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Bird flu spread to cows in the United States around New Year’s Eve, while the first sick cow was only tested in March. It is still not clear how big the outbreak is. Is the US government doing enough to prevent the spread? And is there sufficient insight into the virus?
There is a risk that the H5N1 virus will also reach cattle outside the US, the World Health Organization warned on Tuesday. When migratory birds pick up the virus from cows, it is spread further and cows in other countries can also become infectedsaid Wenqing Zhang, head of the WHO’s flu program.
The highly pathogenic bird flu variant H5N1 is now killing wild birds and mammals as far as Antarctica. The virus first appeared at the end of March in ruminants, on farms in Texas, Kansas and New Mexico. A mystery, according to virologists, and could cases have been missed elsewhere? Since then, the virus strain 2.3.4.4b has been available 36 companies in nine US states was found and one employee at a dairy farm in Texas was found to be carrying the virus. This person, who tested positive, only got red eyes.
Virologists are concerned about the US government’s lackluster approach. To fully understand how the virus spreads among ruminants, it must be closely monitored in animals, humans, meat, milk and in sewage. But so far there is little test data and what there is is only being released piecemeal. Source research is also difficult because access to farms is often hindered, the American virologist wrote Rick Bright this week on X. “As long as we do not know where and how the virus started, little can prevent it from happening again.” He said earlier for the time being no milk to drink.
American authorities are slowly starting to investigate measures to screw up. Since Monday, dairy cows are no longer allowed to be transported to other states without a negative test, unless they go to slaughter there. The United States Department of Agriculture (USDA) says all carcasses are inspected before processing, although that doesn’t mean they are all tested for bird flu.
In states where cows have tested positive, research has now been expanded to include minced meat – when milked cows go to slaughter, they usually end up as minced meat. Inspectors also take samples at slaughterhouses, but only if the animals come from farms where bird flu has already been tested.
Last week it turned out that the virus was in the lungs of a cow at a slaughterhouse, without the animal having had typical (bird) flu symptoms, such as lower milk production, less appetite, fever or abnormal manure. The milk from infected cows may be yellower, thicker and creamier than normal, but in cows that do not become ill from the virus, there is often nothing visible in the milk. This fuels fears that many more cows are carrying the virus without farmers or inspectors noticing.
The Ministry of Agriculture always gives two messages: American products are safe and we will test them. Although the ministry continues to emphasize that American milk and meat products are suitable for consumption, it is also investigating what happens to the virus when prepared at different temperatures.
Virus particles have been found in 20 percent of milk from American supermarkets
In a minced meat sample No virus particles have yet been found from thirty packages. It turned out that there was genetic material from the virus – not a live virus – in pasteurized milk. Virus particles have been found in 20 percent of milk from American supermarkets – almost three hundred samples from 38 states.
The American Food Safety Authority (FDA) was quick to announce that culture on eggs showed that there was no longer any live virus in the milk that tested positive. And laboratory technicians did not see it at all in baby milk (powder). In any case, the advice was to only drink pasteurized milk and not raw milk. Pasteurization – heating for some time minimum 63 degrees Celsius – should be enough to kill viruses.
Spread further
The question is whether all this will address the concerns of critics. Rather the opposite, as is evident from the reactions to the positive milk tests. If so much milk contains genetic material of the virus, the outbreak is likely to have spread further than can be deduced from the official figures. Another concern: underlying data that substantiate that the milk is safe is not available, the scientific journal wrote Science last week. Not everyone trusts that the usual method of pasteurization (15 or 20 seconds at 72 degrees Celsius) will kill all viruses.
The government is not only trying to protect citizens, but also the industry, a veterinarian concludes Sciencearticle. To prevent consumers from giving up milk and meat, fearing contamination. Colombia, which imports about six thousand tons of American beef annually, has been the first country to impose import restrictions on fresh and frozen beef from the infected states for two weeks.
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The authorities share too little data on all fronts, scientists believe, and that makes research and a good approach difficult, including internationally. So reported The New York Times that the ministry kept it under the radar for a long time that cows can infect each other and that the animals can also be infected without visible symptoms.
It is also difficult for the authorities to gain insight into this, because cows without symptoms have not been tested for a long time. Only late in April did it become known that farmers could also receive compensation for having cows without visible symptoms tested. And farmers are still not obliged to test, not even on cows with symptoms. Be at the same time in sewage measurements in Texas genetic traces of the bird flu virus were also detected. Another argument for broader testing.
In Arizona, scientists made it plausible that there are many more farms than the 36 companies that have now tested positive, and that the virus must have jumped to cows much earlier. On April 21, following continued complaints about lack of transparency, the Ministry of Agriculture released some snippets of raw virus genetic data.
Evolutionary biologist Michael Worobey of the University of Arizona made a genetic family tree from which he was able to draw striking conclusions: the virus must have already spread to cows in December or January, months before the first symptoms of the disease were noticed. This would mean that the virus is much more widespread than is currently known. “They already saw the thicker milk in February, it is a missed opportunity that was not tested weeks earlier,” Worobey told the BBC yesterday. “And data can be shared more quickly.”
A second conclusion, based on that limited data, is that the jump from bird to cow probably only took place once. That would be at least one reassurance, because it shows that the transfer to cows was a rare coincidence. It is also notable that the human infection appears to be different from that currently found in cows. That could be an old, extinct virus line.
Livestock transport can be an important cause of spread, it appears an analysis by USDA researchers, which also states that cows can be contagious for two or three weeks. In any case, the virus can jump in different ways: from bird to cow, cow to cow, cow to chicken, and in one proven case from cow to human. From the cats that drank raw milk from infected cows on a farm in Texas half died. Human-to-human transmission has not yet been observed in this outbreak of bird flu.
Because the virus is so clearly found in milk and udders, the assumption is that transmission of the virus occurs during milking, via contaminated equipment or through airborne droplets during cleaning – although this is all still speculation.
It is clear that migrant workers then run the greatest risk of infection. They have the most direct contact with the animals on large-scale American livestock farms, often with thousands of cows. But undocumented migrant workers will not report quickly to get tested. There would only be about 25 people tested are.
Human pandemic
It is not without reason that the concern is so great. With any mammalian infection, the virus can mutate and become more contagious. This increases the risk of a human pandemic developing. This risk is particularly high in pigs because bird flu and human viruses can mix in those animals. A more dangerous variant can also arise relatively easily in this way.
What makes a good risk assessment difficult in the US is that the exact origin of the virus found in humans is unknown. According to experts, this makes it difficult to say how representative the viruses known so far are for what else may be out there, possibly also among people.
The call on the government is therefore to test much more extensively, not only in cows, but also in pigs. And especially in states where there are no known cases of bird flu in dairy cattle. Although the White House has launched an ‘immediate response team’, there are also states, such as Indiana, that do not want to wait for federal measures and have already started testing themselves.
Wenqing Zhang, the WHO representative, also responded this week to criticism that US authorities are not transparent enough. The WHO regularly receives the latest status and also received the genetic code of the virus found at an early stage, she said. “We are sufficiently informed to prepare measures.”
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