Leishmaniasis Parasite Habitat Is Locally Advanced

DALLAS, Sept. 14 -- The natural habitat of the parasite that causes leishmaniasis, the so-called Baghdad boil, is creeping north, doctors here have warned.

Nine patients have been diagnosed with leishmaniasis in north Texas, way out of the parasite's normal range, according to Kent Aftergut, M.D., a clinical instructor of dermatology at the University of Texas Southwestern Medical Center and in private practice at Methodist Charlton Medical Center here.

Leishmaniasis is common in South America, Mexico and in the Middle East and many cases have been seen in troops returning from Iraq and Afghanistan. It has also been reported in south Texas.

But none of the nine patients here had traveled to areas where the parasite is endemic, leading Dr. Aftergut and colleagues to conclude they had acquired the disease locally.

Dr. Aftergut said he began to suspect something was amiss when a man from Waxahachie, south of Dallas, came to his office with sores that were refusing to heal and "looked clinically like leishmaniasis."

But because there had never been a report of locally acquired leishmaniasis and the man said he had not traveled in recent years, "we sort of ruled it out," Dr. Aftergut said.

Nevertheless, he said, he performed a biopsy and sent it to a pathologist to be cultured for the parasite, and the culture came back positive for Leishmania mexicana, a relatively benign parasite that affects only the skin.

Jolted by the discovery, Dr. Aftergut asked colleagues to look at their records, only to find another eight recent cases in the area around Dallas, in which none of the patients had traveled to endemic areas.

All of the patients had the relatively benign L. mexicana, he said.

"It makes skin sores, but the infection doesn't spread and become a full body disease like some of the others species of Leishmania," he said. "Usually, if patients have a normal immune system, the sores will resolve in six to 12 months and won't make the patients ill."

On the other hand, the sores are painful and most patients would prefer not to wait it out.

For L. mexicana - because the sores are localized - a treatment option is to remove the lesions surgically and follow up with an antifungal medication, Dr. Aftergut said.

Waiting "was not an option," for his patient, so Dr. Aftergut removed the lesions and treated the man for three months with fluconazole (Diflucan) to achieve a cure.

Other forms of leishmaniasis - especially those that affect internal organs, such as L. braziliensis - may require treatment with infusions of sodium stibogluconate.

But that medication has several potential adverse effects - it is phlebotoxic, can cause pancreatitis, and patients must be monitored by electrocardiogram during the infusion to guard against cardiac conduction disturbances. It can also cause nausea, vomiting diarrhea, and anaphylaxis, among other things.

"It's not easy to take," Dr. Aftergut said.

He said most clinicians would suspect leishmaniasis if they had a patient with non-healing sores that were negative on culture for a bacterial culprit - as long as the patient had recently traveled to an endemic area.

"Most doctors would know -- it even has a nickname, Baghdad boil," he said.

The implication of this outbreak is that doctors should be aware of the possibility, even if there's no obvious route of exposure. "You need to suspect it," he said.

The parasite is passed to humans by the bite of a sandfly and the animal vector is the burrowing wood rat, Dr. Aftergut said. People in rural areas may be more at risk, he added, but using insecticides, bug repellant and protective clothing may afford some protection.

A report of the outbreak has been submitted to the Journal of the American Academy of Dermatology, he said.