Dated 12/31/15

The U.S. Embassy in Brasilia, Brazil informs U.S. citizens of a public health concern regarding the mosquito-transmitted Zika virus.


As dengue and chikungunya, the main transmitter of the Zika virus is the Aedes egypti, an urban mosquito that prefers to breed in and around homes.  Large urban centers with surrounding poorer slums are ideal breeding grounds for Aedes egypti.  Once infected mosquitoes become established in an area they are hard to contain.

The Zika virus is closely related to dengue.  In 2007 the first known outbreak in humans occurred on the island of Yap in Micronesia and was followed by outbreaks in other Pacific Islands.  Brazil reported its first case of Zika virus disease in May 2015.

Zika has often been called “dengue light.”  Like dengue, only about 25 percent of those infected with Zika develop symptoms.  These may include fever, headache, arthralgia (joint complaints), conjunctivitis (eye inflammation), and a maculopapular (red raised) rash that is generally not as severe as that caused by dengue or chikungunya.  There are no hemorrhagic manifestations and no long term complications. People rarely become ill enough to require hospitalization. On rare occasions, there have been deaths associated with Zika infection.

Authorities are investigating a possible association between the Zika virus outbreak and increased numbers of babies born with microcephaly, a condition characterized by small head size and associated with cognitive impairment.  As of the end of December, nine states in northeastern Brazil have reported 2,608 cases of microcephaly, a marked increase from previous years. As of the end of December, the state of Pernambuco has reported 150 affected babies – for 2015, compared with only 10 microcephalic babies reported in all of 2014.  The Zika virus was found in the amniotic fluid of two affected babies.  There is no indication that any pregnant woman needs to leave an area that has Zika infections at this time.

There is no vaccine or treatment for Zika, so prevention of mosquito bites is the only way to avoid infection.  Pregnant women in particular should employ good personal protective measures to minimize the risk of Zika and other mosquito borne infections.  These include use of CDC recommended topical repellants such as DEET or Picaridin, keeping arms and legs covered when outdoors and use of permethrin treated fabrics for clothing and tents.