U.S. health officials have issued new guidance for women who might have been exposed to the Zika virus, a mosquito-borne infection that can cause brain damage in a developing fetus.
The Centers for Disease Control and Prevention on Thursday warned that the virus is spread through mosquito bites, and there are no vaccines to prevent the spread nor drugs to treat those infected.
The agency issued a warning to pregnant women to avoid travel to 14 countries and territories in the Caribbean and Latin America affected by the virus. Those countries are Puerto Rico, Martinique, Haiti, El Salvador, Guatemala, Honduras, Panama, Brazil, Colombia, French Guyana, Paraguay, Suriname, Venezuela and Mexico.
It said that while there is no evidence to suggest that pregnant women are more susceptible to Zika virus infection, they can be infected in any trimester.
"We are quite concerned about the potential complications to the fetus of a Zika virus infection of pregnant women, and so we really are advising that pregnant women seriously consider postponing travel to these areas if possible," said Dr. Beth Bell of the CDC.
Exposure, repellents, screens
Pregnant women traveling to impacted areas should take precautions to limit their exposure to mosquitoes, the agency said.
"Mosquitoes bite not just at night, but also during the day,” Bell said. “And so the measures that people need to take to prevent mosquito bites, they have to use all the time, not just at night."
Travelers also are advised to stay in places with screens on their doors and windows, wear protective clothing and use insect repellents such as DEET.
The virus has been linked to a rising number of cases of microcephaly, a condition associated with small head size and brain damage. Brazil and Colombia lead the countries with the most reported infections, but it is spreading rapidly in neighboring countries.
Last week, U.S. health authorities confirmed the birth of a baby with microcephaly in Hawaii to a mother who had been infected with the Zika virus while visiting Brazil last year.
The CDC urged doctors to ask pregnant women about their travel history. Women who have traveled to regions in which Zika is active and who report symptoms during or within two weeks of travel should be offered a test for Zika virus infection.
The symptoms for Zika include mild fever and rash. An estimated 80 percent of people infected with the virus have no symptoms at all, making it difficult for pregnant women to know whether they have been infected.
Bell stressed that there are still many unknowns about the Zika virus.
"This is an emerging situation, it's an emerging virus and things are definitely going to change," she said.
Scientists first discovered the virus in Uganda in 1947 while studying monkeys, and isolated it in the 1950s in a human in Nigeria. But medical historians say confirmed cases were rare until 2007, when an outbreak was identified in the South Pacific Federated States of Micronesia.
Ahead of the current Latin America crisis, cases have been identified in Polynesia, Easter Island, the Cook Islands and New Caledonia.