Zika virus, originally identified in 1947 from Zika forest of Uganda, is transmitted to people primarily through the bite of an infected Aedes species mosquito. These mosquitoes are found throughout tropical regions of the world and are the same mosquitoes that spread dengue and Chikungunya viruses. Mosquitoes become infected with the Zika virus when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites. There is no vaccine to prevent or medicine to treat Zika virus infection.
Outbreaks of Zika have occurred in Africa, Southeast Asia, and the Pacific Islands. Because the Aedes species mosquitoes that spread Zika virus are found throughout the world, it is likely that outbreaks will spread to new countries. To date, Zika virus has been reported in several countries and territories in the Americas. Brazil is investigating the possible association between Zika virus infection and cases of microcephaly (smaller than expected head size) in infants.
The most common symptoms of Zika virus disease are fever, rash, joint pain, and conjunctivitis. The illness is usually mild with symptoms lasting from several days to a week. Infection is thought to provide lifelong immunity. Severe disease requiring hospitalization is uncommon. Deaths are rare. Travelers returning from areas with Zika activity should seek medical care if they experience a fever and symptoms of infection. Health care providers in areas with reported cases should be on the alert for possible cases.