The first case of Zika in the United States was reported in late December in Puerto Rico, and more cases of this and other tropical diseases once unheard of in the U.S. are likely to surface in the future, according to the Wall Street Journal.
Here are five things to know about Zika, other emerging tropical diseases and what's causing this change.
1. Zika virus is transmitted to people via a specific species of mosquito found through tropical regions of the world that also transmits chikungunya and dengue viruses, according to the CDC. Mosquitoes get the virus by biting infected humans, and then spread the virus when biting other people.
2. There is no vaccine or treatment available for Zika, but the CDC calls the illness "usually mild," noting that "severe disease requiring hospitalization is uncommon," and that "deaths are rare." However, earlier in December, the World Health Organization named Zika as a "serious" emerging disease that requires swift action to contain. Additionally, the CDC urged healthcare providers in affected areas to be on alert for possible cases.
3. Zika is not the only tropical disease to show up recently in the U.S.: Chikungunya appeared in Florida, Puerto Rico and the U.S. Virgin Islands for the first time in 2014. Similarly to Zika, no treatment or medicine exists for this mosquito-borne illness, and the WHO labeled it as a "serious" emerging disease.
4. Factors such as climate change and international travel contribute to the spread of these tropical diseases, according to the Wall Street Journal. "The weather is hotter; cheap airfares mean humans travel more than they did decades ago; and cities in tropical countries are becoming more crowded, creating nurseries for each disease," according to the report.
5. Pest control is "crucial" in stopping the viruses' spread, according to the Wall Street Journal. People traveling to Puerto Rico and other tropical areas should wear bug repellant, use screens to keep mosquitoes outside, empty standing water areas and cover up skin with clothing to prevent infection, according to the CDC.