Bird flu moves south, devastating sea lions in Argentine Patagonia

In early August, about 20 sea lions were found dead off the coast of Tierra del Fuego, in the southernmost tip of Argentina. Analysis confirmed that seven of these marine mammals were infected with the highly pathogenic H5N1 avian influenza virus, or bird flu. Since then, the authorities have reported outbreaks in different provinces across the country. The virus has spread rapidly to the south of the continent ever since a case was detected in wild birds in Colombia in late 2022. Scientists are now studying the possible risks that could arise should it reach Antarctica.

The latest positive cases detected in Argentine sea lions were reported this past Monday. The authorities subsequently released a statement warning that “the alert remains in place.”

Samples were taken from mammals found dead in the cities of Claromecó and San Blas, in the province of Buenos Aires, as well as in the city of San Antonio Este, in the province of Río Negro. Before this, scientists identified cases on different beaches and protected areas in the provinces of Tierra del Fuego, Río Negro, Chubut and Buenos Aires.

“This outbreak in sea lions began in Peru, then it passed to Chile and now it’s reaching Argentina,” warns Pablo Plaza, a biologist and researcher at CONICET, the main organization dedicated to promoting scientific research in Argentina. The virus has affected, above all, the Otaria flavescens species — commonly known as the Patagonia sea lion — a brown carnivore that can weigh up to 800 pounds. “There are two hypotheses here,” Dr. Plaza explains: “Either they were infected because they were in contact with infected birds — which is the most likely [scenario] — or the virus, in some way, underwent a mutation and is now being transmitted from sea lion to sea lion.”

The bird flu currently circulating around the world — H5N1 — was derived from a pathogen first detected in geese raised in China, back in 1996. It’s a highly contagious subtype that has led to the unprecedented spread of the disease in birds. From Asia, it went to Africa and Europe — where more than 50 million poultry were slaughtered in a year to contain the outbreak — and, from there, it reached North America via Iceland, according to scientists. In October 2022, it was detected for the first time in wild birds in Colombia. It has now spread throughout South America.

From birds, the virus jumped to mammals. “When it reaches the fauna, it’s a problem, because you cannot easily handle wild animals,” Plaza emphasizes. In Peru and Chile — where the situation was especially serious — more than 15,000 infected sea lions died, according to the researcher’s data. Other estimates calculate that there were more than 20,000 deaths. “In the coming weeks, we’ll have more evidence of the real scope of this outbreak in Argentina,” the biologist notes.

The southernmost case of H5N1 in a sea lion was detected back in June, in Puerto Williams, Chile. A report published on August 23 by the OFFLU — the global network of animal influenza experts — notes that “there’s a substantial risk” that the spread “will continue southward and reach Antarctica and its offshore islands,” where the virus still isn’t present. “This risk may increase in the coming months, due to the spring migration of wild birds,” the report reads. It warns that the “negative impact” of the virus on the ecosystem “could be immense.”

“The whole world is on high alert with this virus,” Plaza explains. A team of Peruvian and Argentine scientists, including Plaza, warned this past January that the arrival of the bird flu virus on the continent threatened protected birds in South America. With the mass death of sea lions, the same team published the first draft of research suggesting the possibility that the pathogen may have mutated, to now be transmitted from mammal to mammal. “It’s one more step [towards being a] risk for human beings,” Plaza warns. However, he clarifies that the danger of this flu spreading between people is “low” — for now.

In January, the Pan American Health Organization (PAHO) published an alert about the “unusual” detection of avian influenza outbreaks in the Americas, along with confirmation, for the first time, of a case of human infection in the region. The analysis of that first case — which occurred in Ecuador — revealed the worrying lack of controls and surveillance. By the first week of July 2023, 16 countries registered cases in animals, while two had confirmed human infections (Ecuador and Chile), according to data from PAHO. Since 2003, the virus has jumped to humans nearly 900 times, killing more than half of those who have been infected.

To mitigate the spread, the Argentine authorities have recommended not handling dead animals or animals with suspicious symptoms, while avoiding direct contact (or pet contact) with these animals. Additionally, they have asked for citizens to notify them if they suspect that an animal may be infected with the virus. Dead animals that have been infected, or were suspected to have died from the virus, are buried by the authorities, so as to prevent any contamination or contagion from afflicting humans or other animals.

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