CDC: Skin Ulcer Parasite Infection Spreading

New strains of leishmania, a parasitic disease that starts with skin ulcers, are spreading. The CDC reports on an outbreak in a group of 24 scientists and warns US physicians to be alert for the infection in travelers returning from Latin America and South America. The destruction of the Amazon rain forest may be playing a role.

An outbreak of a Brazilian strain of cutaneous leishmaniasis (CL) in French Guiana among 24 visiting scientists has alarmed tropical disease experts at the US Centers for Disease Control and Prevention (CDC).

The CDC alerts US physicians to be aware of possible infection in travelers returning from the region. They also note that this strain responds differently to treatment than other strains. The disease is caused by a protozoan parasite and transmitted by the bite of the sand fly.

“The geographic extension of and numeric increase in L. braziliensis cases in the Guiana ecoregion complex, as observed in the rest of South America, are worrisome, and continuous epidemiologic surveillance is needed,” Guillaume Martin-Blondel, MD and colleagues at Toulouse University Hospital in Toulouse, France, wrote this month in the CDC’s Emerging Infectious Disease journal.

CL infection with L. braziliensis “is emerging and has potential to disseminate,” the team wrote.

The scientists, a multi-national group, were on a field mission in Saul, French Guiana in the Amazonian rainforest. Seven came down with symptoms a mean period of 19 days after they returned home.

The disease results in ulcers mostly on lower limbs but also on upper limbs and ears. It can also cause nodular lymphangitis, adenitis, and superficial phlebitis. It can also cause ulcers in the mucous membranes of the lips, nose, soft palate or larynx.

Infection is confirmed by microscopic examination of skin scrapings to look for typical amastiotes, or by a positive Leishmania species PCR result. Treatment is intramuscular meglumin antimoniate or intravenous liposomal amphotericin B. The Brazilian strain does not respond to pentamidine isethionate, the first-line treatment for another strain, L. guyanensis CL.

“Leishmaniasis is increasingly seen among travelers returning from Latin American countries, particularly from Bolivia, Belize and French Guiana,” the CDC noted. The transmission cycle of the parasitic disease involves reservoir hosts including dogs and rodents and is spread by sand fly vectors. “Changing human activities that affect these factors may have resulted in the emergences of species with distinct pathogenic potentials and responses to therapy,” the authors wrote. Until this outbreak, L. braziliensis infection had been seen only in Argentina, Brazil, Panama and Venezuela.

An increase in tourism and more development of the Amazon rain forest could be to blame for the spread of the infection, the team wrote.