Thursday, February 11, 2016

Everyone's Talking About Zika

                           Every year about this time, commercials advertising getaways to Caribbean, Central and South American destinations seem particularly enticing.  But before you pack your bags, know what you might encounter besides palm trees and tropical breezes – these days, the talk is all about arboviruses.  These are viruses spread by mosquitos and ticks and can cause potentially debilitating, sometimes fatal diseases. So it’s important to take appropriate precautions (light weight long-sleeved clothing, a good mosquito repellent, and a strong dose of common sense) when you travel to endemic locales.  

For the last few weeks we’ve been inundated with reports about Zika virus, an arbovirus that may be linked to microcephaly in infants of infected pregnant women.  Though a causal relationship has not been definitively confirmed, circumstantial evidence linking a 20-fold increase in cases of microcephaly in Brazil where concomitant Zika virus transmission is ongoing is creating panic. 

Zika is not the first, nor is it likely to be the last arbovirus that has generated alarm in the Americas.  It joins West Nile virus, dengue and chikungunya, all of which spread from Africa eastward to the western hemisphere.  Because the presenting symptoms can overlap somewhat, distinguishing between these viral syndromes can be difficult.  Zika infection does not result in hemorrhagic fever or death the way dengue can.  In fact, most often it is very mild or asymptomatic.  However, it may present with an initial flu-like illness (fever, arthralgia, conjunctivitis) and rash characteristic of the other viruses.

  So why all of the concern?  Two reasons:  an observed increase in cases of Guillain-Barre syndrome (a paralyzing neurologic syndrome) and fetal microcephaly (small brain size) in areas where Zika infection has become established.   In fact, if a causal relationship is proven, Zika would be the first flavivirus to have teratogenic effects.
There have also been recent reports of sexually transmitted Zika virus infection.  It is not yet clear how effectively it might be spread through blood and other body fluids, but the CDC and WHO have issued multiple advisories urging precaution and use of barrier protection (condoms) when engaging in sexual intercourse.

Given the potential for congenital Zika virus infection, pregnant women are strongly urged to avoid travel to endemic areas.  In addition, if a pregnant woman’s male partner has recently traveled to these areas, condoms should consistently be used during sexual intercourse.  There are no commercially available tests at this time, but if Zika infection is suspected, testing of serum samples (RT-PCR and serologies) can be performed at the CDC.  If positive, fetuses should be monitored for the development of microcephaly or brain calcification via serial ultrasound.  No vaccines or specific antiviral treatment are currently available. 

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                                                                                                                                        Judith Wolf, MD
                                                                                                                              Associate Director, WHEP




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