Is there an Issue in the Bird Flu Imbroglio?

The casual news observer will have noticed that bird flu has not gone away. In fact, as it bubbles away under the surface of the collective consciousness, the heat has been turned up recently.

In a world now hyper-sensitive to the prospect of deadly viruses, is there an issue here? 

The strain of bird flu that has caused concern since its emergence is known as H5N1. The virus has been around since the 1990s. It was the original out-of-China viral scare, circulating to an unknown degree before a Hong Kong resident was reported as infected in 1997.

The virus was initially controlled, but ended up killing hundreds of people when it spread across East Asia in 2005. It is deadly to people who catch it, but it hasn’t evolved to infect humans, and requires a lot of contact to do so.

Biocontrols around farm animals soon put an end to the 2005 epidemic, but H5N1 continued to circulate in domestic fowl populations.

What is new about the current bird-flu pandemic is that the virus has jumped to wild bird populations. At the end of February, the virus was found in wild penguins in Antarctica, after earlier reaching South America. A month ago, researchers based at Australia’s Federation University documented a mass death of over 500 Antarctic penguins, apparently caused by a virus.

Then, early in April, scientists became aware that bird flu was circulating among cattle in the United States; it is now in nine states. The strain also infected a farm worker.

Two things are going on here. One is that because the virus is endemic in wild bird populations, it won’t be able to be eradicated.

The second is due to a quirk in cow biology. H5N1 breaks into cells via something called the sialic acid receptor. Birds’ sialic acid receptors are shaped quite differently to those in human cells, but cows – well, unfortunately, cows have both kinds of receptor. 

That means that if H5N1 becomes entrenched in cows, it could quite logically mutate so as to also be able to use the human-like sialic acid receptor to break into cells. And if that ever happens, raising chickens will become a serious biohazard.

Thumbnail image courtesy of @carolienvanoijen via Unsplash.

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