According to the World Health Organization, Zika virus disease is transmitted primarily by Aedes mosquitoes. It may also be transmitted sexually, and other modes of transmission (such as through blood transfusions) are under study. While the disease commonly has only mild effects in adults, there is scientific consensus that the virus can cause microcephaly in newborns, which can result in serious, long-term impairments. The mechanism of how Zika infection during pregnancy causes disruptions in brain growth and development as well as links to other neurological complications are also being investigated.