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THE NEXT PANDEMIC: H5N1 and Why You Should Be Paying Attention By Evan Anderson Why Read: This week, we cover what everyone should know about the ongoing H5N1 outbreak, why it's deadly serious, and what might be done to avoid walking straight into another pandemic. ________ The flu is very unpredictable when it begins, and in how it takes off. [. . .] The key now is to do everything in preparation and to get all of our necessary elements lined up over the summer. - Harvey Fineberg, then- president of the Institute of Medicine, discussing the 2009 outbreak of swine flu Flu pandemics are nothing new. Medical historians think the first one struck in 1510, infecting Asia, Africa, Europe, and the New World. Between the years 1700 and 1900, there were at least sixteen pandemics, some of them killing up to one million people. Yet these were tame compared to the 1918 calamity. It was by far the worst thing that has ever happened to humankind; not even the Black Death of the Middle Ages comes close in the number of lives it took. A 1994 report by the World Health Organization pulled no punches. The 1918 pandemic, it said, "killed more people in less time than any other disease before or since." It was the "most deadly disease event in the history of humanity." - Albert Marrin, Very, Very, Very Dreadful: The Influenza Pandemic of 1918 On March 11, 1918, a US infantryman fell ill with a sore throat, cough, and fever in Fort Riley, Kansas. Within a week, 522 more soldiers at the fort were also reported sick. Within the span of a few months, the entire globe had been hit with what would turn out to be the deadliest influenza pandemic yet known to man. An estimated 675,000 Americans died. Today's global estimates range from 50 million to 100 million fatalities. By now, due to the ongoing COVID-19 pandemic, we have become more accustomed to hearing tales of the 1918 flu. That pandemic serves as a strong reminder of many facts: that we have been "lucky" so far with COVID, that infectious diseases are one of the greatest threats to human life, and that "It's just the flu" isn't the reassurance that some may believe. Influenza loves a good host and a crowded environment. Thus, our most common encounters with it tend to stem from regular interactions with the animals who host it best. The 1918 pathogen (H1N1) was, as it turns out, a type of swine flu. (Many of us will recall the 2009 swine flu, which briefly went pandemic.) Pigs are an excellent breeding ground for influenza viruses, especially when living in crowded conditions, and are biologically similar enough to humans that they make for great sources for a zoonotic jump - the moment when a pathogen moves from one species to another. Birds, like pigs, also often live in crowded conditions, and regularly experience influenza outbreaks. If you were to predict the next pandemic with closed eyes and an infectious-disease background, the most obvious one would be an airborne bird or swine flu, incubated somewhere in Asia. Lucky for us, avian flu has traditionally had a harder time jumping to humans than other flus (though sporadic infections do occur). In any given year, though we don't always know it, avian flu is usually spreading in one flock or another of wild birds. (The CDC has a useful timeline of various detected subtypes and human cases throughout the years here.) This is concerning, but generally outside of our control, and it doesn't necessarily pose a great danger to human beings in and of itself. What does pose a threat is the spread of avian flu to domestic birds, with which we have a great deal of contact in the packed henhouses of modern chicken farms. This has been an ongoing battle. Most of us have heard of occasional mass culling on chicken farms in attempts to stop outbreaks of bird flu. Far more alarming, though, would be a jump from birds to something more akin to people - say, a mammalian species - with sustained transmission between individuals. This would suggest that the virus had mutated sufficiently to allow infection of a new type of host, one much closer to humans in its makeup. Enter today's flu strain.
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