Zika virus is an enveloped, positive-sense single-stranded RNA virus belonging to the genus *Flavivirus*. It was first isolated in 1947 from a sentinel rhesus monkey in the Zika Forest of Uganda. Zika virus is primarily transmitted by *Aedes* mosquitoes, especially *Aedes aegypti* and *Aedes albopictus*, and can also spread via sexual contact, vertical transmission from mother to fetus, and blood transfusion.
Virology and transmission
Zika virions are roughly 40 nm in diameter with an icosahedral capsid surrounded by a lipid envelope studded with envelope (E) and membrane (M) proteins. The viral genome encodes a single polyprotein that is cleaved into structural and non-structural proteins. After entry into a host cell via receptor-mediated endocytosis, the virus replicates in the cytoplasm and assembles progeny virions that bud into the endoplasmic reticulum. Mosquitoes acquire the virus by feeding on viremic hosts; following an extrinsic incubation period, the virus replicates in the mosquito’s midgut and salivary glands, enabling subsequent transmission. Non-vector routes include sexual transmission from infected semen, intrauterine transmission causing fetal infection, and transfusion of contaminated blood products.
Clinical manifestations and public health impact
Human infection with Zika virus is often asymptomatic or produces a self-limited illness characterized by fever, maculopapular rash, conjunctivitis, arthralgia, and headache. However, the 2015‑2016 outbreak in the Americas revealed a link between maternal Zika virus infection and congenital malformations, most notably microcephaly and other neurodevelopmental anomalies collectively termed congenital Zika syndrome. Zika virus infection has also been associated with Guillain–Barré syndrome in adults. There is currently no specific antiviral therapy or licensed vaccine, so prevention focuses on controlling mosquito populations, using repellents and bed nets, practicing safe sex, and screening blood donations. Surveillance and rapid diagnostic testing are essential for outbreak response and protecting pregnant individuals.
Although Zika virus typically causes mild disease, its capacity to cross the placenta and disrupt fetal development underscores the need for continued research, surveillance, and vector control. Understanding its transmission dynamics and pathogenesis informs public health strategies to mitigate future outbreaks.
Related Terms: Flavivirus, Aedes mosquito, Microcephaly, Congenital Zika syndrome, Arbovirus