Utility of the polymerase chain reaction in detection of Trypanosoma cruzi in Guatemalan Chagas' disease vectors.

Abstract

Abstract. For effective control programs, accurate assessment of Trypanosoma cruzi infection in vectors is essential and has traditionally been performed by microscopic examination. For particular vectors and not others, polymerase chain reaction (PCR) analysis of fecal samples recently has been shown to be an effective means of detection. The sensitivities of the PCR and microscopy for detection of T. cruzi in different anatomic sites were compared in the two major vectors of Guatemala, Triatoma dimidiata and Rhodnius prolixus. Preliminary studies established that T. cruzi can be detected by the PCR in the presence of 90% T. rangeli. One hundred thirty-five vectors were collected, and samples were obtained from the rectum, intestines, and stomach and analyzed by microscopy and the PCR. For Triatoma dimidiata rectal samples, the PCR sensitivity (39.1% T. cruzi positive) and the microscopic sensitivity (24.6% positive) was not significantly different. However, in R. prolixus, the PCR proved significantly more sensitive than microscopy: 57.6% positive by PCR compared with 22.7% by microscopy. Rectal samples showed the highest rates of infection followed by intestine and stomach samples. However, 10

Suitability of a rapid DNA isolation and amplification for detection ofTrypanosoma cruziinTriatoma infestansdry fecal spots collected on filter paper

“…Nevertheless, all negative filter paper samples revealed the 144 bp DNA fragment after addition of T. cruzi DNA thus confirming the inexistence of amplification inhibitor factors what was crucial to rule out the presence of inhibitors, that have already been reported by Breniere et al (1995) who used the same boiling procedure of the present study, and Araújo et al (2002) who used a more complex extraction procedure with phenol-chloroform extractions. Dorn et al (1999;2001) have associated amplification inhibition to the type of biological sample, suggesting that digestive tract samples, especially stomach contents are more prone to inhibit PCR. We decided to increase the number of insects in the second study group (lower parasitemia model) with a proportional reduction of the number of insects in the control group due to the loss of some insects during the first experiment (high parasitemia), and also because all negative triatomines did not generate any amplification during the first part of the study, taken into account that our capacity to breed and maintain triatomines was limited by the laboratory infrastructure.…”

Detection of Trypanosoma cruzi and Trypanosoma rangeli infection in triatomine vectors by amplification of the histone H2A/SIRE and the sno-RNA-C11 genes

“…Among different research groups, different PCR detecting systems have been reported for detecting T. cruzi and T. rangeli in the intestinal content from experimental and naturally infected vectors. In this sense, DORN et al (1999) 9 showed that the TC1/TC2 minicircle targed PCR assay was biased to T. cruzi since T. rangeli must constitute at least 75% of the sample in the presence of T. cruzi for detection by the PCR.…”

“…Due to direct microscopic detection of trypanosomes, the traditional method for assessment of infection in vectors is not able to distinguish T. cruzi from T. rangeli infection, several polymerase chain reaction techniques have been developed 3,4,5,6,9,13,19,28,33,36,40,41 . However, current PCR assays used for mixed infection detection show some disadvantages such as the amplification of bands of similar size both in T. cruzi and T. rangeli 27,28 , the amplification of polymorphic fragments 11,19 , and bias to T. cruzi in the case of mixed T. cruzi and T. rangeli infection 9,33,36 .…”

“…However, current PCR assays used for mixed infection detection show some disadvantages such as the amplification of bands of similar size both in T. cruzi and T. rangeli 27,28 , the amplification of polymorphic fragments 11,19 , and bias to T. cruzi in the case of mixed T. cruzi and T. rangeli infection 9,33,36 . Therefore, it is necessary to develop new techniques as better options to specifically identify each of these parasite species in mixed infections.…”

High infection rates ofTriatoma dimidiataare associated with low levels ofTrypanosoma cruziseroprevalence in Pedro Carbo, Ecuador. Use of atc24 gene-based PCR approach

“…Molecular tools such as the Polymerase Chain Reaction (PCR) allow the analysis of multiple samples with high specificity and sensitivity. Previous reports have shown the applicability of PCR for epidemiological studies of T. cruzi (Brenière et al, 1995 ;Dorn et al, 1999 ;Shikanai et al, 1996). In this study, we compare the microscopic and PCR method, using T. cruzi (tc24) specific primers, for detecting T. cruzi infection in Triatoma dimidiata, one of the principal Ecuadorian vectors of Chagas' disease.…”