2023-04-21 13:43:02
Avian influenza viruses can be circulating for several months before they are discovered. This was shown by a genetic analysis of a bird flu outbreak in China between 2013 and 2017. Researchers therefore recommend continuous monitoring of the animals’ health.
“Our results underline that it is better not to wait until bird flu cases occur, because then the virus has probably been circulating longer,” said study leader Tanja Stadler in a statement from the Swiss Federal Institute of Technology Zurich (ETH Zurich) on Friday. Instead, according to the epidemiologist, health monitoring should be carried out in stables and live poultry markets at regular intervals.
The ETH researchers came to this conclusion by analyzing the bird flu strain H7N9, which was rampant in China between 2013 and 2017 and infected not only poultry but also humans. A total of 616 people in China have been shown to have died from infection with this subtype. The results were recently published in the journal “PNAS”.
The pedigree analyzes showed that the H7N9 virus must have been circulating in poultry for several months before it was discovered. The researchers were also able to show that significantly more poultry markets were affected than previously assumed. Outbreaks were difficult to detect, particularly in 2013-2016, when the virus was causing virtually no symptoms in poultry.
According to the researchers, the virus then changed and caused severe disease symptoms in poultry. This made it easier to identify affected chicken farms.
In 2017, the country began vaccinating poultry against the pathogen. Together with intensified hygiene measures in poultry markets, the authorities were able to weaken the epidemic in animals and greatly reduce transmission to humans. According to the experts, because the genome of viruses is constantly changing, there is still a certain risk that the H7N9 virus could become dangerous for humans again.
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