The surveillance of prevalent Leishmania and sand fly species in endemic areas is important for prediction of the risk and expansion of leishmaniasis. In this study, we developed a polymerase chain reaction (PCR)-based method for detection of Leishmania minicircle DNA within individual sand flies. Using this method, we detected minicircle DNA in 6 (3.3%) of 183 sand flies, while 5 (3.5%) of 143 were positive for Leishmania promastigotes in the same areas by microscopic examination. The species were identified as Leishmania (Leishmania) mexicana by nucleotide sequencing of the cytochrome b gene. Additionally, all the Leishmania-positive sand flies were identified as Lutzomyia ayacuchensis by the restriction enzyme digestion of the PCR-amplified 18S ribosomal RNA gene fragments. Since this combined method is relatively easy and can process a large number of samples, it will be a powerful tool for the rapid identification of prevalent sand fly and Leishmania species as well as monitoring the infection rate in sand fly populations in endemic areas.

Congenital Trypanosoma cruzi infection is a highly pathogenic and underreported condition. Early recognition is essential for effective treatment. Umbilical chord blood from newborns (n = 302) to infected mothers was analyzed with microhematocrit, hemoculture, and PCR methods. Each subject was then followed serologically. In calibrated suspensions of T. cruzi in blood, the sensitivity of PCR was 27-fold higher than hemoculture. However, this advantage was not reflected during routine testing of samples from maternities, partly because of the uneven distribution of few parasites in small samples. Levels of detection of congenital infection were 2.9% (8/272) for microhematocrit, 6.3% (18/287) for hemoculture, 6.4% (15/235) for PCR, and 8.9% (27/302) for cumulated results. Evaluation against the standard of delayed serology indicates that the regular application of PCR, hemoculture, and microhematocrit to blood samples allows the rapid detection of about 90% of the congenitally infected newborns, in samples that can be obtained before the mother and child leave the maternity ward.

We studied the seroprevalence of antibodies against Trypanosoma cruzi in the human population along with domiciliary infestation by triatomine bugs in an area endemic for Chagas disease in the Chaco Province of Argentina. In addition, we carried out parasitologic surveys in patients, dogs, wild mammals, and vectors. The mean seroprevalence in humans was 27.81% (109 of 392) and 24.14% (63 of 261) in 1–15-year-old children. The minimum domiciliary infestation rate was 13.33%, with certain areas reaching 53.85%. The prevalence was 15.09% (16 of 106) in dogs and 35.71% (10 of 28) in opossums. Infection with T. cruzi was detected in 30.10% (59 of 196) of the Triatoma infestans tested. Compared with nationwide studies, our data suggest that 1) there are zones requiring immediate sanitary action, and 2) nationwide estimates are based on very heterogeneous epidemiologic situations. This heterogeneity emphasizes the importance of in-depth studies of restricted areas to provide additional information for a better understanding of the present status of Chagas disease in Argentina.

Chagas Disease, caused by the protozoan Trypanosoma cruzi, is a major health and economic problem in Latin America for which no vaccine or appropriate drugs for large-scale public health interventions are yet available. Accurate diagnosis is essential for the early identification and follow up of vector-borne cases and to prevent transmission of the disease by way of blood transfusions and organ transplantation. Diagnosis is routinely performed using serological methods, some of which require the production of parasite lysates, parasite antigenic fractions or purified recombinant antigens. Although available serological tests give satisfactory results, the production of reliable reagents remains laborious and expensive. Short peptides spanning linear B-cell epitopes have proven ideal serodiagnostic reagents in a wide range of diseases. Recently, we have conducted a large-scale screening of T. cruzi linear B-cell epitopes using high-density peptide chips, leading to the identification of several hundred novel sequence signatures associated to chronic Chagas Disease. Here, we performed a serological assessment of 27 selected epitopes and of their use in a novel multipeptide-based diagnostic method. A combination of 7 of these peptides were finally evaluated in ELISA format against a panel of 199 sera samples (Chagas-positive and negative, including sera from Leishmaniasis-positive subjects). The multipeptide formulation displayed a high diagnostic performance, with a sensitivity of 96.3% and a specificity of 99.15%. Therefore, the use of synthetic peptides as diagnostic tools are an attractive alternative in Chagas’ disease diagnosis. Chagas disease, caused by the parasite Trypanosoma cruzi, is a life-long and debilitating illness of major significance throughout Latin America, and an emergent threat to global public health. Diagnostic tests are key tools to support disease surveillance, and to ultimately help stop transmission of the parasite. However currently available diagnostic methods have several limitations. Identification of novel biomarkers with improved diagnostic characteristics is a main priority. Recently, we conducted a large-scale screening looking for new T. cruzi antigens using short peptides displayed on a solid support at high-density. This led to the identification of several hundred novel antigenic epitopes. In this work we validated the serodiagnostic performance of 27 of these against an extended panel of human serum samples. Based on this analysis, we developed a proof-of-principle multiplex diagnostic kit by combining different validated reactive peptides. Overall, our data support the applicability of high-density peptide microarrays for the rapid identification and mapping epitopes that could be readily translated into novel and useful tools for diagnosis of Chagas disease.