Due to the spread of avian flu in American dairy herds, the Canadian government has expanded its surveillance program of testing. Lactating dairy cattle imported from the U.S. must now have negative tests. Additionally, voluntary testing will be available for cows not showing clinical signs of Highly Pathogenic Avian Influenza (HPAI) as part of enhanced industry biosecurity efforts. On Thursday, May 23rd, the Canadian Food Inspection Agency (CFIA) reported that 303 retail milk samples from across Canada were tested, and all of them came back negative for HPAI or HPAI fragments. Using a highly sensitive polymerase chain reaction (PCR) test that can detect fragments of the virus, even if the virus is not infectious, to test the milk, the agency found no evidence of the disease. According to the statement from the CFIA, “Negative results mean that HPAI fragments are not present in milk. This supports current reports that the virus has not been detected in Canadian dairy cows.”
Thirty-four dairy herds across nine states have been affected. The most probable initial source of infection is believed to be feed contaminated with feces from wild birds infected with the virus. The Texas panhandle region is situated in the Central Flyway for migratory birds, the main natural reservoir for avian influenza viruses. Although the exact source of the virus is unknown, the presumption that wild birds are the source of the outbreak is well-founded.
H5N1 has primarily affected birds. However, in the past two years, the virus has infected over 200 species of wild and farmed mammals, leading to severe symptoms and death in some cases. Recently, a group of alpacas on a farm in Idaho tested positive for H5N1 bird flu for the first time. The gene sequence of the viruses isolated from the alpacas identifies a close relation to the H5N1 viruses currently found in American dairy herds. The World Health Organization (WHO) still considers bird flu a low risk to humans. However, the scientific community is concerned that it could be moving closer to becoming a pathogen easily transmitted between people. While human cases have been reported sporadically around the globe, no person-to-person transmission has been reported.
The Vaccine and Infectious Disease Organization (VIDO) at the University of Saskatchewan has been studying avian flu since 2023. Yan Zhou, an expert in vaccine development at VIDO, has been focusing on influenza-type viruses for over 20 years and is currently working on H5N1, a highly pathogenic variant of bird flu. Zhou has developed a “virus-like” particle that can be used to create and stockpile a vaccine, in case H5N1 becomes a significant concern in humans.
Virologist Alyson Kelvin is also involved in VIDO’s H5N1 project. She initially joined VIDO to help develop a made-in-Canada vaccine against the COVID-19 virus. Kelvin mentioned that avian influenza is challenging to contain due to its transmission by migrating wild birds. North American migration routes have become overwhelmed with the virus, and an estimated 7.2 million birds in Canada are believed to be infected with H5N1, including about 500,000 in Saskatchewan.
A local dairy farmer who asked not to be named stated that while they have been watching for dead migratory birds they have not found any and referred to the research carried out by Agriculture and Agri-Food Canada in 2022. They sought to answer the question, could swallows spread avian influenza viruses (AIVs) through their feces in agricultural areas that contain domestic poultry facilities? Some species of swallows, particularly barn, tree, and cliff swallows, prefer nesting on open structures in agriculture regions, including barns, which house livestock. Fecal droppings were collected and tested from over 200 swallow nesting sites. All the samples tested, returned negative results for avian influenza viruses (AIV) which suggests that swallows are not a primary cause of AIV outbreaks and their presence around domestic poultry facilities would present a low risk of disease transmission. The CDC supports that finding in its statement that most backyard birds, like cardinals, robins, sparrows, blue jays, crows, and pigeons, do not usually carry the bird flu viruses dangerous to domestic poultry and people.
Using an enclosed free stall barn system with automated curtains that lift and lower controlling the temperature and comfort level for their cows, the cows do not come in contact with migratory waterfowl, the prime carriers of bird flu. Those two factors make this dairy farmer comfortable with their normal bio-security procedures. This method of housing dairy cattle is becoming more popular among dairy farmers as a more controlled environment benefits milk production.
Despite the virus not yet being detected in Canada, some scientists are sampling wastewater to detect its emergence as early as possible. Wastewater tracking and surveillance proved important during the pandemic for understanding how viruses spread in real-time. The processes and procedures established to track the spread of COVID-19 also help predict other community outbreaks. Wastewater surveillance is important for monitoring highly pathogenic bacteria such as the avian influenza virus.
Scientists hope evidence of bird flu can be captured by the scientific procedures already in place to track and identify typical flu strains. They recommend the general public be cautious about handling any live or dead birds, and if it is unavoidable to protect themselves with proper masks, gloves, and handwashing.
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