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Skunks, sea lions, foxes: they are the most recent victims of bird flu, in a global outbreak that has now lasted a year and a half. Although it became clear on Friday that effective vaccines exist against the current pathogenic H5N1 variant, that does not mean that the outbreak will soon be over. Experts are concerned about the increasing number of infections among wild birds, including in South America.
Op The bird flu virus was first detected on that continent at the end of last year, in large groups of pelicans on the west coast of Peru. A turning point, thinks virologist Thijs Kuiken of Erasmus MC, who has been researching bird flu for more than twenty years. “This virus variant, which was first observed in 1996, had never been to South America before. So now there is a major outbreak, which is spread via wild birds.”
Thousands of dead sea lions
Because after Peru, other countries were also affected by H5N1 in a short time. The virus variant is now found in Chile, Uruguay and Argentina, among others, and not only in birds. For example, the authorities of Peru announced at the beginning of this month that more than 3,400 sea lions have so far died of bird flu in that country, just over 3 percent of the total sea lion population there.
The H5N1 outbreak has reached about 42 degrees south latitude, near the southern tip of South America:
In a recent bird flu report, the European food safety authority EFSA warns against the transfer of the H5N1 virus variant to Antarctica. There is a considerable chance that this will happen, according to the article published a week and a half ago rapport. This is due to the rapid spread of the virus in South America and because there are many known flight paths of wild birds between South America and Antarctica.
“That would have enormous consequences,” says virologist Kuiken. “It is estimated that there are about 100 million breeding birds in Antarctica, such as penguins, albatrosses and all kinds of other seabird species. Not to mention all the marine mammals in the area. If the virus ends up in seabirds, you can assume that it will also ends up in the marine mammals.”
crab eaters
EFSA also expects the virus to jump to mammals once it has reached Antarctica. The European watchdog cites as an example the 15 million crabeaters on the southern continent, a seal species that only occurs around Antarctica (and which does not eat crabs, but mainly krill).
“They are all susceptible to this virus,” says Kuiken. “So this could make the disaster in nature even bigger.” In comparison, an estimated 150,000 common (grey) seals live in the North Sea.
Incidentally, it is not certain that the H5N1 variant of bird flu can also jump between mammals. Researchers do suspect that mammals can infect each other, for example recently in a mink farm in Spain, but hard evidence for this is still lacking. “But sometimes so many mammals are found dead at the same time that we cannot rule out that the virus has passed from mammal to mammal,” explains Kuiken.
The vaccines that started this article cannot prevent the feared deaths of wild birds. But vaccination offers major advantages for the poultry sector, emphasizes Kuiken. For example, chickens on an infected farm no longer have to be culled once they have been vaccinated. Vaccinations will also lead to a slower circulation of the virus in the poultry sector, which will reduce the chance that bird flu will spread from poultry to humans.
But the virus will not disappear for the time being, Kuiken summarizes. “It is too late for that. The virus has now adapted to wild birds and no longer needs the poultry population to survive. Science helps us to see how the virus spreads almost daily, but unfortunately not to prevent the virus to stop.”
