West Nile virus first appeared in North America in 1999. And it quickly moved across the continent. Now a study has pinned the proliferation on a particular culprit: robins. The work is published in the journal Science. [A. Marm Kilpatrick, "Globalization, Land Use, and the Invasion of West Nile Virus"]

A variety of animals can serve as hosts for West Nile, but the virus primarily spreads through a few species of mosquitoes that usually feed on birds, and those bird species, which become viral hosts. Robins may not be the most abundant of birds, but mosquitoes find their blood particularly tasty, frequently feeding on them and turning them into viral “super-spreaders.”

In fact, the virus may be why the once-growing robin population has leveled off. The mosquitoes and birds responsible for West Nile’s spread abound where people also live, raising the odds that a mosquito that picked up the virus feeding on a robin could transmit it to a person.

Knowing that the spread of mosquito-borne disease depends on the insects’ feeding habits could help researchers predict and prevent the spread of new pathogens. As Dickenson said, hope is the thing with feathers. Even if it’s infected.

—Sophie Bushwick

[The above text is a transcript of this podcast.]