BUENOS AIRES - Scores of sea lions have died from bird flu in Argentina, officials said on Tuesday, as an unprecedented global outbreak continues to infect mammals, raising fears it could spread more easily among humans.

Animal health authorities have recently reported dead sea lions in several locations along Argentina’s extensive Atlantic coast, from just south of the capital Buenos Aires to Santa Cruz near the southern tip of the continent.

Another “50 dead specimens have been counted… with symptoms compatible with avian influenza”, read a statement from a Patagonian environmental authority.

“The number of dead is rising. There is no veterinary treatment for these cases,” a local official told AFP on condition of anonymity.

The authorities have asked Argentinians to avoid beaches along the country’s roughly 5,000km coastline where cases have been reported.

Sea lions are marine mammals, like seals and walruses. Adult males can weigh about 300kg.

The H5N1 bird flu has typically been confined to seasonal outbreaks, but since 2021 cases have emerged year-round and across the globe and led to what experts say is the largest outbreak ever seen.

Hundreds of sea lions were reported dead in Peru earlier in 2023, as the virus ravaged bird populations across South America.

There is no treatment for bird flu, which spreads naturally between wild birds and can also infect domestic poultry.

Avian influenza viruses do not typically infect humans, although there have been rare cases.

But the outbreak has infected several mammalian species, such as farmed minks and cats, and the World Health Organisation (WHO) warned in July that this could help it adapt to infect humans more easily.

“Some mammals may act as mixing vessels for influenza viruses, leading to the emergence of new viruses that could be more harmful to animals and humans,” the WHO said in a statement. AFP