A team of Kansas State researchers, including regents and university distinguished professor of diagnostic medicine and pathobiology Juergen Richt, found that bovine H5N1 influenza virus is primarily spread via milk, rather than through respiratory transmission.
“We wanted to do a nicely-controlled study to answer two important questions,” Richt said. “Is it a respiratory-transmitted pathogen and a milk-transmitted pathogen, or is the milk the major conduit of transmission? That was one question we answered.”
After collaborating with the Friedrich Loeffler Institute in Germany, Richt and his team found that overwhelmingly, avian influenza passes through consumption of infected raw milk. The team of researchers published their findings in the journal Nature.
“Milk-associated doesn’t mean it’s only the milking equipment,” Richt said. “It could be the milk in the milk parlor, it could be other things, milk contaminating feed, etc. There’s so many different ways it can happen. People get contaminated with the virus because they milk, and then they go from cow-to-cow and yada yada.”
Infected cattle will present with a lack of appetite and fever, Richt said.
“The most significant sign … is they [cows] have a significant drop in milk production, and the milk becomes — you cannot consume that milk,” Richt said. “It’s not very tasty. It’s not a good product.”
Richt said the spread of avian influenza through livestock has a significant economic effect.
“If you’re a dairy farmer you make money with milk, and if a cow who gave, say, 60 pounds of milk or more a day, or 80 pounds, suddenly only makes one pound, it’s in your wallet,” Richt said.
Outbreaks also have a direct impact on grocery prices, Richt said.
“This has not only impacted animal health and the economy of dairy,” Richt said. “This virus also affects poultry. Why do we have egg prices so high? Because of this virus. They’re the same virus. It’s highly pathogenic avian flu. It’s an avian virus which jumped into cattle.”
Richt said because of the volume of cows in most dairy farms, it is “almost impossible” to stop the spread of the virus once one is infected.
“We have farms with 100 thousand-plus animals,” Richt said. “They work 23 hours a day, so it’s almost impossible to protect against transmission from animal to animal because they cannot disinfect all the equipment every time they change and go from cow one to cow two. They can obviously clean but they cannot disinfect.”
Richt said the only way to stop the spread of infection is to switch to robotic milking, but only smaller farms can usually adopt this method.
“It’s about 150 to 200 thousand [dollars for] one milking robot, and each robot can milk 60, 70 cows,” Richt said. “If you have 100 thousand cows, how many robots do you need, and how much will that cost?”
However, Richt’s research will open up opportunities for vaccine development and more efficient virus testing in cows and other animals.
“We can think about ways to disinfect parlors, maybe develop fast tests so you identify positive animals and separate them and milk them in different parlors, not in your normal parlor,” Richt said. “… If you have influenza, you have to protect against respiratory disease, right? You need to make a vaccine which protects your lungs. In this case, we now know we have to make vaccines which protect against this mastitis, this inflammatory disease of the adult tissue.”
With over 60 cases found in humans over the past 11 months, Richt said researching avian influenza in cows is important because it gives scientists an opportunity to understand the disease and prevent spread between species.
“With this virus, we have one death out of about 65 or 70 infections, so people can get very sick,” Richt said. “… This is where veterinary medicine meets public health because we study zoonotic diseases in the animal species where it originates.”
