Risk of Bird Flu spreading to cows outside US, says WHO

World Health Organization (WHO) said on Tuesday there was a risk of H5N1 bird flu virus spreading to cows in other countries beyond the United States through migratory birds. United States officials are seeking to verify the safety of milk and meat after confirming the H5N1 virus in 34 dairy cattle herds in nine states since late March, and in one person in Texas. With the virus carried around the world by migratory birds, certainly there is a risk for cows in other countries to be getting infected.

The United Nations (UN) agency deems the overall public health risk posed by the virus to be low but urged vigilance. The UN had received regular updates and praised the United States transparency on the outbreak so far to share the bird flu virus genetic sequence early. The collaboration with United States Centers for Disease Control and Prevention (CDC) and the information the UN has received so far enables the UN to monitor the situation and to update the preparedness measures.

On March 16, cows on a Texas dairy farm began showing symptoms of a mysterious illness now known to be H5N1 bird flu. Their symptoms were nondescript, but their milk production dramatically dropped and turned thick and creamy yellow. The next day, cats on the farm that had consumed some of the raw milk from the sick cows also became ill. While the cows would go on to largely recover, the cats were not so lucky. The cats developed depressed mental states, stiff body movements, loss of coordination, circling, copious discharge from their eyes and noses, and blindness.

By March 20, over half of the farm’s 24 or so cats died from the bird flu.

In a study published today in the journal Emerging Infectious Diseases, veterinary researchers in Iowa, Texas, and Kansas found that the cats had H5N1 not just in their lungs but also in their brains, hearts, and eyes. The findings are similar to those seen in cats that were experimentally infected with H5N1, aka highly pathogenic avian influenza virus (HPAI). But, on the Texas dairy farm, they present an ominous warning of the potential for transmission of this dangerous and evolving virus.

The contaminated milk was the most likely source of the cat’s fatal infections, the study authors concluded. Although it can not be entirely ruled out that the cats got sick from eating infected wild birds, the milk they drank from the sick cows was brimming with virus particles, and genetic data shows almost exact matches between the cows, their milk, and the cats. Therefore, the findings suggest cross-species mammal-to-mammal transmission of HPAI H5N1 bird flu virus and raise new concerns regarding the potential for virus spread within mammal populations.

The early outbreak data from the Texas farm suggests the bird flu virus is getting better and better at jumping to mammals, and data from elsewhere shows the virus is spreading widely in its newest host. On March 25, the United States Department of Agriculture (USDA) confirmed the presence of H5N1 in a dairy herd in Texas, marking the first time H5N1 had ever been known to cross over to cows. Since then, the USDA has tallied infections in at least 34 herds in nine states: Texas, Kansas, Michigan, New Mexico, Idaho, Ohio, South Dakota, North Carolina, and Colorado.

The Food and Drug Administration (FDA), meanwhile, has detected genetic traces of H5N1 bird flu in roughly 20 percent of commercial milk samples.

While commercial milk is still considered safe—pasteurization is expected to destroy the virus and early testing by the FDA and other federal scientists confirms that expectation, the finding suggests yet wider spread of the virus among the country’s milk-producing cows.