US health agencies launch new studies of H5N1 bird flu in dairy workers and dairy products

US health agencies are starting new rounds of tests on dairy workers and milk products to better understand the possible impact of H5N1 bird flu.

The US Centers for Disease Control and Prevention is partnering with the state of Michigan to begin a highly anticipated study to assess whether workers exposed to infected cattle had themselves become infected. And the US Food and Drug Administration is testing what’s known as flash pasteurization after recent studies raised questions about whether the method neutralizes all infectious virus in milk. The projects are part of a suite of new research announced by federal agencies on Tuesday to understand the dynamics of H5N1 bird flu, which for the first time jumped from birds to dairy cattle around the beginning of the year.  Since late March, more than 120 herds across 12 states have tested positive for the highly contagious infection, which appears to be spreading through contact with raw milk, the US Department of Agriculture confirmed. “We know this to be spread by contact with milk,” said Dr. Eric Deeble, who is the acting senior adviser for highly pathogenic avian influenza at the USDA.

Deeble said that early on, the movement of cattle was largely driving spread of the infection. But since the USDA ordered cattle to be tested before they could be moved state-to-state in late April, the infection has been ferried between farms on shared equipment and shared workers, according to a recent epidemiological study by the Michigan Department of Agriculture and Rural Development, or MDARD.

“We know that milk has really high viral loads, and so when we’re looking at transmission patterns, that’s a really high risk, it seems,” MDARD Director Dr. Tim Boring said.