What's Up With Bird Flu?

Two summers ago as I was walking along one of my favorite Lake Michigan beaches hunting Petoskey stones I saw a dead merganser lying at the water’s edge. That’s not too unusual—I sometimes find dead birds on the beach (although not usually a merganser). But as I walked on I found more. And more. Each day I found more dead waterfowl on the beach. So I wrote the Department of Natural Resources and their response, summarized, was “it’s probably bird flu, don’t touch them, but if you do, bring it to us for necropsy.”

Well, I didn’t touch any of the birds. Bird flu—formally, influenza A (H5N1), avian influenza, or simply “H5N1”—is a nasty virus. Outside the US, the human mortality rate is about 50%. In the US there have been one or two deaths out of the 70 or so reported cases. And while that is pretty horrifying, H5N1 thankfully doesn’t spread between human beings—people catch it from animals. You’ve probably had the “pleasure” of paying high prices for eggs at the supermarket, or paying an egg surcharge at a restaurant. So far, millions of chickens have been destroyed due to bird flu.

But H5N1 doesn’t just infect chickens (and mergansers)—it’s been found in domestic cats—who have a well-known taste for birds—and dairy cattle. When it infects dairy cattle it usually isn’t fatal, but it can, among other things, change the milk collected. More on this below.

Clearly bird flu can have a devastating economic effect on poultry and dairy farming. But what about a more direct threat to people?

There are a couple of ways bird flu can become more of a direct threat. As we’ve seen, interacting with infected animals can sicken people—if you keep chickens in the backyard, you need to take precautions. And raw (unpasteurized) cow’s milk can also be a source of infection (in addition to the other dangers such as E.coli, Campylobacter, Salmonella, Listeria, and many other nasty pathogens). Unfortunately Robert Kennedy, Jr., the current head of Health and Human Services, wants to make raw milk easier to access, which would be a public health disaster.

But catching bird flu from animals is unlikely by itself to be a huge public health problem, at least in comparison to bird flu becoming a human pandemic. There are a couple of ways this can happen—flu viruses mutate constantly and an unlucky mutation could make bird flu transmissible between humans. Also, if a human catches bird flu while infected with a “regular” flu virus, the viruses can trade genetic information, leading to a very nasty, contagious bird flu that could easily become a pandemic. To prevent this, it’s essential to stop the spread of bird flu, and to keep it away from humans. This is why it’s essential to track the virus and contain it, even if this means destroying millions of chickens. Unfortunately, Kennedy (again) has a dangerous and erroneous idea that we should just let the virus spread, find the chickens that seem naturally resistant, and use them to raise new flocks (or something like that).

This is not how we control infectious diseases. There are many obvious reasons that this strategy is horrible. One is that the more we allow bird flu to spread, the more likely it is to become a human problem. Another is that it will lead to the needless culling of millions of more birds, cattle, etc. And it also doesn’t work. There’s no reason to think we can “breed out” bird flu—it is constantly mutating and it will find a way to survive.

So, when it comes to bird flu, no, it’s not time to panic, but it is time to be very aware and very cautious. We need to carefully monitor our livestock and other animals, such as outdoor cats. We need to stay vigilant, and we need to practice science-based epidemiology and infection control. If we rely on ignorance, wishful thinking, or simply incorrect views on biology from leaders, we will certainly see a new pandemic eventually.

Stay well.

-pal