CDC Warns Travelers, Especially Pregnant Women, About Zika Virus

This article was originally published in Lab Tests Online.

The U.S. Centers for Disease Control and Prevention (CDC) has issued a travel alert for more than 20 countries, primarily in South and Central America and the Caribbean, because of an outbreak of Zika virus, an infectious disease spread by mosquitos.

The situation is changing rapidly as more cases are found. The CDC continues to monitor Zika throughout the world and will add countries to the travel advisory as needed. Travelers can check the CDC page on Zika-affected Areas before their trip, especially if they are or could become pregnant.

In about 80% of cases, the Zika virus causes no symptoms and in the rest, it causes only mild illness with symptoms lasting from a few days to a week. The most common symptoms include fever, rash, joint pain, and conjunctivitis (pink eye).

However, within the last year, over 3,000 women in Brazil have given birth to babies with a condition called microcephaly (very small heads) and have tested positive for the virus. The number of these cases has increased more than 20-fold over the previous year. Investigations are ongoing to explore the link between Zika infection during pregnancy and babies born with microcephaly.

In the U.S., cases of Zika were recently confirmed in residents of several states. However, everyone diagnosed with the virus had traveled to countries where Zika has been detected. To date, no cases have been diagnosed that originated in the United States.

The CDC is recommending that women who are pregnant postpone travel to countries included in the travel notice and that women who are considering becoming pregnant speak with their healthcare practitioners before making plans to travel.

Healthcare providers caring for pregnant women should ask them about recent travel, advises the CDC. Pregnant women who have symptoms consistent with Zika virus infection and recently traveled to countries where the outbreak is occurring should be tested. A diagnosis can be made during the first week of an infection by testing a blood sample and detecting the genetic material (RNA) of the virus. A blood test to detect antibodies to the virus can also be done. Only a few state public health laboratories and the CDC are equipped to perform the test and results can take from four days to two weeks.

There is no Zika vaccine currently available and no medicine to treat the virus, so prevention to avoid mosquito bites is key, especially for pregnant women who must travel to one of the areas of concern, says the CDC. The mosquito transmitting Zika virus, the Aedes mosquito, generally bites during the day, though precautions should be taken at all times, including:

  • Wearing long-sleeved shirts and long pants
  • Using EPA-registered insect repellents containing DEET, picaridin, oil of lemon eucalyptus (OLE), or IR3535m and only used as directed, including precautions for pregnant women and children
  • Treating boots, socks, pants and tents with permethrin, a repellant
  • Sleeping in rooms that are screened in or air conditioned


Centers for Disease Control and Prevention. Press release: CDC Issues Interim Travel Guidance Related to Zika Virus for 14 Countries and Territories in Central and South America and the Caribbean. January 15, 2016. Available online at Accessed January 21, 2016.

Centers for Disease Control and Prevention. Facts About Microcephaly. Available online at Accessed January 21, 2016.

Centers for Disease Control and Prevention. Zika Virus. Available online at Accessed January 21, 2016.

Centers for Disease Control and Prevention. Diagnostic Testing. Available online at Accessed January 21, 2016.

Sun, Lena H. CDC: 'Dozen or so' cases of Zika virus among U.S. residents. The Washington Post. January 20, 2016. Available online at Accessed January 21, 2016.

(January 22, 2016) CDC Morbidity and Mortality Weekly Report (MMWR) 65(2);30–33. Available online at Accessed January 25, 2016.