EPIDEMIOLOGY

A Nasty Tropical Skin Disease Is Now Endemic in the U.S.

A unique U.S. strain of leishmaniasis has just been reported

By Simon Makin on October 19, 2023

Cutaneous leishmaniasis is one of the “neglected tropical diseases,” a disparate group of conditions that affect some of the world’s poorest people and receive relatively little global attention. Caused by parasites spread by sand fly bites, the disease is not fatal, but skin lesions, the main symptom, can bring about all sorts of issues relating to depression and stigma. “You get facial scarring for life, which causes all sorts of issues relating to depression and stigma,” says parasitologist David Molyneux of the Liverpool School of Tropical Medicine in England.

The disease is endemic in the Middle East, Asia, Africa and Latin America. Until recently, it was not widely believed to be native to the U.S. Cases have long been seen in Texas, but most were presumed to have been contracted by travelers returning from Mexico. Over the past decade or so, reports started cropping up of cases in people with no history of travel outside the U.S., suggesting that they may have caught the illness locally.

A U.S. Centers for Disease Control and Prevention team has now found nontravelers who were infected with a form of the parasite that is genetically different from those sometimes brought back from overseas, suggesting that cutaneous leishmaniasis is endemic in the U.S. The researchers hope to improve detection of cases across the country by raising awareness that this is no longer a parasitic disease that is only picked up abroad.

During a presentation at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) on October 19, the researchers described their analysis of 2,133 tissue samples sent to the CDC for testing between 2005 and 2019. In their study, which has not yet been published, they found that most of the positive samples came from people who had traveled to countries where cutaneous leishmaniasis was endemic, but 86 people who were infected had not traveled outside the U.S.

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