CDC Warns of Local Sand Fly-Transmitted Parasitic Disease with Potential Disfiguring Effects

A recent study by the U.S. Centers for Disease Control and Prevention (CDC) has revealed that a skin disease, previously mainly associated with international travelers returning to the United States, is now being identified among Americans who have not traveled abroad.

Leishmaniasis, a parasitic disease transmitted through sand fly bites, was traditionally detected in individuals coming from tropical, subtropical, and southern European regions.

However, according to an October 19 press release from the American Society of Tropical Medicine and Hygiene (ASTMH), the CDC’s research shows that Americans with no travel history have also contracted the disease. The infections among these individuals are caused by Leishmania parasites that differ from the “imported” cases.

Presented at the annual ASTMH meeting on October 19, this study emerged due to a noticeable increase in cutaneous leishmaniasis infections in the United States over the past decade. This form of leishmaniasis, which primarily affects the skin, results in enduring skin lesions that can last for months or even years.

The CDC study revealed that the majority of cases were individuals who had traveled to regions where leishmaniasis is prevalent.

However, in the case of 86 patients with no travel history, an examination of tissue samples indicated that the Leishmania strain responsible for their infections had a “slightly distinct genetic signature.” This finding suggested that these infections were attributed to an American variant, transmitted by local sand fly populations.

The majority of infections among non-travelers were identified in individuals residing in Texas, as reported by Mary Kamb, who works in the division of parasitic diseases and malaria at the CDC’s National Center for Emerging and Zoonotic Infections. Nevertheless, she emphasized that sand flies capable of transmitting leishmaniasis are not limited to Texas but are found throughout the United States, particularly in the southern regions.

The increasing number of cutaneous leishmaniasis cases in the United States is raising concerns about the potential spread of the deadly form of the infection, visceral leishmaniasis, primarily through imported dogs carrying the pathogen.

Visceral leishmaniasis represents the most lethal variant of this infection, with a mortality rate exceeding 95% if left untreated, as per the World Health Organization. It can affect internal organs and claims the lives of 20,000 to 30,000 individuals globally each year.

Unfortunately, there are no drugs for preventing the disease, and while some medications can be used to treat human infections, they may result in severe side effects. In contrast, vaccines for dogs are available in Brazil and Europe.