A study published by the U.S. Centers for Disease Control and Prevention (CDC) has identified cases of H5N1 avian influenza among three veterinarians working with cows. This discovery was an important signal that the virus can spread among animals and humans without obvious signs of infection, which calls into question the effectiveness of existing viral disease surveillance systems. This was reported by Ars Technica, UNN wrote.
Details
According to the study, three veterinarians who work with cows have previously been diagnosed with H5 avian influenza.
The results may not seem surprising given the large-scale and ongoing outbreak of H5N1 among dairy farms in the United States, which has affected 968 herds in 16 states and resulted in 41 dairy farm workers becoming infected. However, it is noteworthy that none of the three veterinarians knew they were infected, and none of them had worked with cows that were infected or likely to be infected with H5N1. In fact, one of the veterinarians had only worked in Georgia and South Carolina, two states that had never reported cases of H5N1 infection in humans or dairy cows.
The study's findings suggest that the virus can spread silently among animals and humans, and that surveillance systems are missing cases of infection, both of which have long been concerns among health experts.
Egg prices in the US break records due to bird flu04.02.25, 18:28 • [views_27661]
"These results indicate the possible benefit of systematic surveillance to rapidly detect HPAI A(H5) virus in dairy cattle, milk, and people in contact with livestock to ensure proper risk assessment," the study authors, led by CDC scientists, concluded.
The study was conducted in September. Veterinarians were gathered at a face-to-face veterinary conference, where they donated blood samples and reported livestock exposures over the previous three months. A total of 150 livestock veterinarians participated in the study, 143 from the United States and seven from Canada.
Blood tests showed that three veterinarians, 2%, had antibodies to H5 influenza viruses, indicating recent infection. All three were from the United States (Canada has not detected bird flu in any cows). None of the three veterinarians reported any respiratory infection, flu-like symptoms, or conjunctivitis, which is a common symptom among documented H5N1 cases in dairy farm workers.
Since September, the U.S. Department of Agriculture has developed a national milk testing strategy to rapidly detect the avian influenza virus in large quantities of milk. The surveillance strategy has led to the recent discovery of a second case of H5N1 avian influenza spreading from wild birds to cows, affecting several herds in Nevada and at least one dairy worker.