A highly contagious form of avian influenza continues to make its way through colonies of seabirds in the North Sea and the Northeast Atlantic. Meanwhile, it has also reached breeding grounds on the southwest coast of Ireland, Where observers find hundreds of dead or dying gannets and other species. Since the early summer of 2022, scientists and bird conservationists have been concerned about terns, gannets and other seabirds, tens of thousands of which have already perished – including on the German coast. Claire Teitelbaum of the US Geological Survey and her team have now identified a factor in mercury that can weaken the animals’ immune systems and make them more susceptible to the virus responsible. As mentioned in the Proceedings of the Royal Society b.
Migratory teals are suspected of spreading avian influenza pathogens: on the one hand, teals are a natural reservoir of the virus, and on the other hand, they can become infected in farmed poultry. They then transfer the spores on the train and infect other birds across the species. So Teitelbaum’s team tested 750 ducks from 11 species shot in San Francisco Bay to see if they had been exposed to bird flu and how much mercury they had.
In fact, an animal would have been five times more likely to have antibodies to bird flu if it had been contaminated with the liquid metal. In addition, the prevalence of avian influenza was higher in species that were also on average more mercury-contaminated. After all, none of the animals carried the highly pathogenic strain of H5N1 virus, which is circulating in Europe in 2022. Thus the results cannot be directly transferred to the situation in the North Sea and the North Atlantic.
However, mercury is known to weaken the immune system, thus increasing the likelihood of animals becoming infected with pathogens. The liquid metal is often ingested by birds and other organisms in the form of methylmercury, which is formed naturally through biomethylation and accumulates in the food chain. Mercury is introduced, for example, through mining or burning coal.
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