Two weeks after the U.S. Department of Agriculture implemented mandatory testing and reporting for interstate movement of dairy cattle in response to the spread of bird flu within the nation’s livestock sector, there are still no confirmed cases of the H5N1 influenza virus in Illinois.
This is according to Illinois Department of Agriculture State Veterinarian Mark Ernst, who said dairy cattle producers were asked to implement safety protocols to prevent spreading the strain of highly pathogenic avian influenza [HPAI], whose presence has been detected in the nation’s milk supply.
“H5N1 was first detected in livestock in Texas. The thought is that they were exposed to perhaps wild birds, which were able to transmit it over to cattle,” said Ernst, a Washington, Illinois, native who has served as state veterinarian for about the last 20 years. “In Illinois, we have not had any detections so far in our dairy herd. There are nine other states that have had detections on 36 premises.”
There have been no confirmed U.S. detections of H5N1 in livestock reported since the USDA issued the mandatory testing and reporting protocol in late April, said Ernst, adding mortality rates among infected livestock have been low to non-existent.
“It seems the cows recover over a period of time, though it may take upwards of a month," said Ernst. "They do come back in their milk; however they don’t appear to be milking at a level where they were before they became infected."
Illinois milk producers have been stepping up their biosecurity measures and limiting farm visitors since the H5N1 outbreak gained momentum several weeks ago while monitoring for telltale signs of the virus in their cattle.
According to guidance issued to dairy cow producers on Tuesday, the USDA mandates that producers report animals with the following clinical signs to their state veterinarian immediately: decreased herd level milk production; acute sudden drop in production with some severely impacted cows experiencing thicker, concentrated, colostrum‐like milk; decrease in feed consumption and lethargy, dehydration and fever, among other symptoms.
However, some cattle may present asymptomatically yet still harbor the H5N1 virus.
“You’ve got to be really careful right now introducing new stock to the herd. It would be advisable to isolate incoming animals," said Ernst. "The other thing that applies to more than just H5N1 is good biosecurity. You’ve got to limit farm traffic to essential traffic, and have good disinfectant cleaning of equipment and buildings. You also must limit the access of wildlife to feed sources and water sources.”
Scientists are working to discover the pathway the virus takes in infecting cow milk. Reuters reports scientists suspect the virus can spread between cattle during the milking process, either through contact with infected equipment or with a virus that becomes aerosolized during cleaning procedures.
“For whatever reason, the virus has had an affinity, more or less, for the udder and for milk,” Ernst said. ‘Fortunately, pasteurization has shown so far to be effective at destroying the virus in milk. The consumption of pasteurized dairy products doesn’t seem to be a risk at all to the public.”
An IDOA news release noted the U.S. Food and Drug Administration has announced the commercial milk supply is believed safe due to the pasteurization process that destroys bacteria and viruses in milk. Protocols also are in place to destroy milk from affected dairy animals, according to Illinois Department of Public Health Director Dr. Sameer Vohra.
“IDPH prioritizes the safety of our milk supply as well as the Illinoisans who work with cattle and poultry,” said Vohra. “Please note that pasteurized milk is safe, but we strongly recommend that Illinoisans avoid any unpasteurized raw milk products at this time based on the potential risk of infection.”
The virus seems to be contained exclusively to dairy cattle at this point, Ernst observed. “At this point in time, there have been no reports of the virus in beef cattle. That could change; this is evolving and we’ve got to be vigilant.”
Though the risk to livestock and the nation’s milk and food supplies may be nominal, the Center for Disease Control reported on Wednesday that the first case of human H5N1 infection has been confirmed in a Texas dairy worker.
While the current public health risk is low, the CDC is watching the situation carefully and working with states to monitor people with animal exposure. In addition, the CDC is also beginning to monitor wastewater for signs of the virus and will issue a public report soon.
Illinois is home to more than 600 dairy farms with 73,000 cows or calves, according to the USDA National Agricultural Statistics Service.
