Zika virus is a flavivirus transmitted by Aedes aegypti and Aedes albopictus mosquitoes that caused a massive outbreak across the Americas in 2015-2016. WHO declared a Public Health Emergency of International Concern when the virus was linked to a sharp rise in microcephaly and other congenital brain malformations in infants born to women infected during pregnancy.
Zika virus disease (ICD-10: A92.5) is an arboviral infection caused by the Zika virus, a single-stranded RNA flavivirus closely related to dengue, West Nile, and Japanese encephalitis viruses. The virus is primarily transmitted by the bite of an infected Aedes mosquito, with secondary transmission through sexual contact, blood transfusion, organ transplantation, and from mother to fetus during pregnancy or around the time of delivery. Most adult infections are asymptomatic (around 80%) or produce a mild self-limited febrile illness with rash. The clinical significance derives from two severe manifestations: congenital Zika syndrome — a pattern of microcephaly, brain calcifications, ocular abnormalities, and limb contractures in infants exposed in utero, especially during the first and early second trimesters — and Guillain-Barre syndrome, an immune-mediated polyneuropathy occurring days to weeks after infection.
The key symptoms of Zika Virus are: Low-grade fever (37.5-38.5°C) developing 3-14 days after a mosquito bite in an endemic area., Pruritic maculopapular rash starting on the face or trunk and spreading distally over 2-3 days., Non-purulent bilateral conjunctivitis with red eyes and mild discomfort but no discharge., Arthralgia or polyarthritis, typically of the small joints of the hands and feet, that lasts up to 1 week., Retro-orbital pain that worsens with eye movement, often a clinical clue toward an arboviral illness., Headache, often moderate, frontal or retro-orbital, lasting 3-5 days., Generalized myalgia, fatigue, and malaise lasting up to 1 week..
Suspect Zika in any person with compatible symptoms (fever, maculopapular rash, conjunctivitis, arthralgia) and possible exposure (travel to or residence in an active transmission area, sexual contact with an exposed partner, or living in a region with local Aedes vectors). Pregnant women with even a suspicious exposure history warrant testing regardless of symptoms. Diagnosis uses molecular and serologic tests with timing-dependent sensitivity. Reverse-transcription PCR (RT-PCR) on serum within 7-10 days of symptom onset and on urine within 14 days is the most specific test; RT-PCR on amniotic fluid and on cord blood/neonatal serum at birth contributes to congenital diagnosis. Serology (IgM ELISA) becomes positive 4-7 days after symptom onset but cross-reacts extensively with dengue, yellow fever, West Nile, and Japanese encephalitis antibodies; positive IgM is followed by plaque-reduction neutralization testing (PRNT) for species specificity. Concurrent dengue and chikungunya testing is mandatory because the three viruses co-circulate, present similarly, and have very different management implications. In pregnancy, serial fetal ultrasound at 3-4 week intervals from the time of suspected exposure tracks head circumference, ventricular size, and brain echogenicity. Neonates exposed in utero undergo head ultrasound or MRI, ophthalmologic examination, and auditory screening at birth and again at 1, 6, and 12 months. Adult patients presenting with neurological symptoms after a compatible illness need lumbar puncture, nerve conduction studies, and infectious disease consultation for Guillain-Barre evaluation.
Outcomes vary dramatically by clinical form. Symptomatic acute Zika in non-pregnant adults has an excellent prognosis: more than 95% recover fully within 1-2 weeks without sequelae. Post-Zika Guillain-Barre syndrome has a more variable course; most patients improve over 6-12 months with treatment but a minority have residual weakness or chronic pain. Congenital Zika syndrome carries a guarded long-term prognosis: surviving infants have lifelong neurodevelopmental disability with severe motor impairment, epilepsy, sensory deficits, and feeding difficulties. Mortality in the first year of life is around 5-10% in case series, and ongoing care needs are substantial. The 2015-2016 outbreak has been followed by lower-level endemic transmission in many countries; recurrent outbreaks are anticipated whenever vector density rises and population immunity wanes. Vaccine development is active and a licensed product would change this prognosis dramatically.
Infectious disease and maternal-fetal medicine referral is essential for any pregnant woman with confirmed or suspected Zika exposure, and for any adult with neurological symptoms after a compatible illness. Pediatric neurology, ophthalmology, audiology, and developmental pediatrics manage newborns with congenital Zika syndrome.
Find specialists →Acute symptoms in adults resolve over 2-7 days with full recovery in 1-2 weeks. Joint pain may linger for weeks in some patients. Guillain-Barre recovery is over months; most patients walk independently again by 6-12 months. Congenital Zika syndrome is lifelong; developmental gains continue with sustained therapy but full functional recovery does not occur.
Rest during the acute febrile illness. Most adults resume normal activity within 1-2 weeks. Patients with post-Zika Guillain-Barre syndrome follow structured neurological rehabilitation with progressive mobilization, strengthening, and gait training under physiotherapy. Pregnant women with Zika exposure continue routine pregnancy exercise unless complicated by other obstetric issues.
Look for an infectious disease specialist familiar with arboviral disease in your region; many academic centers run dedicated travel or tropical medicine clinics. Maternal-fetal medicine units with experience in congenital infection follow exposed pregnancies. Newborns with congenital Zika syndrome benefit from coordinated care at a tertiary children's hospital with a developmental pediatrics service.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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