In Texas, a person tested positive for the H5N1 bird flu virus after contact with suspected infected cows. His only symptom was red eyes and the patient was on the road to recovery, the US health authority CDC said on Monday. The affected person is receiving antiviral medication and has been instructed to isolate himself. He was infected with a so-called highly pathogenic virus variant that can make animals seriously ill.
Although the unspecified patient had direct contact with dairy cows, as the Texas Department of Health announced, it is still unclear whether he actually became infected from them. So far, people have mainly become infected from birds. However, several cases of infected cows have been reported in the US states of Texas, Kansas, New Mexico and Michigan since last week. They were probably infected from wild birds, the US Department of Agriculture said. It is still unclear whether the virus is also passed from cow to cow.
Epidemiologist Gregory Gray from the University of Texas considers cow infections to be worrying. He told the journal Science that it could be that this strain of bird flu has mutated in a way that could allow it to spread among cows and also infect people more easily. However, according to initial tests, the H5N1 viruses found did not show any corresponding adaptations, according to the Ministry of Agriculture.
The CDC emphasized that the current case in Texas does not change the risk assessment for the general public. The risk of infection remains low. Only people with close or long-term, unprotected contact with infected animals would be at higher risk of becoming infected.
According to the authority’s assessment, commercially available milk is also safe because it is pasteurized before it is sold. The treatment would inactivate pathogens, including flu viruses. The dairies are also obliged to only process milk from healthy animals for human consumption, it said. However, the CDC warned against drinking raw milk, for example on farms.
Human infections are rare
Avian flu has been spreading among birds to a previously unknown extent for just over two years. Since then, an increasing number of mammals have also become infected – including otters, foxes and sea lions. The fact that dairy cows are also affected is a new development.
Despite the massive epidemic among birds, infections with H5N1 among humans are comparatively rare. The person now affected in Texas is only the second person in the USA who has been proven to have been infected with this type of pathogen. The first case occurred in 2022, after direct contact with infected poultry. According to data from the World Health Organization (WHO), around 900 people worldwide have been infected with bird flu type H5N1 since 2003; A good half of them died from the virus.
In general, bird flu viruses are not well adapted to humans. A person has to inhale very large amounts of viruses to become infected. This usually only happens through very intensive contact with sick birds, for example on poultry farms. Since the virus affects the bronchi in humans, person-to-person transmission via the upper respiratory tract is almost non-existent.