In the United States, inspectors from the Veterinary Services and the Food & Drug Administration are investigating the dairy industry for possible H5N1 contamination. This research is carried out at several dozen dairy farms, as well as in supermarkets. Results are expected “in the coming days to weeks.”
The laboratory test would have already detected viral genetic material, even after pasteurization or heat treatment. What the researchers have found so far is causing concern among experts: one in five samples contained components of the bird flu virus A/H5N1.
The strange thing about the infected cows is that they do not have much virus in their throats, says Danish expert Lone Simonsen. On the other hand, their milk production is strange. It's very thick milk, and it's full of this virus. That's why there are warnings in the US that you shouldn't drink unpasteurized milk and milk products, says Lone Simonsen.
So far, two people have been infected in the US. This has already led to some countries in South America temporarily imposing import restrictions on American meat.
It is not yet clear how wild birds could have transmitted the virus to cows in the US. According to the Science Media Center, everything that happens in the US can be traced back to a single mention. This cow may have contaminated the milking machines and/or gloves of the farm employees through an infected udder.
This assumption is supported by the observation that the pathogen multiplies rapidly, especially in the udders – in contrast to the respiratory tract, where the pathogen could only be detected in small quantities.
But the high virus load in the udders causes other problems. “This means that not only is the virus spread with every drop of milk that enters the environment, but that the entire equipment needed for milk production can become contaminated with a contagious virus,” Schwemmle said in an interview with Die Welt. It is very difficult to control such a widespread infestation.