Is H7N9 the next global (bird) flu pandemic?


Health workers swab a chicken to test for H7N9. Courtesy Nature/ChinaFotoPress via Getty Images.

Health workers swab a chicken to test for H7N9. Courtesy Nature/ChinaFotoPress via Getty Images.

Since 2013, the world, well really just mainly China and surrounding areas, has seen seasonal waves of an avian influenza virus, H7N9, that is a novel human pathogen. Normally this virus only infects poultry, with the occasional human cases occurring in folks who have extensive exposure to infected birds. But during this fifth epidemic wave, cases have increased dramatically and  are spreading geographically, to the point where major public health organizations around the world are getting concerned. Although the risk to the general public is low right now, this avian influenza virus is characterized as having moderate to high pandemic potential.

And that “moderate to high pandemic potential” is not good, especially when around 30% of infected persons die.

Graph showing the number of cases and deaths due to H7N9 from 2013 to 2017. This shows an increase in overall cases each year with a large spike in cases seen in late 2016 and early 2017. Courtesy WHO.

H7N9 case count, including deaths. Courtesy WHO.

But at the moment, H7N9 is not well-adapted to living in humans. Yes, it can infect humans who are consistently exposed to infected live birds, usually via live poultry markets, but once in humans we don’t really see sustained human-to-human transmission of this virus. So that’s a good thing. The bad thing is that like all influenza viruses, H7N9 can swap genes with other influenza viruses to become better (or worse) at infecting humans. All we need is a person (or pig even) to get infected with H7N9 and another influenza virus that transmits easily among humans and we could end up with a real-life repeat of the movie Contagion.

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To prevent H7N9, authorities recommend avoiding live poultry markets and touching live birds, washing your hands after you touch poultry, and cook poultry and eggs thoroughly. There’s no current vaccine for H7N9 but various public health organizations are working on developing one. Which is good news, as there are some reports of new strains that are resistant to Tamiflu, which is the recommended treatment for people with H7N9.

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