MSU researchers investigate influenza outbreak in US cattle amid rising transmission concerns

17 May 2024 --- New research from the US, where the dairy cattle industry faces mounting challenges over the spread of avian influenza, has begun investigating the effects of the highly pathogenic H5N1 outbreak on dairy cattle reproduction and milk production. It will also examine how to mitigate the transmission of the disease.

The Michigan State University-led project brings together veterinarian and dairy health epidemiologist experts specializing in transboundary infectious diseases in both livestock and wildlife animal populations.

The aim is to understand what’s happening in the country’s cattle sector, where H5N1 infections have been detected in dozens of dairy herds across Colorado, Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota and Texas.

The virus has also been identified in unpasteurized milk, as well as swabs and tissue samples from sick cattle.

“Immediately upon the onset of the H5N1 outbreak in Michigan dairy cattle, MSU AgBioResearch, the College of Veterinary Medicine and MDARD began conversations about research questions that, when answered, could inform policy and management strategies to help prevent transmission within and across dairy herds,” says James Averill, assistant director of MSU AgBioResearch and leader of the organization’s animal agriculture initiatives.

“This research will enable the dairy industry to better understand H5N1 and the impacts on dairy herds over time.”

The research will assess the short and long-term effects of the disease on reproduction and milk production in cattle.The USDA National Institute of Food and Agriculture (NIFA) and the Michigan Alliance for Animal Agriculture will support the project through capacity funding.

Filling in knowledge gaps
The research team will look into crucial issues about the avian influenza outbreak, including the short- and long-term effects of the disease on reproduction and milk production and assess the factors influencing the likelihood of herds becoming infected.

They will also try to identify what increases or decreases the likelihood of cows becoming infected and how the virus spreads within and between herds.

Annette O’Connor, co-lead of the project from the College of Veterinary Medicine’s Department of Large Animal Clinical Sciences, says there is “an enormous amount of information we don’t know.”

“This outbreak underscored the critical need to understand the dynamics, impact and prevention of H5N1 among the cattle population. We are fortunate to be able to ground this research in on-farm studies, working closely with MDARD to access farms that have had herds test positive for the virus.”

Farm studies
The team will carry out five studies on farms with H5N1-positive animals. They will collect blood, nasal swabs and milk samples from lactating cows and examine milking equipment for H5N1 presence.

The US government recently restricted the transportation of lactating cattle to contain the virus' spread.The USDA-approved MSU Veterinary Diagnostic Laboratory conducts the H5N1 testing.

Data from the Michigan farms will be combined with findings from other universities nationwide for a comprehensive analysis.

“We’re trying to understand how long animals are shedding the virus and how long the virus stays active,” O’Connor continues. “For example, if we were to find that cattle are often positive on nasal swabs, we might conclude that nose-to-nose contact is a common route of transmission. Likewise, we may see that some samples come back negative quite often and show that those routes are much less likely.”

“The overall goal is to equip our producers with the information needed to make informed decisions on how to best protect their cattle and by extension, animal safety more broadly.”

Earlier this week, the USDA revealed a series of measures to tackle the ongoing impact of avian flu (H5N1) in US dairy cattle. These included a cash injection of US$101 million for the prevention and treatment initiatives and up to US$28,000 per farm to enhance testing and biosecurity measures for curbing the virus’ spread.

By Gaynor Selby

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