Zika virus is a viral disease related to dengue fever. A flavivirus, Zika is an emerging virus that has spread from its origins near equatorial Africa and Asia to the Americas. It is transmitted primarily by the bite of the Aedes aegypti mosquito and to a lesser extent Aedes albopictus. Sexual transmission has been reported, and Zika has been detected in semen for greater than 90 days following infection. In utero transmission has been reported; thus, safe sex precautions should be observed for 90 days following exposure.
Symptoms of infection are generally mild, with patients reporting a low-grade fever, a maculopapular rash that may start on the face and spread to the remainder of the body, associated arthralgia, and conjunctivitis. Headaches are common. The incubation period for Zika virus is 3 to 14 days. Previous infection with Zika usually precludes future infection due to immunity.
The virus is associated with an increased incidence of Guillain-Barré syndrome. It is known to cause severe congenital defects including microcephaly and chorioretinal scarring if contracted during pregnancy. The chance of congenital birth defects is highest with first-trimester infection and diminishes for illness contracted later in pregnancy. The incidence of congenital birth defects following congenital disease infection is estimated to be 5% to 10%. Previous infections with dengue may provide some cross-immunity to Zika infection. Although laboratory abnormalities are not common, occasional leukopenia, thrombocytopenia, and mild transaminitis are sometimes identified. Diagnosis can be confirmed with a reverse transcriptase PCR (RT-PCR) in the acutely ill patient. The virus may be detected in the urine up to 14 days after onset of symptoms. Later diagnosis can be confirmed by IgG and IgM antibodies to Zika virus.
Management and Disposition
Supportive therapies for pain, fever, and rash are the mainstays of therapy. False-positive testing with IgM is usually observed due to cross-reaction with other flaviviruses. Aspirin and nonsteroidal anti-inflammatory drugs should be avoided as there a risk of increased hemorrhagic complications in the event the illnesses caused by Dengue fever. Those who are planning on conceiving should wait at least 3 months after exposure to Zika or travel to endemic regions before engaging in unprotected sex. Admission is indicated for those with severe symptoms or an uncertain diagnosis.
Presentation of Zika virus infection. (A) Edema and erythema of the malar region of the face and conjunctival injection. (B) Macular rash on the abdomen. (C) Hyperemia and petechiae in the hard palate. (D) Tender, mobile, soft lymph node, about 15 mm in diameter, behind the left ear.(Reproduced with permission from Brasil P, Calvet GA, de Souza RV et al. Exanthema associated with Zika virus infection. Lancet Infect Dis. 2016;16(7):866. Copyright © Elsevier.)