Ducks contaminated with mercury pollution to develop bird flu

July 22, 2023

Ducks exposed to mercury pollution are much more likely to contract bird flu, according to a study published Wednesday. This finding shows a different way in which man-made changes in the natural environment increase the risk of virus spread.

Outbreak of avian influenza

Bird flu rarely infects people, but repeated outbreaks in the US, the UK and other countries have resulted in millions of chickens being slaughtered this year.
It is believed that ducks and other wild waterfowl are the super-spreaders of the virus, also because they move over such long distances, possibly infecting other birds along the way.

Watch the ducks

Nearly 750 wild ducks of 11 different species were finished for the recent study in the Bay of San Francisco, California, along a migration route from Alaska to Patagonia.

The ducks were then tested to see if they had been exposed to mercury and if they had bird flu or antibodies to the virus in their system.

The results, published in the journal proceedings of the Royal Society B, showed that ducks exposed to mercury contamination had a 3.5 times higher probability of contracting bird flu in the previous year.

Claire Teitelbaum, a quantitative ecologist at the USGS Eastern Ecological Science Center and lead author of the study, said that mercury toxicity “can weaken the immune system and make infection with anything-including flu- more likely.”

In addition, she told AFP, the San Francisco Bay is “an important hotspot for mercury pollution in North America… mainly from the previous gold mining, when mercury was used in this process.”

Particularly infectious strain

However, the highly virulent bird flu virus H5N1, which is found in several regions of the world, has not been detected in ducks.

With many wild birds nesting in the north, Teitelbaum said outbreaks of bird flu in the U.S. had declined over the summer.

But she warned: “We’ll probably see a lot more action when they come back down.”

The epidemic comes as scientists are sounding the alarm that viruses are spreading from animals to humans due to climate change, deforestation, livestock breeding and other man-made causes.

There are “so many ways in which people have historically influenced and continue to change the natural world,” says Teitelbaum.

“Just another link that we need to add to our broader understanding of what is going on in the world,” she added, referring to the impact of pollution and contamination on the risk of issue spread.

Extremely Useful Study

The work was praised as “extraordinary” by Daniel Becker, a biologist from the University of Oklahoma, who was not involved in it.

Especially for viruses that could infect humans, such as bird flu, he added: “there are surprisingly few studies on pollutant concentrations in animals and their relationship with infectious issues.”

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