Question Period Note: Highly Pathogenic Avian Influenza A (H5N1) in Dairy Cattle in the United States

• On March 25, 2024, the Canadian Food Inspection Agency (CFIA) was notified by the United States Department of Agriculture (USDA) of the detection of highly pathogenic avian influenza (HPAI) A(H5N1) in dairy cattle in Kansas and Texas.
• On April 1st, 2024, the US Centers for Disease Control (CDC) confirmed that an individual in Texas tested positive for HPAI A(H5N1) and had exposure to dairy cattle presumed to be infected with HPAI A(H5N1). This likely represents the first mammal-to-human transmission.
• On May 22, 2024, the CDC confirmed a second human case associated with the current outbreak in a Michigan farmworker who had regular exposure to dairy cattle infected with HPAI A(H5N1).
• CFIA has not detected HPAI A(H5N1) in cattle or other livestock in Canada, and there have been no human cases in Canada associated with the current global HPAI A(H5N1) outbreak.
• Based on current scientific evidence, PHAC’s updated risk assessment states that the risk of avian influenza infection to the general public continues to be very low.

• The Government of Canada, including the Canadian Food Inspection Agency, the Public Health Agency of Canada and Health Canada are taking a proactive approach to preparedness for Canada with animal and human health partners both domestically and internationally.
• Based on current scientific evidence, the risk of avian influenza infection to the general public remains very low.
• As of April 29, 2024, Canada requires testing for HPAI on all imported dairy cattle from the U.S. to ensure that sick cattle and products from sick cattle do not enter the food chain.
• In addition to the robust protective measures which already exist, the Government of Canada has conducted enhanced testing of Canadian milk at the retail level to assess the potential presence of HPAI A(H5N1) in Canadian dairy cattle. All 303 samples from across the country have tested negative for HPAI A(H5N1) viral fragments in milk.
• The Government of Canada, in collaboration with stakeholders, is enhancing surveillance by expanding testing of cattle in Canada to include voluntary testing of cows that are not presenting with clinical signs of HPAI.
• Federal preparedness actions span the continuum from monitoring and risk assessment, laboratory capacity, updated guidance and communications, science coordination, and medical countermeasure readiness.
• To date, Canada has not detected HPAI in Canadian cattle and there have been no domestically acquired cases among people in Canada.
• Canada uses a comprehensive integrated surveillance approach to detect and monitor cases in humans should they arise. Public health authorities are required to report confirmed and probable cases to PHAC within 24 hours.
IF PRESSED ON…

RISK TO HUMAN HEALTH
• Human infections with A(H5N1) are rare and are almost always acquired through direct contact with infected birds or exposure to heavily contaminated environments.
Through food/drink
• There is no evidence to suggest that eating thoroughly cooked food could transmit A(H5N1) to humans.
• Recent negative results of testing by USDA Food Safety and Inspection Service reaffirm that the US meat supply is safe.
• The latest information from the US Food and Drug Administration’s testing of A(H5N1) in milk samples shows pasteurization is effective in killing the virus.
• To date, retail milk samples tested from across Canada have been negative for HPAI A(H5N1) viral fragments.
• Pasteurized cow’s milk remains safe to drink. Pasteurization is a requirement for sale of cow’s milk in Canada.
• Drinking raw or unpasteurized milk comes with an increased risk of serious illness.
Through interaction with animals
• To help prevent the risk of transmission of avian influenza, people should avoid contact with sick or dead wild birds and other wildlife. Canadians are encouraged to visit the canada.ca website for additional information.
• People who are in close contact with infected birds or mammals and their environments (such as farmers, veterinarians, hunters, and wildlife workers) should take precautions to avoid getting sick including:
- wearing appropriate personal protective equipment.
- practicing good hand hygiene; and
- following recommended biosecurity practices.
• The Public Health Agency has partnered with the Canadian Centre for Occupational Health and Safety on advice on how to protect against avian influenza at work and is developing further resources. Canadians are encouraged to visit their website for additional information.
• Additional information on human health and avian influenza is available on a dedicated website on Canada.ca.
IF PRESSED ON REGULATORY ROLE, LAB CAPACITY, ANTIVIRAL TREATMENT AND VACCINES
Regulatory Role
H5N1 is classified as a risk group 3 human pathogen and a risk group 3 animal pathogen and is therefore regulated by both the Public Health Agency of Canada and the Canadian Food Inspection Agency in Canada.
· The Public Health Agency of Canada regulates facilities working with H5N1 under the Human Pathogens and Toxins Act and Regulations. H5N1 is a Security Sensitive Biological Agent, which means that it has the potential to be weaponized.
· The Canadian Food Inspection Agency regulates H5N1 under the Health of Animals Act and Regulations. It is considered a non-indigenous pathogen, which requires enhanced control measures to prevent the introduction of the pathogen into domestic animal populations.
· No new laboratories seeking to work with H5N1 can come online without approval from both the Public Health Agency of Canada and the Canadian Food Inspection Agency; it is two distinct authorizations.
· There are currently 8 facilities licensed by the Public Health Agency for work with avian influenza (H5). Of these, 6 facilities are dually authorized, meaning they are also authorized by the Food Inspection Agency to work with H5N1.
· Simple human diagnostic testing with primary specimens is exempt from the license requirement, provided that: the pathogen is in the environment and is naturally occurring; and the pathogen has not been cultivated.

Lab capacity
• Canada’s laboratory surveillance network between the federal, provincial, and territorial governments is prepared to deal with emerging infectious diseases, including A(H5N1). This network has the capacity to test thousands of samples per day.
• Canadian academics are conducting wastewater monitoring for A(H5), however, the reliability of A(H5) detection in wastewater has not been validated. One significant limitation is the inability to differentiate the source of positive wastewater samples (i.e., from wildlife, human or livestock/poultry sources) making it challenging to accurately interpret results.
• Canada is working in collaboration with the Canadian Public Health Laboratory Network (CPHLN) to ensure adherence to biosecurity and regulatory measures across laboratory facilities working with A(H5N1), including those involved in diagnostic activities. Canada is working to develop an advisory to assist diagnostic labs in the handling of specimens that may contain or are suspected to contain A(H5N1).

Influenza Antivirals
• Circulating strains of A(H5N1) remain susceptible to antiviral treatments.
• The Government of Canada, as well as provincial and territorial governments maintain stockpiles of antivirals to help ensure equitable pan-Canadian access to a secure, government-controlled supply.
Pandemic Influenza Vaccines
• Vaccination for humans against A(H5N1) is not recommended at this time but the Government of Canada will continue to work with international counterparts and manufacturers to monitor research and development of candidate A(H5N1) vaccines.
• In the unlikely event that avian influenza leads to a human outbreak or pandemic, PHAC could exercise options in its pandemic influenza vaccine (PIV) readiness contracts to order PIV targeting the avian influenza strain of concern.

Historically, highly pathogenic avian influenza (HPAI) A(H5N1) affecting birds and other animals has been most prevalent in areas of Asia and Africa; however, it has recently spread throughout Europe and the Americas, and most recently into wildlife in Antarctica. Since 2022, the virus has become widespread through migration of wild birds and has affected many different wild species and many poultry farms globally since then.

Since December 20, 2021, HPAI A(H5N1) has been detected in wild birds in all provinces and territories in Canada. Additionally, since February 2022, the Canadian Food Inspection Agency (CFIA) has reported cases of HPAI A(H5N1) in domestic bird flocks in 9 provinces (Newfoundland and Labrador, Nova Scotia, New Brunswick, Quebec, Ontario, Manitoba, Saskatchewan, Alberta, and British Columbia). Since April 2022, HPAI A(H5N1) has also been detected in wild mammals such as foxes, skunks, raccoons, seals, wild mink and bears from all provinces and one territory, and in domestic mammals (e.g., dog, several cats) from two provinces. To date, HPAI A(H5N1) has been detected in 422 premises in Canada since the start of this outbreak in late 2021, and more than 11 million commercial and backyard birds have been impacted.

HPAI A(H5N1) has also been detected in domestic cats in Poland, South Korea and the US (as well as those mentioned above in Canada), farmed fur animals in Finland, marine mammals in several countries, and most recently in livestock (e.g., goats and cattle) in the US. These detections in mammals are concerning as influenza viruses can easily change, and the Government of Canada is closely monitoring the situation for signals of increased adaptation to mammals or evidence of increased risk for human-to-human transmission.

Detections of HPAI A(H5N1) in wild and domestic mammals are not unexpected given some of these species are known to eat or be exposed to wild birds or live in environments that may be heavily contaminated with avian influenza viruses. However, there appears to be an increase in the number of reported mammal detections in Canada and globally compared to previous avian influenza outbreaks, likely due to the prolonged duration and extensive geographic spread of the current HPAI A(H5N1) outbreak. Current scientific evidence suggests the risk of a human contracting avian influenza from a domestic or wild mammal is very low, however, people in close contact with infected animals (such as farmers, veterinarians, hunters, and wildlife workers) are at increased risk of exposure and infection and should take precautions.

Avian influenza detection in dairy cattle is unusual and unexpected. The USDA and the CDC have confirmed that the avian influenza in the dairy cattle is the same strain that is currently circulating in the Pacific Flyway (i.e., HPAI A(H5N1) clade 2.3.4.4b). The USDA and CFIA believe farm-to-farm transmission is likely due to the movement of animals between farms (including poultry and dairy). With these recent HPAI A(H5N1) detections in 63 herds of dairy cattle in nine states (as of May 24, 2024), as well as the detection of viral fragments (RNA) in commercial pasteurized milk samples in the United States, further research and information is required on whether HPAI A(H5N1) can be transmitted through consumption of unpasteurized (raw) milk and products (such as cheese) made from raw milk from infected cows.

For the general population in Canada, PHAC has assessed that the current likelihood of human infection with HPAI A(H5N1) acquired from livestock is very low; the likelihood of infection for people with higher levels of exposure to infectious livestock is at most low.

As a general precaution, members of the public should not handle live or dead wild birds or other wildlife. Specific wildlife handling guidelines for hunters, wildlife rehabilitators, aviculturists and bird banders are available on Canada.ca. In July 2023, PHAC updated its Guidance on human health issues related to avian influenza in Canada (HHAI) to provide recommendations for public health authorities at all levels of government, as well as other partners and stakeholders involved in the shared responsibility and management of actual and potential human health issues related to avian influenza outbreaks, with an overall goal of successful response and containment.

PHAC is taking a proactive One Health approach to preparedness by engaging with the CFIA, Health Canada, ECCC and other federal and international partners, has led a HPAI A(H5N1) scenario planning activity to clarify roles and responsibilities and identify gaps and areas of collaboration in the event of sustained human transmission. Planning can be leveraged for all HPAI A(H5N1) events and other respiratory infectious diseases.

The annual seasonal influenza vaccine ("flu shot") does not provide protection against avian influenza. However, getting a seasonal flu shot each year can help reduce the spread of human influenza viruses between people and between people and animals.

Initial Discovery
• The outbreak was discovered through an investigation by the USDA, US Food and Drug Administration (FDA), and US CDC into an illness primarily affecting dairy cows in several states in March 2024.
• The detection of dead wild birds and cats on affected premises prompted testing for HPAI A(H5N1) after other more common illnesses in dairy cattle were ruled out. Initially, unpasteurized samples of milk collected from two dairy farms in Kansas and one in Texas, as well as a throat swab from a cow on another dairy farm in Texas, tested positive for HPAI A(H5N1). Further testing was pursued in other herds based on clinical presentation and connection to states with infected herds.

Human Health Risk (US)
• The first confirmed human case of A(H5N1) related to the outbreak in dairy cattle was a dairy worker in Texas who developed mild symptoms and recovered. The patient self-isolated and was treated with an influenza antiviral drug (oseltamivir). CDC indicated that they are not aware of any of the individual’s close contacts having experienced any symptoms. There is no sign of person-to-person spread of this virus at this time.
• On May 22, 2024, the Michigan Department of Health and Human Services (MDHHS) and US CDC announced another human case of influenza A (H5) virus identified in a Michigan farmworker who had regular exposure to dairy cattle infected with avian influenza A (H5N1). This person, diagnosed with influenza A (H5), had mild eye symptoms and has since recovered. Evidence to date suggests this is an isolated infection, with no signs of ongoing spread.
• CDC has indicated that least 300 people have been monitored due to exposure to infected or potentially infected animals; of the 37 tested for novel influenza A, to date, two human cases of avian influenza A(H5N1) have been identified.
• The CDC considers the human health risk to the general public from A(H5N1) to be low.
• CDC is working with state health departments to monitor workers who may have been in contact with infected or potentially infected animals and are testing those who develop symptoms.
• Based on current scientific evidence, PHAC’s updated risk assessment states that the risk of avian influenza infection to the general public continues to be low.
• Food safety concerns remain focused on consumption of raw milk. While testing can detect viral fragments from destroyed virus in pasteurized milk, the milk is rendered safe through pasteurization. From FDA testing to date, live virus has not been recovered from pasteurized milk samples, and FDA experiments have demonstrated the effectiveness of pasteurization in inactivating HPAI A(H5N1). Therefore, food safety concerns remain focused on consumption of raw milk.
• CFIA has tested 303 retail milk samples from across Canada, all of which have come back negative for HPAI viral fragments.

Dairy Cattle Health
• As of May 24, 2024, USDA has confirmed 63 detections of HPAI A(H5N1) in dairy herds across several US states: Texas (14), Kansas (4), Michigan (19), New Mexico (8), Idaho (8), Ohio (1), North Carolina (1), South Dakota (4), and Colorado (4).
• This is the second confirmed event of HPAI A(H5N1) involving livestock in the US, following a detection in kid goats in Minnesota in March 2024.
• Influenza A (including avian influenza) rarely infects livestock, including cattle and goats; avian influenza has not previously been reported in cattle in the US. Given the number of states and herds with positive HPAI A(H5N1) detections, cow-to-cow transmission cannot be ruled out.
• The possible route(s) of transmission and source(s) of exposure for the human case and cattle herds remain under investigation.
• US federal and state agencies are conducting further testing for HPAI A(H5N1), as well as viral genome sequencing, to better understand the situation and the HPAI A(H5N1) strain(s) involved.
• Testing by the US National Veterinary Services Laboratories has not found changes to the virus that would make it more transmissible to humans, which would indicate that the current risk to the public remains low.

Health Portfolio Actions
• The Government of Canada, in collaboration with stakeholders, is expanding its surveillance to manage the possible emergence of HPAI A(H5N1) in Canada by:
- requiring negative HPAI A(H5N1) test results for lactating dairy cattle being imported from the United States to Canada;
- conducting enhanced testing of milk at the retail level to determine the presence of HPAI A(H5N1) viral fragments in commercial milk. The results have been shared on canada.ca; and
- facilitating the voluntary testing of cows that are not presenting with clinical signs of HPAI A(H5N1) to facilitate enhanced industry biosecurity efforts.
• Should HPAI A(H5N1) be detected in Canadian cattle, the CFIA will work in close collaboration with the Public Health Agency of Canada, Health Canada, provinces, territories and industry, providing testing support through the Canadian Animal Health Surveillance Network (CAHSN).
• The Public Health Agency of Canada (PHAC) is taking a comprehensive, integrated surveillance approach to A(H5N1), including leveraging its pre-existing surveillance mechanisms which include:
o monitoring influenza activity using multiple components to detect and monitor A(H5N1) cases in humans should they arise (e.g., syndromic surveillance (FluWatchers), laboratory testing (typing), hospitalization data, (outbreak reporting);
o utilizing recently developed national case definitions to support provincial and territorial public health authorities’ reporting of confirmed and probable human cases of A(H5N1) to PHAC within 24 hours. Confirmed cases of A(H5N1) are notifiable under the International Health Regulations (2005); and
o Global Public Health Intelligence Network (GPHIN) monitors public information sources to detect and communicate information about potential public health threats worldwide – including A(H5N1) cases in humans and animals.
· PHAC is also working with key federal, provincial, territorial, local public health and academic partners to establish protocols for enhanced active human surveillance and studies of individuals highly exposed to animals that may have HPAI that could complement existing integrated influenza surveillance.
· With Canadian retail milk samples having tested negative for HPAI viral fragments, PHAC continues to work with CFIA and Health Canada to inform potential future milk testing to support early detection of A(H5N1) in cattle and the associated preparedness activities.