Epidemiological patterns of cutaneous leishmaniasis in Panama. II. Incidental occurrence of cases in non-endemic settlements.

Epidemiological studies on cutaneous leishmaniasis were carried out in a settlement in the Bayano region, Republic of Panama, during 1971-72. This settlement was established about 12 years earlier for the purpose of cattle raising by small groups of settlers. The primary forest was cut and cleared and the area planted with grass. The presence of active cases of cutaneous leishmaniasis among humans and animals, both domestic and ferals, was investigated. In addition, phlebotomine sandflies were collected to determine their species composition. In 1971, nine of the 161 persons interviewed had active lesions; all but one of the patients were males and of these seven were adults. Five (9%) of 55 dogs and one (3%) of 33 feral mammals examined also were found infected. Strains of the parasite infecting both humans and animals were characterized as Leishmania braziliensis. About 60% of the sandflies collected belong to four man-biting species previously incriminated as vectors of human cutaneous leishmaniasis in Panama. The extensive pasture, together with periodic applications of insecticides in the houses by the antimalarial agency in this country, provided an effective barrier against transmission within the settlement itself. However, both humans and dogs acquired the disease during excursions into the surrounding forest. No new cases were found in 1972.