Tom Tabler
On July 8, a 1.8 M head table egg operation in Weld County, Colorado was confirmed positive with H5N1 avian influenza. Over the past weekend, Colorado announced that five workers involved in the culling of birds on this operation had tested positive for the virus. All five had mild symptoms – conjunctivitis (pink eye) and minor respiratory complaints. None required hospitalization. A sixth worker with mild symptoms was reported on Tuesday July 16. In addition, on Friday, Oklahoma became the 13th state with at least one infected dairy herd when it announced that a sample collected from a dairy herd in April had tested positive for bird flu. A second Oklahoma case was confirmed earlier today. As of today, the USDA has listed 157 dairy herds in 13 states as having tested positive for H5N1 since the outbreak was first confirmed in dairy cattle in late March. Table 1 lists states with H5N1-infected livestock herds as confirmed by USDA on July 15, 2024.
Table 1. States with confirmed cases of H5N1 in dairy cattle herds.
Despite attempts to contain the virus and despite summer’s heat which is baking much of the U.S., the H5N1 virus continues to stay one step ahead of efforts to control it. Poultry growers and dairy cattle farmers must remain vigilant and report anything that seems suspicious. We still do not have a clear picture on how widespread the outbreak is in dairy cattle and that hampers our ability to determine if the outbreak in cattle can be stopped and, if so, how best to do it if that goal is attainable. We know how hard the virus is to control in poultry flocks. We are approaching two and a half years for the current outbreak in poultry and we continue to see new cases on a regular basis. To date, 100 million birds have been affected and highly pathogenic avian influenza (HPAI) has been detected in a total of 1,165 flocks in 48 states. Of those, 506 flocks have been commercial, and 659 flocks have been backyard.
Unlike HPAI in poultry (which is a death sentence to the birds affected), thankfully, the condition is much milder in dairy cattle which show few respiratory symptoms and most fully recover in 10 days to two weeks, and do not require euthanization, as is the case with poultry. However, vigilance is required, along with good biosecurity, to limit the spread of the disease to the greatest extent possible. There is no doubt that the virus changed somewhat over the past winter. Even though the virus has been seen in poultry flocks since February 2022, it was not confirmed in dairy herds until March 2024. Viruses constantly change or mutate and something in the H5N1 virus changed in late 2023 or very early 2024, allowing the virus to more easily infect dairy cattle, which had not been the case before. We cannot prevent the virus from mutating, but we can practice good biosecurity year-round which is necessary to protect our flocks and herds.
In addition to common sense and good biosecurity, the Centers for Disease Control recommends that:
- People should avoid exposures to sick or dead animals, including wild birds, poultry, other domesticated birds, and other wild or domesticated animals (including cows), if possible.
- People should also avoid exposures to animal poop, bedding (litter), unpasteurized (“raw”) milk, or materials that have been touched by, or close to, birds or other animals with suspected or confirmed A(H5N1) virus, if possible.
- People should not drink raw milk. Pasteurization kills A(H5N1) viruses, and pasteurized milk is safe to drink.
- People who have job-related contact with infected or potentially infected birds or other animals should be aware of the risk of exposure to avian influenza viruses and should take proper precautions. People should wear appropriate and recommended personal protective equipment when exposed to an infected or potentially infected animal(s). CDC has recommendations for worker protection and use of personal protective equipment (PPE).
- CDC has interim recommendations for prevention, monitoring, and public health investigations of avian influenza A(H5N1) virus infections in people.
Following these recommendations is central to reducing a person’s risk and containing the overall public health risk. Do not expect the threat to lessen any time soon. While hot weather used to be somewhat of a deterrent to the virus, that is no longer the case. The virus has better adapted itself to hot weather and now the threat is ongoing throughout the year. That means biosecurity programs and increased vigilance must be ongoing throughout the year.
UT Animal Science/Extension continues to monitor the situation and is committed to supporting our stakeholders and clientele throughout this evolving event. As stewards of animal health and welfare across the livestock and poultry industries, our team of experts are constantly reviewing this changing and challenging situation and we will continue to provide updates as necessary.
