Tropical Disease Leishmaniasis Has Been Found in Mainland U.S.

As if worrying about tick- and mosquito-borne diseases weren’t enough, now hunters have to worry about contracting diseases that were once only a concern in tropical locations.

According to NPR, leishmaniasis has joined other diseases in its spread to mainland U.S.

According to the World Health Organization (WHO), between 700,000 and one million new leishmaniasis cases are diagnosed each year — almost exclusively in tropical areas of the world, but recently a few cases have been diagnosed in the contiguous United States.

According to NPR, in 2014, a doctor in central Texas treated a 3-year-old boy with unusual bumps on his ear who tested positive for the parasitic disease.

“I was shocked,” said Bridget McIlwee, the doctor who saw the young patient, “because in medical school, we’re taught that this is a tropical disease, something that you see in immigrants, military returning from deployment, people who went on vacation to South America or Asia or Africa.”

After the diagnosis, McIlwee and her colleagues investigated the existence of leishmaniasis in the U.S., and published their findings in 2018. The Centers for Disease Control and Prevention (CDC) conducted its own investigation and found that the leishmaniasis parasite has likely been in the U.S. for years.

NPR says most of the U.S. cases have been reported in Texas, but Texas is the only state that requires reporting of the disease to health authorities, making the actual spread of the disease hard to track.

But Mary Kamb, a medical epidemiologist at CDC who worked on the new research, says, "The sand flies which have the capacity to transmit leishmaniasis exist in several U.S. states, primarily southern states."

McIlwee adds, "We have data supporting that the disease vectors and reservoirs have been located as far north as Ohio."

Leishmaniasis is mostly spread by sand flies, which live in wooded and grassland areas and primarily bite at dawn and dusk. According to the WHO, only a small percentage of people infected by the parasites that cause leishmaniasis will eventually develop the disease.

Leishmaniasis can be treated, but those treatments can cause issues.

“There are several [treatments], but they tend to be pretty severe and people may have side effects,” Kamb told NPR. “And if they need to take treatment by mouth, they tend to have a long treatment period of about 28 days.”

“There’s no effective vaccine against leishmaniasis, and there aren’t any drugs that people can take to prevent it,” she continued.

Taking precautions similar to those that protect against ticks and mosquitoes can help prevent sand fly bites, such as wearing clothing that covers the arms and legs and using insecticide.

As the planet continues to warm, new diseases are spreading to new areas of the world. Experts predicted in a recent report that the West Nile virus, typically found in warmer regions, will travel farther and become more common than ever.