In 2015, a tropical disease known as “Zika virus” was discovered in Brazil and confirmed by the Pan-American Health Organization. Since then, the virus has spread to many countries, mostly in Latin America and some Pacific Islands. Until recently, only a small number of people had heard of this virus. In the United States, there  haven’t been any cases of Zika transmission as of writing, but there have been reports of travel-associated cases as recently as early February.

The Zika virus is transmitted from person-to-person by mosquitoe bites and sometimes by sexual contact. The species of mosquitoes is called Aedes, the same mosquitoes that spreads other viruses such as Dengue and Chikungunya. It is believed by many medical specialists to have caused birth defects and deaths in babies born from mothers that are infected.

Symptoms associated with this disease are mild: a rash, headaches, pain in the joints and bones, and fever. The symptoms are apparent between three and 12 days after a bite, and then they go away after a week. Hospitalization and death are uncommon.

Although it might not be of serious danger in adults, Zika is a source of worry among many researchers with regard to babies born with a condition known as microcephaly. Microcephaly is a birth defect that can cause infants to be born with abnormally small heads and underdeveloped brains. According to Brazil’s Ministry of Health, the country saw 20 times more microcephaly cases in 2015 than normal.

The Center for Disease Control in the United States has issued a travel guidance to pregnant American women, with a list of countries to avoid visiting. Right now the list includes: Barbados, Bolivia, Brazil, Colombia, Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, Venezuela, and officials warn that more countries will be added soon. There is no vaccine or medicine for this virus, which is why travelers are advised to protect themselves by using mosquito repellant and wearing long-sleeve shirts and long-legged pants.