Mass death of sea lions from bird flu suggests the virus may be jumping between mammals in the wild

Hundreds of dead or dying sea lions have washed up on the beaches of Peru since January.

The animals, majestic carnivores that can weigh up to 350 kilos, suffer agonizingly from convulsions and drowning before dying.

Nothing like this had ever been observed in the region.

A scientific team now confirms that the culprit of the outbreak is the jump of the A(H5N1) bird flu virus from seabirds to these wild mammals.

The researchers, Peruvian and Argentine, do not rule out a horrifying hypothesis: that the virus has

again to pass from mammal to mammal, as it apparently did in a Spanish mink farm.

It would be the first time this has occurred in nature.

The main theory of these scientists is that the 634 dead sea lions detected were infected one by one, independently, by living with sick birds or eating their corpses, according to the Argentine biologist Sergio Lambertucci, one of the leaders of the investigation.

The scientist, however, highlights a suspicious episode: on January 27, a hundred dead sea lions were suddenly found floating in the waters of Isla Asia, less than 100 kilometers south of Lima.

“It wouldn't be strange if a few of them had eaten infected birds, but all of them?” asks the scientist, from the Biodiversity and Environment Research Institute, in the Argentine city of San Carlos de Bariloche.

Dutch veterinarian Thijs Kuiken, an expert on emerging diseases, is skeptical of the hypothesis that each sea lion became infected on its own.

"Given the large number of specimens found dead, it seems more likely that there was direct transmission between sea lions," says Kuiken, from the Erasmus University Medical Center in Rotterdam.

"It's worrying," warns the vet.

“This is the second mass mortality episode to suggest that this virus can readily adapt to efficient mammal-to-mammal transmission.

If it happens in mink and sea lions, why won't it happen in humans? ”, He alerts.

SERNANP technicians collect samples from a dead sea lion in the Paracas National Reserve, on January 25.- (AFP)

The A(H5N1) virus that is circulating around the world is a subtype of highly pathogenic avian influenza.

In Europe it has caused the most devastating epidemic in history, with more than 50 million poultry slaughtered in just one year.

The virus reached South America in late 2022, wreaking havoc in Peru, where it has killed more than 50,000 wild birds, mostly pelicans and boobies, according to data from Peruvian and Argentine scientists.

The pathogen has jumped many times from bird to mammal, even to people in exceptional cases, but then it is not transmitted from mammal to mammal.

Scientists fear mutations that could cause a lethal pandemic in humans.

Thijs Kuiken believes there is another reason for concern.

“There are video footage showing people in Peru trying to rescue sea lions potentially infected with the virus.

Those close contacts increase the chances of transmission of the virus from sea lions to humans, ”he warns.

The Peruvian government has asked citizens not to approach wild animals.

On January 3, a 9-year-old girl from the Ecuadorian province of Bolívar was admitted to the intensive care unit in critical condition, after being in contact with poultry, and later had a favorable evolution, according to the World Health Organization. .

It was the first reported case of human infection by this avian influenza virus in Latin America.

The 634 dead sea lions have been found on various beaches and protected areas in Peru, such as the Paracas National Reserve.

The researchers have analyzed six specimens and have found the virus in all of them, but the autopsies of many others show the traces of bird flu: hemorrhagic pneumonia in the lungs and hemorrhagic encephalitis in the brain.

Sergio Lambertucci recalls that sea lions are very social animals, living in colonies, often overcrowded.

"If you have to think of wild species with more possibilities of transmission of the virus from mammal to mammal, it is in social animals such as sea lions, which live very close to each other," says Lambertucci.

Sea lions in the Paracas National Reserve, in Peru, on January 25.- (AFP)

The same team of Peruvian and Argentine scientists already warned on January 19 in the magazine

that the arrival of the bird flu virus threatened protected birds in South America, including the Andean condor.

The researchers have now decided to urgently publish the first draft of their study on sea lions, without waiting to complete it.

“We wanted to give the alert as soon as possible due to the worrying nature of the situation.

It is the first case of mass mortality of wild mammals in South America and could be the first event of intraspecies transmission in wild mammals in the world”, explains Lambertucci.

The Argentine biologist stresses that they will need weeks to carry out the essential genetic studies of the virus to confirm or rule out their hypotheses.

The Peruvian ornithologist Víctor Gamarra, co-author of the work, laments the slow reaction of the authorities.

“We published the letter in

precisely to draw the attention of Latin American governments to the need for follow-up, an epidemiological analysis, to see what other species were affected”, explains Gamarra, from the National University of San Agustín de Arequipa.

“There was an epidemiological silence, in which the public institutions here stated that everything was under control.

And suddenly these reports appeared of people finding dead sea lions all over the Peruvian coast.

That is when the institutions began to take some samples”, says the ornithologist.

Among the Peruvian co-authors of the study are seven members of the National Service of Natural Areas Protected by the State.

In Spain last year there were 37 outbreaks of highly pathogenic avian influenza in poultry and another 138 cases in wild birds.

In one of the outbreaks, on a farm with 150,000 laying hens in Guadalajara, two workers became infected without developing symptoms.

In October, the virus entered a fur farm with 52,000 American mink in Carral (A Coruña), causing a mortality of more than 4% in just one week.

A study led by Montserrat Agüero, from the Ministry of Agriculture's Central Veterinary Laboratory, suggested that the avian virus mutated at the Galician facility and began to be transmitted from mammal to mammal.

The Spanish outbreak set off alarm bells around the world.

Even the British doctor Jeremy Farrar, newly appointed scientific director of the World Health Organization,

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