The primary concern with this diagnosis is on-farm production losses, as the disease has been associated with decreased milk production.

Symptoms of HPAI in cattle include:

• Drop in milk production
• Loss of appetite
• Changes in manure consistency
• Thickened or colostrum-like milk
• Low-grade fever

At this stage, there is no concern about the safety of the commercial milk supply or that this circumstance poses a risk to consumer health. The pasteurization process of heating milk to a high temperature ensures milk and dairy products can be consumed safely.

The ISDA encourages all dairy producers to closely monitor their herd and contact their local veterinarian immediately if cattle appear to show symptoms. HPAI is a mandatory reportable disease, and any Idaho veterinarians who suspect cases of HPAI in livestock should immediately report it to ISDA at 208-332-8540 or complete the HPAI Livestock Screen at agri.idaho.gov/main/animals/hpai/.

It is recommended to enhance biosecurity measures across all livestock facilities in Idaho. Biosecurity practices can be found at agri.idaho.gov/main/animals/hpai/.

For decades, Idaho has worked diligently to implement industry-driven programs that mitigate the transmission of diseases that cause on-farm economic losses. ISDA’s response to the detection of HPAI in cattle aligns with standard ISDA animal disease detection procedure.

This is an evolving situation, and additional updates will be provided by ISDA as they become available.

For more information visit agri.idaho.gov/main/animals/hpai/ or contact ISDA Animal Industries Division (208) 332-8540.

Media Inquiries

Sydney Kennedy
media@isda.idaho.gov
(208) 332-8507

Regardless of whether this virus is spreading from cow-to-cow, or is the result of direct exposure to infected birds (or their feces), we have a habit of underestimating HPAI.  Two weeks ago, the notion that HPAI would be infecting cattle and goats across 5 states would have been considered ludicrous.

So much so, that it apparently took several weeks into the investigation of sick cows in Texas before they decided to test for the virus (see Lisa Schnirring's CIDRAP article Avian flu detections in dairy cows raise more key questions).

If HPAI has been infecting (and possibly spreading) in cows undetected for months, it begs the question, what other reservoirs are we overlooking? 

Pigs obviously rank high on our list (see Netherlands: Zoonoses Experts Council (DB-Z) Risk Assessment & Warning of Swine As `Mixing Vessels' For Avian Flu), and with the summer & fall county and state fair season soon to begin, may require additional scrutiny. 

Last summer, in Avian Flu's New Normal: When the Extraordinary Becomes Ordinary, I wrote how outbreaks and spillovers that were nearly unthinkable two or three years ago have now become `the new normal'.

While it remains unknown whether avian H5 viruses will ever adapt well enough to humans to spark a pandemic, they continue to exceed our expectations. 

 

Mexico Reports HPAI H5N2 For the 1st Time in Nearly 30 Years

Credit Wikipedia

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Long before the emergence of the Asian lineage of the HPAI H5N1 virus in Guangdong Province in the mid-1990s, both LPAI (Low path avian influenza) and HPAI (High path) H5 viruses circulated in wild birds and poultry around the globe.   

The earliest known HPAI H5 virus was A/chicken/Scotland/59 (H5N1), which killed two flocks of chickens in Scotland in 1959. China's H5N1 virus rose to fame because it was the first HPAI H5 virus known to infect and sicken humans. 

During the 1980s and 1990s, a North American lineage of LPAI and HPAI H5N2 infected poultry flocks in the United States, Mexico, and the Dominican Republic.  The USDA cites two major outbreaks:

• The 1983-84 HPAI H5N2 outbreak resulted in humanely euthanizing approximately 17 million chickens, turkeys and guinea fowl in Pennsylvania and Virginia to contain and eradicate the disease.
•  In 2004, USDA confirmed an HPAI H5N2 outbreak in chickens in Texas. The disease was quickly eradicated thanks to close coordination and cooperation between USDA and State, local, and industry leaders.   

Mexico dealt primarily with LPAI H5N2 until the mid-1990s, when an outbreaks of HPAI H5N2 in Puebla, Mexico prompted the government to adopt poultry vaccination. Over the past 30 years, Mexico's LPAI H5N2 has reportedly diversified into 5 distinct clades (see Evolutionary Dynamics of Mexican Lineage H5N2 Avian Influenza Viruses). 

This week, for the first time since June of 1995, Mexico is reporting HPAI H5N2 on a non-commercial poultry farm with 117 free-range birds.  The WAHIS report states:

EPIDEMIOLOGICAL COMMENTS

The presence of highly pathogenic avian influenza (HPAI) virus subtype H5N2 was confirmed through PCR tests, virus isolation, genetic sequencing and intravenous pathogenicity index (IVPI) test, in the state of Michoacán, in a backyard farm. The premises have no contact with other poultry because no commercial poultry farm is implemented in the municipality. The sanitary situation of Mexico regarding this disease remains unchanged, since HPAI subtype H5N2 is not present in birds defined as "poultry" at the moment.

SENASICA is furthering its epidemiological investigation of the event and continues to urge poultry farmers to reinforce biosecurity measures on their farms and to immediately notify any anomaly observed in their animals, in order to protect national poultry production. The active epidemiological surveillance program is being maintained in technified production units, backyards, federally inspected slaughterhouses and municipal slaughterhouses as well as the monitoring of wild birds at national level.

Mexico's SENASICA reports:

Highly pathogenic AH5N2 avian influenza registered in a backyard unit in Michoacán

This epidemiological event does not represent a risk to human health, since the virus is exclusive to birds, nor does it affect the supply of chicken and eggs for the country.

National Agri-Food Health, Safety and Quality Service | March 27, 2024 | Release

The General Directorate of Animal Health of Senasica highlighted that commercial poultry farming is not involved.


The National Agri-Food Health, Safety and Quality Service (Senasica) confirmed the presence of highly pathogenic avian influenza (HPAI) AH5N2 in a free-range family production unit in Huetamo, Michoacán.

The General Directorate of Animal Health (DGSA) of Senasica highlighted that commercial poultry farming is not involved, explaining that the virus was detected in an isolated area and there are no commercial poultry farms registered in at least 100 kilometers around, therefore that the outbreak does not compromise the animal health status of our country.

This epidemiological event does not represent a risk to human health, since the virus is exclusive to birds, nor does it affect the supply of chicken and eggs for the entire country, which is why an increase in the prices of these poultry products is not seen. .

The agency of the Ministry of Agriculture and Rural Development reported that doctors from the Directorate of the Mexico-United States Commission for the Prevention of Foot and Mouth Disease and other Exotic Animal Diseases (CPA) of the DGSA began the investigation after A veterinarian reported high mortality on a farm that raised birds for self-consumption, in which, of a total of 120 birds, 117 had died at the time of the report.

Given the discovery, the DGSA immediately ordered the backyard unit to be quarantined and the CPA doctors applied the necessary counter-epidemic measures to deactivate the outbreak, such as cleaning, disinfection and establishing a sanitary vacuum period.

The first molecular biology RT-PCR results issued by official laboratories confirmed the presence of an H5 avian influenza virus, subsequently, through specialized tests, including viral isolation, primary genomic sequencing and the intravenous pathogenicity index. , it was confirmed that it was a highly pathogenic H5N2 avian influenza virus.

Agriculture's specialists in animal health emergency care carry out the corresponding investigations in the area to determine the origin of the infection. The activities carried out in the field are perifocal tracking in the surrounding properties and promotion of notification. Additionally, monitoring of wild birds found near the affected site was implemented in order to determine the source of contagion.

At this time, the official DGSA laboratories are carrying out deep genetic sequencing studies with the purpose of determining the possible origin of the virus.

Senasica urged poultry producers throughout the country not to let their guard down and strengthen biosafety measures in their poultry production units, both family and commercial, with the purpose of mitigating the risk of infections in domestic birds.

The highly pathogenic AH5N2 virus was identified in Mexico in commercial flocks in 1994 and was eradicated in 1995. Since then, our country has remained free of this highly pathogenic agent.

Any person who produces, processes, handles, moves or markets birds must immediately report to the health authority any abnormal behavior in their flocks, unusual mortality or any other suspicion of this disease to the telephone number 800 751 2100, or from their mobile phone through of the “AVISE” app, available for Android devices.

It isn't clear whether this H5N2 virus is a reassortment of HPAI H5N1 clade 2.3.4.4b, or a new incarnation caused by the spontaneous mutation of an LPAI H5 virus into an HPAI (see graphic below).

The fact that it was detected in a small, non-commercial flock, in a relatively remote region of Mexico may help contain this incident.  But given HPAI H5's tendency to overachieve, it's worth our keeping an eye on.

WAHIS Report On HPAI H5N1 Virus Detected In US Cattle

Credit https://comptroller.texas.gov/ 

#17,970

Information on the HPAI H5 infections in cattle in Texas and Kansas remains scant, but late yesterday the WOAH WAHIS dashboard carried the following brief preliminary epidemiological report on the virus.

EPIDEMIOLOGICAL COMMENTS

Highly pathogenic avian influenza (HPAI) H5N1 Eurasian lineage goose/Guangdong clade 2.3.4.4b was confirmed in samples from sick cattle collected from at least one dairy farm in Kansas and at least one dairy farm in Texas.

The initial sequences represent a sporadically detected 4 gene reassortant (B3.13 per GenoFlu) descended from the previously predominant genotype B3.2 first observed in wild birds in November 2023. No markers for mammalian adaptation nor antiviral resistance were observed.

This is an evolving situation - additional work and studies are in process. Federal and state agencies are moving quickly to conduct additional testing for HPAI, as well as viral genome sequencing, so that we can better understand the situation, including characterization of the HPAI strain or strains associated with these detections.

We've discussed often that we aren't dealing with a single H5N1 threat, but rather with an array of similar H5N1 viruses that are continually reassorting and evolving.  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 unique variants called genotypes. 

Genotypes are created when two flu viruses inhabit the same host, allowing them to reassort into a hybrid.  Even when we limit the field to a specific subtype (like H5N1), and a specific sub-clade (like 2.3.4.4b), there can still be dozens of genotypes due to reassortment.

Although this is rapidly changing situation, last fall researchers from several U.S. labs published a `snapshot' of H5N1's diversity in the United States in the months following its arrival in December of 2021, which found that the virus rapidly reassorted with local wild bird avian influenza viruses generating six major (and numerous minor) genotypes.

H5N1 highly pathogenic avian influenza clade 2.3.4.4b in wild and domestic birds: Introductions into the United States and reassortments, December 2021–April 2022

 Sungsu Youk a f, Mia Kim Torchetti b, Kristina Lantz b, Julianna B. Lenoch c, Mary Lea Killian b, Christina Leyson a, Sarah N. Bevins c, Krista Dilione c, Hon S. Ip d, David E. Stallknecht e, Rebecca L. Poulson e, David L. Suarez a, David E. Swayne a, Mary J. Pantin-Jackwood a

Abstract

Highly pathogenic avian influenza viruses (HPAIVs) of the A/goose/Guangdong/1/1996 lineage H5 clade 2.3.4.4b continue to have a devastating effect on domestic and wild birds. Full genome sequence analyses using 1369 H5N1 HPAIVs detected in the United States (U.S.) in wild birds, commercial poultry, and backyard flocks from December 2021 to April 2022, showed three phylogenetically distinct H5N1 virus introductions in the U.S. by wild birds.

Unreassorted Eurasian genotypes A1 and A2 entered the Northeast Atlantic states, whereas a genetically distinct A3 genotype was detected in Alaska. The A1 genotype spread westward via wild bird migration and reassorted with North American wild bird avian influenza viruses. Reassortments of up to five internal genes generated a total of 21 distinct clusters; of these, six genotypes represented 92% of the HPAIVs examined. By phylodynamic analyses, most detections in domestic birds were shown to be point-source transmissions from wild birds, with limited farm-to-farm spread.

While some genotypes fare better than others, new reassortants tend to cluster in different geographic regions.  Some may thrive and spread widely, while others may be less biologically `fit', and are unable to compete. 

Hopefully we'll get a more detailed analysis of this virus in the days ahead, along with a better idea of its spread in cattle, goats, and potentially other livestock.