17 March 2016


The latest of many viruses to hit the headlines is called Zika, named after a forest in Uganda where it was first discovered over 60 years ago.  It is an arbovirus, related to dengue and yellow fever, and transmitted by the same Aedes mosquito.  Until recently Zika was understood to cause a mild febrile illness with uneventful recovery and no serious consequences.  This past two years a major epidemic of Zika has spread from its base in Africa to encircle tropical regions around the world, but what has made the news this past month is the report from Brazil of a frequent occurrence of severe microcephaly in infants born of women who had contracted the virus.  Unlike other arboviruses, there is pathologic evidence that Zika crosses the placental barrier and does invade the fetal central nervous system.  Since this information has just recently become available, it is too early to understand the exact relationship of the virus to fetal microcephaly, and the degree of fetal risk to a pregnant woman who contracts Zika.  It is known that the microcephaly causes severe disability and usually early death.  As a consequence, the World Health Organization and the Center for Disease Control have issued an advisory for women who are pregnant or of child-bearing age to avoid travel to countries that are involved in the current epidemic.  This includes Central America, Southern Mexico, the Caribbean, including Cuba, Sub-Saharan Africa, Tropical Pacific Islands and Southeast Asia.  It is important to know that there is no treatment for Zika and no vaccine is on the horizon.  Prevention of mosquito bites is of some help, but given the widespread presence of the Aedes mosquito in both urban and rural areas, total prevention of bites would be very difficult.  Be mindful also that there is evidence that Zika can be sexually transmitted.  If you are planning a trip to any of the affected areas, be sure to contact the Center for Disease Control for the latest information and advice about Zika.

Ref:   Makar, J. et al.  Zika Virus Associated with Microcephaly.  NEJM; Feb 10, 2016

Submitted by Roger Boe MD

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