Zika Virus

Zika is a mosquito-borne flavivirus that, for most people, causes a mild illness like a brief flu. But in a pregnant woman, the virus can cross into the fetus and cause severe, lifelong brain damage in her baby.

The disease

Zika is closely related to dengue and yellow fever, and like them it spreads mostly through the bite of Aedes mosquitoes — particularly Aedes aegypti, the same species that carries dengue. It can also pass between people through sexual contact, and from a pregnant woman to her fetus. Most infected people never know they had it; those who do typically come down with a few days of fever, rash, joint pain, and red eyes.

What changed Zika from an obscure tropical disease into a global concern was a different effect: when a pregnant woman is infected, the virus can damage her baby's developing brain. The result, called congenital Zika syndrome, includes microcephaly — a dangerously small head and underdeveloped brain — along with other birth defects. Rarely, the virus also triggers Guillain-Barré syndrome in adults, a neurological condition that can cause temporary paralysis.

The 2015 wake-up call

Zika was first isolated in 1947 from a forest in Uganda and stayed largely overlooked for nearly seventy years. Then in 2015 it exploded across the Americas. Roughly 1.5 million people were infected in Brazil alone, and over 3,500 babies were born with microcephaly linked to the virus. The World Health Organization declared Zika a Public Health Emergency of International Concern in February 2016.

The outbreak subsided, but no approved vaccine or antiviral treatment exists. Aedes aegypti continues to spread into new territory with the climate, and Zika remains endemic in much of the tropics — quietly, until the next pregnant woman is infected.

Folding@home is applying the methods developed for dengue to Zika, taking advantage of the strong similarities between the two flaviviruses.