Species diversity of Leishmania (Viannia) parasites circulating in an endemic area for cutaneous leishmaniasis located in the Atlantic rainforest region of northeastern Brazil.

OBJECTIVES: To identify the aetiological agents of cutaneous leishmaniasis and to investigate the genetic polymorphism of Leishmania (Viannia) parasites circulating in an area with endemic cutaneous leishmaniasis (CL) in the Atlantic rainforest region of northeastern Brazil. METHODS: Leishmania spp. isolates came from three sources: (i) patients diagnosed clinically and parasitologically with CL based on primary lesions, secondary lesions, clinical recidiva, mucocutaneous leishmaniasis and scars; (ii) sentinel hamsters, sylvatic or synanthropic small rodents; and (iii) the sand fly species Lutzomyia whitmani. Isolates were characterised using monoclonal antibodies, multilocus enzyme electrophoresis (MLEE) and polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer region rDNA locus. RESULTS: Seventy-seven isolates were obtained and characterised. All isolates were identified as Leishmania (Viannia) braziliensis serodeme 1 based on reactivity to monoclonal antibodies. MLEE identified 10 zymodemes circulating in the study region. Most isolates were classified as zymodemes closely related to L. (V.) braziliensis, but five isolates were classified as Leishmania (Viannia) shawi. All but three of the identified zymodemes have so far been observed only in the study region. Enzootic transmission and multiclonal infection were observed. CONCLUSIONS: Our results confirm that transmission cycle complexity and the co-existence of two or more species in the same area can affect the level of genetic polymorphism in a natural Leishmania population. Although it is not possible to make inferences as to the modes of genetic exchange, one can speculate that some of the zymodemes specific to the region are hybrids of L. (V.) braziliensis and L. (V.) shawi.

Persistence of leishmania parasites in scars after clinical cure of American cutaneous leishmaniasis: is there a sterile cure?

BACKGROUND: It is uncertain whether Leishmania parasites ever disappear after clinical cure of American cutaneous leishmaniasis (ACL). Recently, sensitive molecular techniques have allowed the identification of Leishmania parasites directly in specimens from patients' scars. METHODS: Scars of 32 patients from northeastern Brazil who were treated and clinically cured of ACL were analyzed by use of polymerase chain reaction (PCR), culture, and histopathologic examination. RESULTS: DNA specific for Leishmania (Viannia) was detected in scars of 30 (93.7%) of 32 patients. In specimens from 3 of the scars, Leishmania parasites could be isolated by culture; PCR results also were positive for those 3 specimens. No parasites were found by histopathologic examination, and fibrotic alterations were present in all cases, with slight inflammatory foci observed in 4 of the cases studied. CONCLUSIONS: The results suggest that clinical cure of ACL is rarely associated with sterile cure. The implications of persistence of parasites for the clinical evolution, relapse, and transmission of leishmaniasis deserves further studies, particularly with the increasing incidence of coinfection with leishmaniasis and acquired immunodeficiency syndrome.