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Some 700,000 birds have been culled

Avian flu killing birds in Israel could jump to humans, warns epidemiologist

Prof. Amnon Lahad calls prospect of virus crossing species ‘very concerning,’ as Health Ministry advises Israelis to avoid sick birds and not to buy unregulated chicken, eggs

Nathan Jeffay is The Times of Israel's health and science correspondent

Gathering the carcasses of wild cranes killed by avian flu at the Hula Lake Nature Reserve in northern Israel, December 27. (Hadas Kahaner, Israel Nature and Parks Authority)
Gathering the carcasses of wild cranes killed by avian flu at the Hula Lake Nature Reserve in northern Israel, December 27. (Hadas Kahaner, Israel Nature and Parks Authority)

The danger of Israel’s bird flu outbreak jumping to humans is real and “very concerning,” according to a top epidemiologist.

Prof. Amnon Lahad, chairman of Israel’s National Council for Community Health, told The Times of Israel that he is tracking the avian outbreak, which has killed thousands of wild birds.

“The widespread nature of the avian flu is very concerning, especially given that it is infecting chickens and not just wild birds. It’s made the move from wildlife to stock animals, and I’m hoping it won’t make the next step to humans,” he said Wednesday.

Most bird flu strains don’t infect humans. However, four strains have caused concern: H5N1 since 1997, H7N9 since 2013, H5N6 since 2014 and H5N8 since 2016. Lahad said that since little is known about the current infections, the possibility of a jump to humans must be taken seriously.

He said that a jump to humans could occur after a mutation, but that it’s also entirely possible the flu could cross species without a mutation.

In terms of transmission method, humans are “highly unlikely” to catch bird flu from eating infected chicken or eggs that come from an infected bird, said Lahad. This is because influenza, like the coronavirus, normally enters the body through the respiratory tract, not the gut.

Prof. Amnon Lahad (Hebrew University)

However, Lahad warned, “it could be transmitted through contact with sick birds — not from touching or eating them, but rather through the same method we know from COVID, namely droplets passing into the respiratory system,” he said.

He noted that while the entrance to the body for flu is through the respiratory system, the secretion may be from other systems. This means that if people do get infected, it could happen when they breathe in particles dislodged from freshly passed droppings, for example, if a person is clearing droppings and breathes in such particles, Lahad said.

Also Wednesday, the Health Ministry warned Israelis to take precautions amid the avian flu outbreak, urging the public to avoid coming in contact with sick or injured birds, and to not hunt such animals.

In addition, people should only purchase chicken and eggs from regulated places that have inspection stamps. According to the ministry, “care should be taken to thoroughly cook eggs and chicken, maintain hygiene and wash hands after contact with the meat or eggs.”

Preventing possible transmission to humans is one of the guiding principles of the Agriculture Ministry’s decision to cull huge numbers of birds — some 700,000 have been killed over the past few weeks.

Culling has been shown effective in the past. For example, after the first known transmission to humans in Hong Kong in 1997, with 18 cases causing six deaths, no more cases were recorded after culling.

However, bird experts stressed that culling by no means ensures the end of infection.

“This culling is the most that people can do, but nothing gives guarantees,” Tel Aviv University ornithologist Prof. Yossi Leshem told The Times of Israel. “The flu can carry on spreading among birds, and could spread to humans.”

Israel is on a major migration route and birds could disseminate the flu far beyond the country, experts believe. The disease has reached Israeli farms.

Illustrative image: A photograph from Israel’s 2006 avian flu outbreak, with Agriculture Ministry workers burying the carcasses of dead turkeys at Kibbutz En Hashlosha in the western Negev. (chameleonseye via iStock by Getty Images)

Lahad, chairman of Hebrew University’s family medicine department and head of the Jerusalem district for Clalit Health Services, said Israelis should avoid contact with birds, and spurn visits to farms with chickens and other birds. If they have cats that bring dead birds home, he urged, they should take care to dispose of them using gloves and handling them at arm’s length.

While Lahad said it was impossible to predict the likelihood of bird flu passing to humans, or the likely virulence of the disease if it does, he noted that in the past it is has caused serious illness. As this year’s flu vaccines did not include specific protection against avian flu, they are likely to provide only minimal coverage.

Asked about the likely infectiousness among humans if the flu jumps species, he said, “Influenza doesn’t spread like Omicron, but can spread at the speed of Delta, yet in the past bird flu specifically doesn’t spread so fast. Nevertheless, we don’t want to see this reaching humans. We have Omicron — we really don’t need another infectious disease.”

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