Visceral Leishmaniasis in Argentina: Molecular incrimination of the causative agent

LOCATELLI FM; MARCO JD; NEVOT MC; BARROSO PA; BARRIO AB; MORA MC; PARODI C; RUSSO P; ESTÉVEZ JO; BASOMBRÍO MA; HASHIGUCHI Y; KORENAGA M

Sensai

Congreso; The 51th Annual Meeting of Japanese Society of Tropical Medicine; 2010

Japanese Society of Tropical Medicine

Leishmaniasis is a zoonotic disease caused by several species of the intracellular protozoa of the genus Leishmania. A visceral form of this disease has been found throughout South America, mainly Brazil, where the main causative agent is Leishmania (Leishmania) chagasi (L. infantum), and dogs are considered the main reservoir host for this parasite. Contrary to this, visceral leishmaniasis has emerged in Argentina recently, although its detail has not been defined. In order to typify which species of Leishmania are involved in focus in North of Argentina, we applied the techniques of Nested PCR and sequencing of the cytochrome b (cyt b) gene of Leishmania using DNA templates directly purified from the node aspirated, the bone marrow or spleen from dogs previously diagnosed as positive by parasitological or serological methods. We analyzed 48 samples from dogs of Northeastern Argentina, mainly from Posadas, Misiones, while in province of Salta, Northwest Argentina, we analyzed 15 samples from dogs and one from a human patient. In Northeastern samples, 23 dogs (47.9%) were positive for cyt b. We identified two genotypes, LiA2 and LiA1. They were assigned to L. (L.) infantum, showing 99.9 to 100% homology to the reference strain of WHO MHOM/TN/80 / IPT1, when 817 base pairs were compared.  LiA1 was identified in 18 cases (78.3%), while LiA2 in five (21.7%). In the samples from the Northwest area, two dogs (13.3%) and one human patient were positive for cyt b, while three samples were identified as LiA2. Through nested PCR and sequencing of the cytochrome b gene techniques, L. (L.) infantum was incriminated as the causative agent of LCAN in the provinces of Misiones and Salta. This report is the first confirmation of the presence of visceral leishmaniasis in Northwestern Argentina in both humans and dogs. In addition, phylogenetic analysis of the cyt b gene suggests a closer relationship with the indigenous strains of the Old World than to those of L. (L.) chagasi in South America. Prospectively, it is necessary to develop techniques for sequencing multiple genes, as well as interdisciplinary collaboration to further studies such as the tracking of strains of parasites and transmission cycles involved in the area.