dengue fever

Protected by a mosquito net, Nadia Gonzalez recovers from a bout of dengue fever at a hospital in Luque, Paraguay Friday, Feb. 5, 2016. Dengue, like the Zika virus, is transmitted by the same vector, the Aedes aegypti mosquito. Zika was discovered in a Ugandan forest in 1947 and until last year, the virus had never caused serious disease. It has now spread to more than 20 countries. (AP Photo/Jorge Saenz)

Jorge Saenz/AP

Protected by a mosquito net, Nadia Gonzalez recovers from a bout of dengue fever at a hospital in Luque, Paraguay. Dengue, like the Zika virus, is transmitted by the same vector, the Aedes aegypti mosquito

Pakistani patients, suffering from the mosquito-borne disease, dengue fever, lay in beds covered with nets at an isolation ward of a hospital in Rawalpindi, Pakistan, Thursday, Oct. 24, 2013. Dengue, a flu-like illness, is spread by the Aedes mosquito and spikes during the annual monsoons in Pakistan, when the rains leave puddles of stagnant water where the insects breed.

Muhammed Muheisen/AP

Patients suffering from the mosquito-borne dengue fever in an isolation ward at a hospital in Rawalpindi, Pakistan. The disease is particularly prevalent during the monsoon season

An Indian man covers his nose as a Delhi municipal worker fumigates the area to prevent mosquitos from breeding after the number of dengue fever deaths in the city rose, in New Delhi, India, Thursday, Sept. 26, 2013. Dengue fever is a potentially serious mosquito-borne virus.

Manish Swarup/AP

An Indian man covers his nose as a municipal worker fumigates the area to prevent mosquitoes from breeding after the number of dengue fever deaths rose in New Delhi. Dengue fever is a potentially serious mosquito-borne virus.