In May of 2015 the Pan American Health Organization issued an alert of confirmed Zika virus infections in Brazil. Zika virus was discovered in 1947 in Uganda in the Ziika forest. Transmission of this mosquito borne virus infection has now been reported in much of South and Central America and the Carribean. As it is currently their summer our time may come later this year as imported cases may result in local transmissions.
This RNA virus of the Flaviviridae family is primarily spread by the bite of the Aedes species of mosquito. This insect breeds in standing water and is an aggressive daytime biter. The reservoir is thought to be in humans and other primates with primate to mosquito to primate being the pathway of transmission. Rare cases of human sexual transmission have been reported.
The infection is generally mild with only 1 in 5 having the viral infection symptoms of fever, rash, arthralgia, conjunctivitis, headache or myalgias. Case hospitalization and fatality is low. Cases of Guillain-Barre have been linked to acute infection. There is no specific treatment or vaccination at this time.
The most concerning consequence, reported by the Brazil Ministry of Health, is the possible link between the Zika virus and a reported increase in babies born with microcephaly (causation not yet confirmed). Breastmilk transmission has not been reported. Cases of Zika infection in pregnant women should prompt investigation into the health of the fetus.
Given the non-specific symptoms of infection suspicion of Zika virus infection is based on the clinical features, places and dates of travel and activities. Diagnostic testing for Zika virus is limited to those State Health Departments actively pursuing testing and the CDC. Tests for other flavivirus infections (Dengue, Chikungunya) may be more widely available. PCR testing for the virus itself (molecular testing) should be done for symptoms < 7 days and IgM antibody testing for > 4 days of symptoms. Needless to say local health authorities should be notified about any concerning case.
The CDC has developed interim guidelines for clinicians caring for pregnant women during a Zika virus outbreak. Health care providers should ask all pregnant women about recent travel. Those with a history of travel to an area with Zika virus transmissions can offer testing 2-12 weeks after return from travel , those report symptoms of Zika virus disease during or within 2 weeks of travel or those with U/S findings of fetal microcephaly or intracranial calcifications should be tested for Zika infection in consultation with local or state public health officials. Testing is not recommended for pregnant women without a history of travel to a Zika transmission region.
As there is no vaccine nor prophylactic treatment pregnant women should consider postponing travel to areas with Zika virus transmission. If this is not possible then avoidance of mosquito bites is the best protection is the best strategy of all persons traveling to these areas.
submitted by Marshall Kubota MD, Regional Medical Director