Zika Virus Infection Fast Facts Here’s a look at Zika virus, an illness spread through mosquito bites that can cause birth defects and other neurological defects. Facts Zika virus is a flavivirus, part of the same family as yellow fever, West Nile, chikungunya and dengue fever. Zika is primarily transmitted through the bite of an infected female Aedes aegypti mosquito. It becomes infected from biting an infected human and then transmits the virus to another person. The Aedes aegypti mosquito is an aggressive species, active day and night and usually bites when it is light out. The virus can be transmitted from a pregnant woman to her fetus, through sexual contact, blood transfusion or by needle.