Characterization of human infection by Leishmania spp. in the Northwest of Argentina: immune response, double infection with Trypanosoma cruzi and species of Leishmania involved

Abstract

The aims of this study were to characterize human American tegumentary leishmaniasis, which includes cutaneous, mucocutaneous and mucosal leishmaniasis, in Northwest Argentina, to determine the prevalence of double infection with Trypanosoma cruzi and to identify the species of Leishmania in this area. Most of the 330 leishmaniasis patients presented cutaneous ulcers (96.1%), 2.4% mucocutaneous and 1.5% the mucosal form ('espundia'). The aetiological agents, determined by isoenzyme electrophoresis, were identified as Leishmania (Viannia) braziliensis in 16 out of 20 isolates and in the remaining 4 as Leishmania (Leishimania) amazonensis, the first ever-documented in Argentina. Sera analysed by ELISA and IFA using complex antigen from both T. cruzi and L. braziliensis showed a very high percentage of positives (66.3-78.2%). When antigens for specific diagnosis of Chagas' disease were used, 40.9% of the leishmaniasis patients were also found to be infected by T. cruzi. These results indicate that the strong immune response against T. cruzi gave no protection to Leishmania, in spite of the serological cross-reaction between these parasites. In addition, we showed that more than 40% of the patients would be misdiagnosed as chagasic if complex antigens, as epimastigotes or soluble fraction from epimastigotes, were used in IFA or ELISA. This is of paramount importance not only because patients' treatment would be associated to misdiagnosis but the fact that in many countries in Central and South America, a positive test for Chagas' disease means a rejection for those seeking employment.

Field Evaluation of a Rapid Immunochromatographic Assay for Detection of Trypanosoma cruzi Infection by Use of Whole Blood

“…when conventional assays are used for the diagnosis of Chagasic infections (8,19). This phenomenon may have accounted for some or all of the eight false-negative individuals.…”

Evaluation of Serological Tests To Identify Trypanosoma cruzi Infection in Humans and Determine Cross-Reactivity with Trypanosoma rangeli and Leishmania spp

“…Cross-reactivity between sera of patients infected with T. cruzi and sera of patients infected with Leishmania spp. in the serodiagnosis of Chagas' disease is well documented (2,20). In some areas of endemicity in Central America and Brazil, where T. cruzi and the nonpathogenic protozoan Trypanosoma rangeli can be found infecting the same vectors and vertebrate hosts (12,14), cross-reactivity has been the subject of discussion.…”

Restricted Outbreak of American Tegumentary Leishmaniasis with High Microfocal Transmission

“…All were treated with meglumine antimoniate at 10 mg/kg/day for 21 to 28 days, the standard practice in the area, which has demonstrated a short term efficacy 95% in observational and pilot randomized prospective studies. 6,17 The patient presenting with MCL required two cycles of meglumine antimoniate followed by a 28-day cycle of amphotericin-B deoxycolate to achieve full clinical resolution. The patient with lesions on his thorax and face (#2 in Tables 1 and 2) required a second cycle of meglumine antimoniate followed by a course of oral azithromycin for 4 weeks to achieve clinical cure.…”

“…Induration was read 48 to 72 hours later, and a diameter of 5 mm was considered positive. 17 Enzyme-linked immunosorbent assay (ELISA). Serologic response was evaluated by ELISA with protein homogenate from promastigotes of L. guyanensis.…”