Zika virus is a mosquito-borne flavivirus that was first identified in Uganda in 1947 in monkeys. It was later identified in humans in 1952 in Uganda and the United Republic of Tanzania. From the 1960s to 1980s, rare sporadic cases of human infections were found across Africa and Asia, typically accompanied by mild illness. In year 2015, Brazil reported a large outbreak of rash illness, soon identified as Zika virus infection. The infection was found to be associated with Guillain-Barré syndrome and microcephaly (smaller than normal head size) in newborns. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific. To date, a total of 86 countries and territories have reported evidence of mosquito-transmitted Zika infection.
Zika virus is primarily transmitted by the bite of an infected mosquito, mainly Aedes aegypti, in tropical and subtropical regions. This is the same mosquito that transmits dengue, chikungunya and yellow fever. Ae. aegypti is a day-time feeder, and its peak biting periods are early in the morning and in the evening before dusk. Female Ae. aegypti bites multiple people during each feeding period. Additionally, Zika virus can also be transmitted from mother to fetus during pregnancy, through sexual contact, transfusion of blood and blood products, and organ transplantation.
The incubation period of Zika virus disease is estimated to be 3–14 days. The majority of people infected with Zika virus do not develop symptoms. Symptoms are generally mild including fever, rash, conjunctivitis, muscle and joint pain, malaise, and headache, and usually last for 2–7 days. Zika virus infection during pregnancy is a cause of microcephaly and other pregnancy complications such as fetal loss, stillbirth, and preterm birth. Zika virus infection is also a trigger of Guillain-Barré syndrome, neuropathy and myelitis, particularly in adults and older children.Infection with Zika virus may be suspected based on symptoms of persons living in or visiting areas with Zika virus transmission. A diagnosis of Zika virus infection can only be confirmed viral isolation during the first few days of infection using reverse transcriptase-polymerase chain reaction (RT-PCR) from the blood, urine or semen. There is no treatment available for Zika virus infection or its associated diseases. Treatment is directed primarily at relieving the symptoms, including using anti-pyretics, optimal analgesics and fluids.
Protection against mosquito bites during the day and early evening is a key measure to prevent Zika virus infection. Special attention should be given to prevention of mosquito bites among pregnant women, women of reproductive age, and young children. Personal protection measures include wearing clothing that covers as much of the body as possible; using physical barriers such as window screens and closed doors and windows; and applying insect repellent to skin or clothing. No vaccine is yet available for the prevention or treatment of Zika virus infection. For regions with active transmission of Zika virus, all people with Zika virus infection and their sexual partners (particularly pregnant women) should receive information about the risks of vertical and sexual transmission of Zika virus.
Centers for Disease Control and Prevention. About Zika: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD) [updated 20 May 2019]. Available from: https://www.cdc.gov/zika/about/index.html.
Krauer F, Riesen M, Reveiz L, Oladapo OT, Martínez-Vega R, Porgo TV, et al. Zika Virus Infection as a Cause of Congenital Brain Abnormalities and Guillain–Barré Syndrome: Systematic Review. PLOS Medicine. 2017;14(1):e1002203.
Weaver SC, Costa F, Garcia-Blanco MA, Ko AI, Ribeiro GS, Saade G, et al. Zika virus: History, emergence, biology, and prospects for control. Antivir Res. 2016;130:69-80.
World Health Organization. Zika virus [updated 20 July 2018]. Available from: https://www.who.int/news-room/fact-sheets/detail/zika-virus.