Leishamania mexicana, a flesh-eating parasite that was once only a danger to travelers, is believed to be spreading locally in the southern U.S. through sand flies, according to CDC scientists.
After an infected fly bites an individual, it can take several weeks to months for skin sores to erupt. The lesions can then last for several years, after which they leave a noticeable scar.
While there is no vaccine available, hospitals do have drugs for the disease caused by the flesh-eating parasite. Fortunately, not all cases require medical treatment.
Officials say the parasite is now “endemic” in many southern states, including Texas. According to Dr. Kamb, who is part of the CDC Parasitic Diseases and Malaria Division, “the genetic information supports the idea that [the parasite] is occurring in the U.S.” She was also a co-author of the new study, which was released on Thursday.
Previously, the parasite has been seen in Americans who have not done any international travel. In fact, the World Health Organization already has cutaneous leishmaniasis listed as “endemic” in the U.S.
A Unique Genetic Fingerprint
During the diagnosis process, doctors typically take biopsies from the infected lesions, from which samples are taken. They are then sent to the CDC lab – the only lab outside the military that’s capable of testing for the parasite up until 2020.
The scientists found that many of the patients who were infected with the parasite but have not traveled internationally were infected by Leishmania Mexicana. Among these, approximately 50 were infected by a parasite strain that had a ‘unique’ set of genetic changes, that set them apart from the original strain.
How the Parasite Spreads
Leishmaniasis, like other ‘vector-borne’ diseases, can be difficult to control as it requires stamping out the bugs that transmit the infection to humans. Other animals that can act as a ‘reservoir’ for the parasite (e.g. rodents), also pose a risk.
Compared to larger insects, sandflies can be difficult to control as they are one-fourth the size of mosquitos. They also don’t require stagnant water to breed.
According to the World Health Organization, the flesh-eating parasite infects up to a million individuals every year. In the Americas, most of the cases are seen in Brazil, though they have also become more common in Latin America.
In the United States, leishmaniasis it not ‘reportable’ in most states, which limits the CDC’s ability to track case numbers.
An Even Deadlier Parasite Can be Transmitted from Dogs
Leishmania infantum is a deadlier cousin that causes a more severe form of the disease. Without prompt medical treatment, over 90 percent of patients will die.
Symptoms include weight loss, fever, and swelling of the spleen and liver.
In countries where visceral leishmaniasis is seen, dogs are one of the “main reservoirs’. A recent boom in dog arrivals from travel, moving, or adoptions, has also raised concerns about its spread.
Some cases of leishmania infantum have also been seen in dogs who have not traveled internationally. Not only can they give the parasite to sand flies, but the canines can also spread the parasite directly to humans through bites.