A flesh-eating parasite once thought to concern only those in tropical locales is now "endemic" in the US. Leishmania mexicana is believed to be spreading through sand flies in the southern US, particularly Texas, according to an analysis from the Centers for Disease Control and Prevention. The parasite triggers the disease leishmaniasis, of which there are three forms. Cutaneous leishmaniasis, the most common, is accompanied by skin lesions that can lead to life-long scarring and disability. CDC medical epidemiologist Dr. Mary Kamb and colleagues have now identified leishmaniasis in tissue samples collected between 2005 and 2019 from various patients who said they hadn't left the US, per CBS News.
The genetic information, part of a new study presented Thursday at the annual meeting of the American Society of Tropical Medicine and Hygiene, "adds credence to this idea that leishmaniasis is occurring here in the United States, it's endemic here in the United States, at least in Texas and maybe southern border states," Kamb, a study co-author, tells CBS. The parasite showed slight genetic changes in about 50 cases, including at least one case each year. "Those two snips, those two polymorphisms in the sequence, are very distinct between those who reported travel history compared to those who did not," CDC microbiologist Vitaliano Cama tells CBS.
There is no vaccine available for leishmaniasis, which has also been found in Oklahoma and Arizona, per Bloomberg. Certain drugs are used in treatment but there is "low certainty" about their effectiveness and some patients who respond to treatment later suffer a relapse, per CBS. That's why experts say it's important to raise awareness of the disease, which is not well recognized outside of Texas. Controlling sand flies is a gigantic task as the tiny tan-colored flies, most active at night, don't need standing water to breed and are about a quarter of the size of a mosquito, meaning they can slip through window screens and mosquito nets. "Sometimes you don't even notice that you've been bitten," Kamb tells CNN.
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Leishmaniasis infections may begin with a small bump that erupts into ulcerous sores days or weeks later. As the parasite damages nerves in the skin, the sores may not be particularly painful. A more severe form of the disease, visceral leishmaniasis, spread through the leishmania infantum parasite, "is fatal if left untreated in over 95% of cases," according to the World Health Organization. It is not believed to be transmitted in the US, per CNN. However, experts fear that could change after years of dogs arriving from abroad. Dogs are considered the main host of the parasite. (More flesh-eating infection stories.)
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