Leishmania infantum and Human Visceral Leishmaniasis, Argentina

To the Editor: In Argentina, 14 autochthonous human cases of visceral leishmaniasis (VL) were reported during 1925–1989. These cases occurred in different localities in Salta, Jujuy, Santiago del Estero, and Chaco Provinces of northwestern Argentina (online Appendix Figure, wwwnc.cdc.gov/EID/article/18/2/11-0924-FA1.htm), where cutaneous leishmaniasis (CL) caused principally by Leishmania (Viannia) braziliensis is endemic. It had been postulated that scattered/sporadic VL cases could be caused by visceralization of dermatrophic Leishmania spp. because of 1) absence of already recognized L. (Leishmania) infantum vector species; 2) geographic overlap with the region where CL is endemic; 3) simultaneous symptoms of CL; or 4) lack of detailed parasitic characterization at the molecular level for cases of suspected VL (1). However, during recent decades, urban outbreaks of VL have spread to southern regions of South America (Mato Grosso do Sul, Brazil, and Asunción, Paraguay) near the northern border with Argentina. In May 2006, an autochthonous human case of VL was reported in Posadas (northeastern Argentina); it was associated with the canine visceral form of the disease. In addition, the presence of Lutzomyia longipalpis sandfl ies was also reported (2). Currently, 58 human VL cases have been reported in Posadas (3), and >7,000 infected dogs, Lu. longipalpis sandfl ies, and canine VL have been found 350 km south of Posadas (4). During 2007–2008, new VL cases in 4 children and 7 dogs were reported clustering in time and space in La Banda-Santiago del Estero in the dry Chaco region of Argentina. This focus showed a different pattern from that found in the only urban outbreak of VL reported (nearly the same number of cases in humans and dogs, and the suspected vector was Lu. migonei sandfl ies instead of Lu. longipalpis sandfl ies) (5). We report a case of autochthonous human VL in Salta Argentina that was caused by L. (L.) infantum. This parasite was characterized by cytochrome b (cytb) gene sequencing. Sequencing of this gene has been validated for precise characterization of Leishmania spp. (6,7). On September 9, 2009, a 44-year-old man from Salta, Argentina (online Appendix Figure), was admitted to the Infectious Disease Service at Hospital Señor del Milagro in Salta. The patient had fever, weight loss, dyspepsia, and splenomegaly that evolved over 3 weeks. Physical examination showed cutaneous and mucosal paleness. His general condition was feverish and rapidly deteriorating. Laboratory tests at the time of fi nal diagnosis showed anemia, leukocytopenia, thrombocytopenia, and increased levels of …