A 'tropical disease' carried by sand flies is confirmed in a new country: the U.S.

Sand flies carry the protozoan parasites that spread leishmaniasis. It was thought to be a disease of tropical climates, but leishmaniasis-causing parasites have now been found living and circulating in the United States. (Science Photo Library via Science Source)

Back in 2014, dermatologist Bridget McIlwee saw a 3-year-old patient in central Texas with unusual bumps on his ear.

"They looked a little bit like almost kind of a benign mole that you would see in a child, except that you wouldn't expect something like that to come up quickly and then multiply," she says.