While mosquitos have long been on the radar for transmitting diseases, there’s a new insect Americans need to be wary of: the sand fly. These minuscule tan flies, about a quarter the size of a mosquito, thrive in warm, rural, and forested areas. In various parts of the world, they are known carriers of a parasite responsible for leishmaniasis, an infectious disease.
Dr. Mary Kamb, a medical epidemiologist at the US Centers for Disease Control and Prevention (CDC), noted that many people don’t even realize they’ve been bitten by a sand fly. However, the aftermath can be severe. Leishmaniasis skin infections begin as a small bump, which later transforms into ulcerous sores days to weeks post-bite. These sores, often near the bite site, can be disfiguring, especially if they appear on the face.
The CDC’s recent study, presented at the annual meeting of the American Society of Tropical Medicine and Hygiene, analyzed over 2,100 skin samples from 2005 to 2019. Of these, 1,222 tested positive for leishmaniasis. While most were from individuals with a history of international travel, 86 samples were from patients who hadn’t traveled outside the US. The most common parasite detected was Leishmania mexicana.
Dr. Gideon Wasserberg, a professor at the University of North Carolina at Greensboro, emphasized the importance of this study. It confirms suspicions that leishmaniasis transmission is occurring in the US, a belief that has grown over the last 5 to 10 years. The parasite is believed to be carried by rats, and when sand flies bite these infected rats, they can acquire and subsequently transmit the parasite to humans.
For those in warm, rural areas, precautions are essential. Sand flies are deterred by DEET-containing bug sprays and can be killed by permethrin. Spraying camping gear and clothing is advisable. If a skin sore appears after a bug bite and doesn’t heal, seeking medical attention is crucial. Treatment for leishmaniasis involves a month-long regimen with medications like amphotericin B.
Wasserberg stressed the need for increased awareness, as many doctors in the US are unfamiliar with leishmaniasis. He stated, “Most doctors, if you ask them, ‘Is there leishmania in the U.S.?’ They’ll say ‘no way’ or ‘What is that?’”