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H7N9

Birth Year Predicts Bird Flu Risk

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Incidence of Avian Flu vs. Year of Birth

Caption: Birth years of people in China who contracted H7N9 avian flu from 1997-2015 (left); birth years of people in Cambodia, China, Egypt, Indonesia, Thailand, and Vietnam who contracted H5N1 avian flu from 1997-2015 (right).
Source: Adapted from Science. 2016 Nov 11;354(6313):722-726.

You probably can’t remember the first time you came down with the flu as a kid. But new evidence indicates that the human immune system never forgets its first encounters with an influenza virus, possibly even using that immunological “memory” to protect against future infections by novel strains of avian influenza, or bird flu.

In a study that looked at cases of bird flu in six countries in Asia and the Middle East between 1997 and 2015, an NIH-supported research team found that people born before 1968 were at lower risk of becoming seriously ill or dying from the H5N1 strain of the bird flu virus than were those born afterwards [1]. Just the opposite was true of another emerging strain of bird flu. People born before 1968 were at greater risk of becoming seriously ill or dying of H7N9, while those born after that date were more often protected.


Ferreting Out Flu

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Photo of two caged ferrets, one appears normal in color and playful, the other albino and skittish.

Caption: Testing transmission of the new H7N9 flu virus
Credit: Sander Herfst, Department of Virology, Erasmus Medical Center, Rotterdam, NL

The latest flu virus causing concern, H7N9, arose in birds in Eastern China a few months ago—so far infecting more than 100 people, with a high death rate [1]. To gauge the pandemic potential of this new avian virus, a team of Chinese and NIH-funded American researchers isolated the virus from a patient in China and used it to infect ferrets [2].

Yes, you read that right: ferrets! It turns out that ferret airways have biological similarity to humans, and so they are traditionally used as an indicator of whether humans are susceptible to a particular flu virus and whether transmission can occurs through the air (breathing, coughing, or sneezing) or requires direct contact.