Leishmania infantum and Human Visceral Leishmaniasis, Argentina

Suggested citation for this article

Figure A1

Thumbnail of Incidence of visceral leishmaniasis (VL) in northern Argentina. Map at left indicates location of study area (right). Circle indicates location of farm where the patient (44-year-old man) in this study worked. Light green area indicates dry Chaco region, where VL is endemic and human cases have been found.

Figure A1. Incidence of visceral leishmaniasis (VL) in northern Argentina. Map at left indicates location of study area (right). Circle indicates location of farm where the patient (44-year-old man) in this study worked....

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 (Figure A1), 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 sandflies was also reported (2). Currently, 58 human VL cases have been reported in Posadas (3), and >7,000 infected dogs, Lu. longipalpis sandflies, 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 sandflies instead of Lu. longipalpis sandflies) (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 (Figure A1), 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 final diagnosis showed anemia, leukocytopenia, thrombocytopenia, and increased levels of lactate dehydrogenase. Results of urinalysis and coproculture were negative for parasites.
Electrophoresis of serum proteins showed increased levels of gamma globulins. The differential diagnosis was negative for malaria, mycosis, autoimmune hepatitis, and lymphoma. A bone marrow smear showed abundant amastigotes by Giemsa staining (Figure, panel A). The patient was treated with liposomal amphotericin B, 3 mg/day for 7 days, and recovered (8).

After a comprehensive interview, we verified that this patient had not been in the VL-endemic area in Argentina. However, he had worked (deforestation activities) during January–February 2009 on a farm in Finca Las Maravillas (22º3′29.30″S, 63º14′28.17″W), where he had been bitten by phlebotomines and acquired the disease. This farm was situated in the dry Chaco region near the border with Bolivia and Paraguay (zones with VL) (9), a region with intensive deforestation and agricultural activities.

For species identification, DNA was extracted from a bone marrow aspirate and peripheral blood. We amplified by nested PCR and sequenced the cytb gene (Figure, panel B) (6). The aligned 817-bp sequence obtained showed 100% homology with the cytb gene of the MHOM/TN/80/IPT1 L. (L.) infantum World Health Organization reference strain (Tunisian strain) and 99.3% homology with the MHOM/BR/74/PP75 L. (L.) chagasi strain (Brazilian strain) (7).

L. (L.) infantum was identified as the causative agent of this VL case in Salta, Argentina, where VL cases had not been seen for 50 years. Our findings indicate that this case was not caused by visceralization or a dermatropic Leishmania spp. We suggest that the scattered pattern of VL incidence in the dry Chaco region is caused by an enzootic cycle with accidental human transmission (5).

There are no reports of Lu. longipalpis sandflies in the study area or surrounding areas (10). Nevertheless, studies on natural infections of vector sandflies and reservoir-host animals (especially dogs) are needed. Therefore, the search for naturally infected sandflies and reservoirs of this infection should be intensified. Epidemiologic surveys of dogs are needed to identify spread of VL foci in areas of deforestation. Deforestation could alter vector and reservoir range and parasite density in the enzootic cycle and increase human exposure to infected vectors.

Alejandra Barrio

, Cecilia M. Parodi, Fabricio Locatelli, María C. Mora, Miguel A. Basombrío, Masataka Korenaga, Yoshihisa Hashiguchi, María F. García Bustos, Alberto Gentile, and Jorge D. Marco

Author affiliations: Universidad Nacional de Salta, Salta, Argentina (A. Barrio, C.M. Parodi, M.C. Mora, M.A. Basombrío, M.F. García Bustos, J.D. Marco); Kochi Medical School, Kochi, Japan (F. Locatelli, M. Korenaga, Y. Hashiguchi); Ministerio de Salud Pública-Provincia de Salta, Salta (A. Gentile)

Acknowledgments

We thank Servicio de Enfermedades Infecciosas-Hospital Señor del Milagro, Salta, Argentina, and Noemí Dávalo for support during the clinical phase of the study; Jesús Sajama for drawing the map; and Rubén Cardozo for conducting field research.
This study was supported in part by the El Consejo de Investigación de la Universidad Nacional de Salta and Comisión Nacional Salud Investiga-Ministerio de Salud de la Nación, Argentina.

References

Martín-Sánchez J, Navarro-Mari JM, Pasquau-Liaño J, Salomón OD, Morillas-Márquez F. Case report. Visceral leishmaniasis caused by Leishmania infantum in a Spanish patient in Argentina: what is the origin of the infection? BMC Infect Dis. 2004;4:20. DOIPubMed
Salomon O, Sinagra A, Nevot M, Barberian G, Paulin P, Estevez J, First visceral leishmaniasis focus in Argentina. Mem Inst Oswaldo Cruz. 2008;103:109–11. DOIPubMed
Cruz I, Acosta L, Gutiérrez MN, Nieto J, Cañavate C, Deschutter J, A canine leishmaniasis pilot survey in an emerging focus of visceral leishmaniasis: Posadas (Misiones, Argentina). BMC Infect Dis. 2010;10:342. DOIPubMed
Fernández MS, Salomón OD, Cavia R, Perez AA, Acardi SA, Guccione JD. Lutzomyia longipalpis spatial distribution and association with environmental variables in an urban focus of visceral leishmaniasis, Misiones, Argentina. Acta Trop. 2010;114:81–7. DOIPubMed
Salomón OD, Quintana MG, Bezzic G, Moránc ML, Betbederc E, Valdéz DV. Short communication: Lutzomyia migonei as putative vector of visceral leishmaniasis in La Banda, Argentina. Acta Trop. 2010;113:84–7. DOIPubMed
Myint CK, Asato Y, Yamamoto Y, Kato H, Bhutto AM, Soomro FR, Polymorphisms of cytochrome b gene in Leishmania parasites and their relation to types of cutaneous leishmaniasis lesions in Pakistan. J Dermatol. 2008;35:76–85. DOIPubMed
Foulet F, Botterel F, Buffet F, Morizot G, Rivollet D, Deniau M, Detection and identification of Leishmania species from clinical specimens by using a real-time PCR assay and sequencing of the cytochrome b gene. J Clin Microbiol. 2007;45:2110–5. DOIPubMed
Rosenthal E, Delaunay P, Jeandel PY, Haas H, Pomares-Estran C, Marty P. Liposomal amphotericin B as treatment for visceral leishmaniasis in Europe, 2009. Med Mal Infect. 2009;39:741–4. DOIPubMed
Bastrenta B, Mita N, Buitrago R, Vargas F, Flores M, Machane M, Human mixed infections of Leishmania spp. and Leishmania–Trypanosoma cruzi in a sub-Andean Bolivian area: identification by polymerase chain reaction/hybridization and isoenzyme. Mem Inst Oswaldo Cruz. 2003;98:255–64. DOIPubMed
Salomón OD, Rosa JR, Stein M, Quintana MG, Fernández MS, Visintin AM, Phlebotominae (Diptera: Psycodidae) fauna in the Chaco region and cutaneous leishmaniasis transmission patterns in Argentina. Mem Inst Oswaldo Cruz. 2008;103:578–84. DOIPubMed

Figures

Suggested citation for this article: Barrio A, Parodi CM, Locatelli F, Mora MC, Basombrío MA, Korenaga M, et al. Leishmania infantum and human visceral leishmaniasis, Argentina [letter]. Emerg Infect Dis [serial on the Internet]. 2012 Feb [date cited]. http://dx.doi.org/10.3201/eid1802.110924