Autochthonous visceral leishmaniasis: a report of a second case in Thailand.

Visceral leishmaniasis (VL) is a rare disease in Thailand. Only one previous case has been reported in which transmission was likely autochthonous. We conducted an investigation of a case of VL, which included serological and symptom surveys of people who lived near the case in Nan Province and Bangkok, serological surveys of domestic animals in his home village and sand fly surveys in his home village and in Bangkok. No humans interviewed met our case definition for possible VL. One hundred thirty-one villagers were seronegative for Leishmania antibodies. We found three cows and one cat that had positive direct agglutination tests for Leishmania spp, but we were unable to confirm current infection by PCR. Sand fly surveys showed that most of the flies were of the Sergentomyia genus, which has not previously been reported as a competent vector in Thailand. Nonetheless, we conclude, based on the patient's lack of travel outside Thailand and the presence of seropositive domestic animals in his home village, that he was most likely infected by the bite of a sand fly in Thailand. We believe this is the second case of autochthonously transmitted VL in Thailand.