2024-07-08 16:23:43
Dhe rural veterinarian is an important human resource in the United States. Especially in the middle of the country, the stream from Idaho to Texas is also called Cattle Country. There are large farms of livestock, often with more than 10,000 animals per farm. A major specialty of veterinary medicine has been established there: dairy veterinarians. They specialize in diseases of large herds, and they play an important role in ensuring milk safety.
Since the end of March, however, since bird flu has been present in flocks, experts have been in a dilemma: according to the guidelines of the US Department of Agriculture, they should test a large number of animals for the virus influenza A / H5N1. ; to contain its spread and prevent it from spreading to humans. If scientists have their way, veterinarians will also take blood samples in which viruses can be detected; in order to understand the exact extent of the spread.
However, a significant number of farmers seem to be resisting the controls. That’s how it is in the industry”Mathematics” to read. Farmers fear their name, their meat and their money. But now the current study in the specialist magazine “Creation“again how urgently we need such tests. It’s not just contaminated dairy equipment that makes it easy for germs: the virus can spread through the milk and infect other animals. And – more importantly – it is able to bind to human receptors to attack the cells of the upper respiratory tract. And also the European disease protection authority, “European Center for Disease Prevention and Control(ECDC) warned on Monday that the threat to human health should not be ignored.
The virus is spread by milk
Virologist Yoshihiro Kawaoka from us behind the current results University of Wisconsin-Madison – proven expert on bird disease. With his team, he researched practical questions: Can contaminated raw milk infect other animals? Can the virus be transmitted to babies through breast milk, and how have the viruses adapted to humans before?
To answer these questions, the scientists infected mice with the A/H5N1 virus. By giving test animals cow’s milk contaminated with it or rinsing their noses with A/H5N1 solution.
The results showed that the virus infects the entire body of the test animal within two weeks, especially the mammary glands. The search that other researchers have already made for livestock, by the way: on the suspicion of physicians.
In the next experiment, the scientists exposed female rats to their young exposed to the virus. After a few days, women pass the pathogens to their children: with their milk, not through the air. Because only their babies get sick, but not the other mother rats or their litters that are put in their cages for control.
The research team then tested on ferrets whether infection by droplet infection was possible. And further testing finally showed that the virus circulating in the herds was able to bind to the so-called sialic acid receptor: This opened the door for the pathogen to enter the upper respiratory tract in humans.
It is these experiments in particular that both biologists and epidemiologists are interested in. The results help “to better assess the general virulence potential of H5N1 in infected cows on dairy farms,” said Stephan Ludwig, director of the Institute of Virology at the University of Münster, to the Media Center. And the results left him with mixed feelings.
On the one hand, it shows that infected ferrets only transmit the virus to other members of their species in a moderate to poor manner. Ferret experiments, explains Martin Schwemmle, director of the research group at the Institute of Virology, are very important in order to be able to assess the risk of possible transmission from person to person. Because “airborne viruses that are compatible with humans are very easily transmitted between fats,” the types of pathogens that are prevalent in birds are unlikely. The fact that ferrets are mostly healthy is a relief to biologists.
On the other hand, it was shown that the proteins are able to bind to the receptor found on the cells of the upper respiratory tract in humans. This will create a situation for viruses to spread again between people. And one in four people who have been infected so far while working on the cattle farm also have symptoms; The other three developed conjunctivitis.
A veterinarian discovers the first infection in humans
The fact that we discovered that people can still be infected is thanks to the experience of veterinary medicine. It was the vet who sent a farm worker with conjunctivitis to the doctor – and for testing. This is how the first case of H5N1 transmission from cattle to humans became known.
And veteran epidemiologist Jason Lombard, who previously worked for the US Department of Agriculture and now conducts research at Colorado State University, was able to provide another important piece of evidence. Together with colleagues at the University of Michigan, he was able to discover that the origin of the disease among cattle was not an isolated case: the virus attacked the herd several times and spread to twelve US states.
Due to the lack of cooperation of the farmers with the authorities, health services have been turned to veterinarians – precisely to keep an eye on human issues. “We have tried to work with the dairy unions in Texas, but the dairies have refused public health access to the facilities,” said a spokesman for the state health department.
However, it is unclear to what extent the results of current laboratory tests can be transferred to real situations. Experts such as Martin Beer, head of the Institute for Viral Diagnostics (IVD) at the Friedrich Loeffler Institute on the island of Riems, also assess the risk to humans as low. ECDC Director, Pamela Rendi-Wagner, also said: “As we continue to progress the epidemic situation in EU countries and around the world, there is reason for attention, but not enough concern. more.”
In the recently updated summer surveillance guidelines, the ECDC recommends establishing a floor for human testing for avian influenza. Surveillance methods have also increased: for example, in the preparation of hospitals to identify and detect zoonotic viruses, ie viruses that are transmitted by animals. A statement also states that the ECDC also offers EU-wide central testing for human samples known or suspected to have an avian influenza virus.
#Bird #disease #Farmers #test #cows #virus #spread #humans