October 20, 2023 – A parasitic skin disease spread by sand flies, once associated only with international travel, isn't any longer considered an “imported” disease within the United States
The disfiguring disease attributable to sandfly bites, called cutaneous leishmaniasis, has now evolved right into a form found only within the southern United States. The disease could be difficult to diagnose. It was once so rare that it was often not considered possible when diagnosed. According to the study, it could actually also mimic other diseases resembling leprosy, skin cancer and fungal skin diseases CDCwho discussed the subject on the American Society of Tropical Medicine and Hygiene (ASTMH) annual meeting in Chicago this week.
Cutaneous leishmaniasis has been diagnosed in 86 people within the United States over the past decade who had not traveled abroad, the CDC researchers reported. Using genetic sequencing tools, they analyzed tissue samples from infected people and located that the non-travellers had a novel version of the disease, meaning it was spread by local fly populations.
“There was already evidence of local transmission based on a small number of case reports, but now for the first time we have a clear genetic fingerprint from a relatively large group, providing further evidence that leishmaniasis may be well established in some cases. “Parts of the United States,” said Mary Kamb, MD, MPH, of the Division of Parasitic Diseases and Malaria at the CDC's National Center for Emerging and Zoonotic Infections in a opinion. “While most of these infections occurred in people in Texas, sand flies that can transmit leishmaniasis exist in many parts of the country, and particularly in the southern United States.”
The risk of sandfly bites is biggest at dusk and at night when the insects are feeding. The disease could cause quite a lot of skin problems, including large nodules or plaques that sometimes appear weeks or months after infection. Wounds from the disease can change in appearance and size over time, becoming open wounds with a raised edge and a central crater or ulcer which may be covered with crust or scales, based on the CDC. Even without treatment, most wounds eventually heal, even in the event that they last for months or years. The resulting scarring is disfiguring.
Scientists fear that a deadlier type of the disease called visceral leishmaniasis, which can also be transmitted by sand flies, might be gaining a foothold within the United States. The flies feed on imported dogs, which carry a parasite called “ Leishmania in infants. According to a press release from the ASTMH, the disease affects internal organs and kills between 20,000 and 30,000 people worldwide each year.
A veterinarian and infectious disease expert said a million dogs are imported into the U.S. each year and many are not properly screened for infectious diseases.
“Dogs are the primary host of this disease, and dogs are now regularly entering the United States that have lived in areas where leishmaniasis parasites are circulating in animals and humans,” said Christine Petersen, DVM, PhD, director of the Center for Emerging Infectious Diseases on the University of Iowa, based on ASTMH. “That’s why we need a better system to protect against the risk of introduction in the United States.” Leishmania in infantsone in every of the deadliest tropical parasites on this planet, into U.S. sandfly populations.”