Natural infection of Lutzomyia neivai with Leishmania spp. in northwestern Argentina.

The natural infection of Lutzomyia neivai with Leishmania in the endemic area of American cutaneous leishmaniasis (ACL) in northwestern Argentina was analyzed by the polymerase chain reaction (PCR)-hybridization technique. Phlebotominae sand flies were captured in the provinces of Tucumán and Salta between 1999 and 2003. From a sample of 440 Lu. neivai females analysed for the detection of the Leishmania (Viannia) and Leishmania (Leishmania) subgenera, 9.1% of the samples resulted infected with a parasite of the subgenus Viannia and none with the Leishmania. This is the first report of naturally infected sand flies in Argentina besides the first report of infected Lu. neivai sensu strictu. Our results contributed to further incrimination of this specie as vector of leishmaniasis in the area and the identification of the main circulating parasite as belonging to the Leishmania (Viannia) subgenera.

Detection of Leishmania braziliensis in human paraffin-embedded tissues from Tucumán, Argentina by polymerase chain reaction.

American cutaneous leishmaniasis (ACL) is an endemic disease in Northern Argentina. We applied the polymerase chain reaction (PCR) followed by a hybridization labelled probe to 21 paraffin embedded human skin biopsies, already analyzed histologically, from leishmaniasis endemic areas in the province of Tucumán, Argentina. We used primers previously designed to detect a Leishmania-specific 120-base-pair fragment of kinetoplast DNA minicircle, other two primer pairs that amplify kDNA minicircles belonging to the L. braziliensis and L. mexicana complexes respectively, and specific oligonucleotide primers to detect L. (V.) braziliensis which amplify the sequence of the ribosomal protein L-14 of this species. The PCR-hybridization showed a sensitivity of 90.5% when compared to the histopathology test which was 61.9%. Five of the total samples analyzed were positive for the L. braziliensis complex whilst none was positive for the L. mexicana complex. The specific primers for L. (V.) braziliensis detected the parasite in four samples. These results are consistent with those reported for close endemic areas and demonstrate that the causative agent of human leishmaniasis in the analyzed cases was L. (V.) braziliensis. PCR should be used as a diagnostic tool for tegumentary leishmaniasis, especially in the mucosal form, and as a valuable technique for the identification of the Leishmania species that causes the disease in certain areas.