First avian influenza case in cattle: US authorities on alert

Avian influenza has been picked up for the first time in sick cattle, with US authorities identifying wild birds as source of infection.

US dairy cows exposed to wild birds have come down with highly pathogenic avian influenza, cutting milk production.

Highly pathogenic avian influenza has been detected for the first time in sick US dairy cows, as Australian authorities upgrade the risk of the virus reaching our shores.

The virus was picked up after USDA and state veterinarians launched an investigation into a mystery illness that led to decreased lactation, low appetite, and other symptoms among primarily older dairy cows in Texas, Kansas, and New Mexico.

“At this stage, there is no concern about the safety of the commercial milk supply or that this circumstance poses a risk to consumer health,” the USDA reported, as all milk is pasteurised.

As for the source of infection, US veterinarians are confident that “based on findings from Texas, the detections appear to have been introduced by wild birds”.

The detection of HPAI in dairy cows is only the second recorded incident globally of the virus infecting ruminants. The first occurred earlier this month in 10 young goats at a Minnesota farm, which had just cleaned up an HPAI outbreak in a poultry flock.

Five of the goats died, while the remainder were euthanised.

The outbreaks raise serious questions for Australian and New Zealand livestock producers, as to whether they need to tighten biosecurity on farms and feedlots where dairy and beef cattle share feed and pastures with wild birds.

An Australian Department of Agriculture, Fisheries and Forestry spokesman said it was actively tracking this issue.

“These are the first known detections in cattle and goats overseas,” the spokesman said. “Risk management measures such as pasteurisation are in place for all imported milk and dairy products including from the United States.”

However a Dairy Australia spokesman said: “It’s still too early to predict what implications it will have on international trade and Australian dairy products.

“The current outbreak is still in the early stages of investigation, and further monitoring and diagnostics are being undertaken to better understand the situation.”

Health authorities across the globe are on alert after HPAI first spread from Asia to Europe and then across the Atlantic to the Americas along bird migration routes in 2021, killing more than 500 million birds and infecting at least 26 mammalian species – from European dogs, cats and foxes to US and Asian bears and even South American seas lions and dolphins.

Chilean authorities recently detected the virus in the Antarctic, raising concerns migratory sea birds and marine mammals could soon carry HPAI to Australia and New Zealand.

Researchers with the Chilean Antarctic Institute have detected Highly Pathogenic Avian Influenza (H5N1) in Antarctica, raising concerns the virus could reach via seabird and marine mammal migrations to Australia and New Zealand.

The Weekly Times is aware Australia’s veterinary chiefs are in the midst of updating the risk assesment on HPAI, which up until now had assumed the likelihood of the disease reching Australia was low.

Back in the US, initial testing of infected cows’ unpasteurised milk and throat swabs, by the US National Veterinary Services Laboratories, found no changes to the virus that would make it more transmissible to humans.

The main concern is that the current variant of the virus H5N1 clade 2.3.4.4b - may evolve to become far more infectious among humans.

But since 2003, the World Health Organisation has recorded just 253 human HPAI cases across Cambodia, Loa, Viet Nam and China, of which 140 proved fatal.