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    Zika virus and microcephaly

    Info to help you counsel your (understandably) concerned pregnant patients

    Dr Lockwood, Editor-in-Chief, is Dean of the Morsani College of Medicine and Senior Vice President of USF Health, University of South Florida, Tampa.


    Last February, an epidemic of a rash-associated mild viral illness rapidly spread through a number of northeastern Brazilian states. By May, the illness was confirmed to be due to the mosquito-borne Zika virus.1 On November 11, 2015, the Brazilian Ministry of Health declared a public emergency precipitated by reports of a 10-fold higher rate of fetal microcephaly occurring in these same Zika-affected states.

    On November 17th the Brazilian Ministry of Health reported that reverse transcription polymerase chain reaction (RT-PCR) analysis of amniotic fluid obtained from 2 women with microcephalic fetuses demonstrated the presence of Zika virus RNA. The same day the World Health Organization (WHO) issued an epidemiological alert regarding the increased occurrence of microcephaly in northeast Brazil. A few days later health authorities in French Polynesia reported at least 17 cases of fetal or infant central nervous malformations associated with an earlier outbreak of Zika virus.

    More: What you need to know about Zika virus

    In December, the Centers for Disease Control and Prevention (CDC) reported a single autochthonous Zika infection in Puerto Rico and on January 15, 2016, the CDC issued a travel advisory to pregnant women recommending they postpone travel to Mexico, Puerto Rico, and parts of Central America and South America due to the presence of the Zika virus.2 On January 22 the advisory was expanded to include parts of the Caribbean and Polynesia. In El Salvador, health officials went so far as to recommend that women postpone becoming pregnant until 2018.

    What is this new obstetrical infectious threat, how serious is it, and how should ob/gyns respond?

    Zika virus

    The Zika virus is one of 4 tropical, arthropod-transmitted viruses to threaten the United States in the past 25 years, the others being dengue, West Nile, and chikungunya. The ecological reasons for this pathogenic onslaught are debatable, but climate change, accelerated globalization of trade, and unfavorable mutations may be factors. Zika was first described in Uganda in 1947 and until recently was confined to a very narrow Afro-Asian equatorial band.1

    Over the past decade the virus has spread across Polynesia to Easter Island, and more recently into Chile, Brazil, Columbia, Suriname, and now into Central America, Mexico, and the Caribbean. This RNA flavivirus is transmitted by the Aedes aegypti mosquito with a 3- to 12-day incubation period. Three-quarters of infections are asymptomatic and when symptomatic, the disease has relatively mild manifestations, including low-grade fever, transient arthritis, a maculopapular rash starting on the face and spreading to the body, mild conjunctivitis, myalgia, headache, and asthenia.1 This presentation is similar to mild dengue and chikungunya viral infections.

    Of note, the French Polynesia and Brazilian outbreaks have also been associated with a significant increase in post-viral Guillain-Barre syndrome.1,3 A case described in 2013 in Tahiti by Musso et al supports the possibility that Zika could be sexually transmitted, but more investigation into this hypothesis is needed.4 Zika’s relatively mild, nonspecific, viral presentation coupled with the absence of commercially available serological or molecular RT-PCR testing makes rendering a definitive clinical diagnosis difficult.

    NEXT: Examining the virus-microcephaly link

    Charles J Lockwood, MD, MHCM
    Dr Lockwood, Editor-in-Chief, is Dean of the Morsani College of Medicine and Senior Vice President of USF Health, University of South ...


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