No abstract

Leishmaniases are tropical zoonotic diseases, caused by kinetoplastid parasites from the genus Leishmania. New World (NW) species are related to sylvatic cycles although urbanization processes have been reported in some South American Countries such as Colombia. Currently, few studies show the relative distribution of Leishmania species related to cutaneous Leishmaniasis (CL) in South America due to the lack of accurate surveillance and public health systems. Herein, we conducted a systematic estimation of the Leishmania species causing CL in Colombia from 1980 to 2001 via molecular typing and isoenzymes. A total of 327 Leishmania isolates from humans, sandflies and reservoirs were typed as L. panamensis 61.3% (201), L. braziliensis 27.1% (88), L. lainsoni 0.6% (2), L. guyanensis 0.9% (3), L. infantum chagasi 4% (12), L. equatoriensis 0.6% (2), L. mexicana 2.1% (8), L. amazonensis 2.8% (9) and L. colombiensis 0.6% (2). This is the first report of two new Leishmania species circulating in Colombia and suggests the need to convince the Colombian government about the need to deploy and standardize tools for the species identification to provide adequate management to individuals suffering this pathology.

Blastocystis is a common enteric protist colonizing probably more than 1 billion people with a large variety of non-human hosts. Remarkable genetic diversity has been observed, leading to the subdivision of the genus into multiple subtypes (ST), some of which are exclusively found in non-human hosts. The aim of this study was to determine the distribution of Blastocystis STs/18S alleles in symptomatic (abdominal pain, anal pruritus, diarrhea, headache, nauseas and/or vomit) and asymptomatic children from nine geographical regions of Colombia. A total of 2026 fecal samples were collected as part of a national survey to estimate the frequency of intestinal parasites in children. A set of 256 samples that were Blastocystis positive was finally selected. The samples were submitted to DNA extraction, Real Time PCR and sequencing using Blastocystis-specific primers targeting the small subunit rRNA gene for ST identification. DNA of Ascaris lumbricoides (16.4%), Trichuris trichiura (8.2%), hookworms (Necator americanus/Ancylostoma duodenale) (7.3%), Giardia duodenalis (23.1%), Entamoeba complex (82%), Entamoeba coli (55%), Hymenolepis nana (0.8%), Endolimax nana (33.2%) and Neobalantidium coli (2.7%) was detected in the Blastocystis-positive samples. We detected ST1 (21.4%), ST2 (19.5%), ST3 (55.5%), ST4 (0.8%), ST6 (2%) and ST7 (0.8%); alleles 1, 2, 4, 81, 82 and 83 for ST1; alleles 9, 11, 12, 15, 67, 71 and 73 for ST2; alleles 34, 36, 38, 45, 49, 55, 134 and 128 for ST3; allele 42 for ST4; allele 122 for ST6, and allele 142 for ST7. Further studies implementing high-resolution molecular markers are necessary to understand the dynamics of Blastocystis transmission and the role of this Stramenopila in health and disease.

BackgroundThe diagnosis of Chagas disease is complex due to the dynamics of parasitemia in the clinical phases of the disease. The molecular tests have been considered promissory because they detect the parasite in all clinical phases. Trypanosoma cruzi presents significant genetic variability and is classified into six Discrete Typing Units TcI-TcVI (DTUs) with the emergence of foreseen genotypes within TcI as TcIDom and TcI Sylvatic. The objective of this study was to determine the operating characteristics of molecular tests (conventional and Real Time PCR) for the detection of T. cruzi DNA, parasitic loads and DTUs in a large cohort of Colombian patients from acute and chronic phases.Methodology/Principal FindingsSamples were obtained from 708 patients in all clinical phases. Standard diagnosis (direct and serological tests) and molecular tests (conventional PCR and quantitative PCR) targeting the nuclear satellite DNA region. The genotyping was performed by PCR using the intergenic region of the mini-exon gene, the 24Sa, 18S and A10 regions. The operating capabilities showed that performance of qPCR was higher compared to cPCR. Likewise, the performance of qPCR was significantly higher in acute phase compared with chronic phase. The median parasitic loads detected were 4.69 and 1.33 parasite equivalents/mL for acute and chronic phases. The main DTU identified was TcI (74.2%). TcIDom genotype was significantly more frequent in chronic phase compared to acute phase (82.1% vs 16.6%). The median parasitic load for TcIDom was significantly higher compared with TcI Sylvatic in chronic phase (2.58 vs.0.75 parasite equivalents/ml).Conclusions/SignificanceThe molecular tests are a precise tool to complement the standard diagnosis of Chagas disease, specifically in acute phase showing high discriminative power. However, it is necessary to improve the sensitivity of molecular tests in chronic phase. The frequency and parasitemia of TcIDom genotype in chronic patients highlight its possible relationship to the chronicity of the disease.

; Universidad Antonio Nariño (UAN), Bogotá, Colombia o Chagas disease is one of the main public health issues in Latin America. Increasingly during the past few decades, Trypanosoma cruzi infection has been detected in North America, Europe, and the Western Pacific, mainly as a result of population movement. The limited availability of rapid serological diagnostic tests hinders rapid diagnosis and early treatment in areas of endemicity and nonendemicity. In collaboration with 11 national reference laboratories (NRLs) from different geographical areas, we evaluated the performances of commercialized serological rapid diagnostic tests (RDT) for T. cruzi infection. Eleven commercialized T. cruzi infection RDTs were evaluated on a total of 474 samples extensively tested with at least three different techniques for Chagas disease, maintained at controlled low temperatures, and stored in the serum banks of the 11 NRLs. We measured the sensitivity, specificity, and concordance of each RDT and provided an additional questionnaire to evaluate its ease of use. The selected RDTs in this study were performed under controlled laboratory conditions. Out of the 11 RDTs, we found 8 of them to be useful, with the cassette format favored over the strip. We did not observe significant differences in RDT performances in the different regions. Overall, the performance results were lower than those disclosed by the manufacturers. The results of this evaluation validate the possibility of using RDTs to diagnose Chagas disease, thereby decreasing the time to treatment at a primary health care facility for patients who are willing to be treated. Further studies should be conducted in the laboratory and in the field to confirm these data, expressly to evaluate reproducibility in resource-limited settings, or using whole blood in clinical settings in areas of endemicity and nonendemicity.