RESUMEN
In this study, we performed a phylogenetic analysis of 35 species of the tribe Triatomini by means of available 16S ribosomal DNA and cytochrome b (Cyt b) gene sequence data, adding taxa of the spinolai complex, to clarify phylogenetic relationships of this complex and related triatomines. The phylogenetic analysis suggests a monophyletic clustering of the spinolai complex related to the South American species of triatomines.
Asunto(s)
ADN Mitocondrial/genética , Triatominae/clasificación , Animales , Argentina , Secuencia de Bases , Análisis por Conglomerados , Citocromos b/genética , ADN Mitocondrial/química , ADN Ribosómico/química , ADN Ribosómico/genética , Proteínas de Insectos/genética , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética , Alineación de Secuencia , Análisis de Secuencia de ADN , Triatominae/genéticaRESUMEN
We report results of Trypanosoma cruzi infection and parasite genotypes in the wild Octodon degus and synantropic reservoir Rattus rattus from an endemic area with sylvatic Triatoma infestans as the only detected vector. The infection status was determined by hemi-nested PCR directed to minicircles DNA and genotyping by hybridization tests with a panel of five specific probes, including two probes for TcI subgroups (clones 19 and 20). O. degus was found infected with 13.3% and mainly with sublineage TcIId, and less with TcIIb and TcI. Meantime the synantropic R. rattus was found infected with 27.7% and mainly with TcI and much less with TcIId, TcIIb and TcIIe. The results are discussed to explain the distribution of T. cruzi genotypes between these two reservoirs and the importance of sylvatic foci of T. infestans allowing the permanence of the wild and peridomestic cycle of Chagas disease.
Asunto(s)
ADN Protozoario/genética , Octodon/parasitología , Ratas/parasitología , Triatoma/parasitología , Trypanosoma cruzi/clasificación , Trypanosoma cruzi/genética , Animales , Chile , Reservorios de Enfermedades/parasitología , Vectores de Enfermedades , Genotipo , Hibridación de Ácido Nucleico/métodos , Reacción en Cadena de la Polimerasa/métodos , Trypanosoma cruzi/aislamiento & purificaciónRESUMEN
Trypanosoma cruzi, the agent of Chagas disease is associated with a very high clinical and epidemiological pleomorphism. This might be better understood through studies on the evolutionary history of the parasite. We explored here the value of antigen genes for the understanding of the evolution within T. cruzi. We selected 11 genes and 12 loci associated with different functions and considered to be involved in host-parasite interaction (cell adhesion, infection, molecular mimicry). The polymorphism of the respective genes in a sample representative of the diversity of T. cruzi was screened by PCR-RFLP and evolutionary relationships were inferred by phenetic analysis. Our results support the classification of T. cruzi in 2 major lineages and 6 discrete typing units (DTUs). The topology of the PCR-RFLP tree was the one that better fitted with the epidemiological features of the different DTUs: (i) lineage I, being encountered in sylvatic as well as domestic transmission cycles, (ii) IIa/c being associated with a sylvatic transmission cycle and (iii) IIb/d/e being associated with a domestic transmission cycle. Our study also supported the hypothesis that the evolutionary history of T. cruzi has been shaped by a series of hybridization events in the framework of a predominant clonal evolution pattern.
Asunto(s)
Antígenos de Protozoos/genética , Trypanosoma cruzi/genética , Animales , Genes Protozoarios/genética , Filogenia , Reacción en Cadena de la Polimerasa , Polimorfismo Genético/genética , Polimorfismo de Longitud del Fragmento de Restricción/genéticaRESUMEN
Eleven years after they had been given itraconazole or allopurinol for the treatment of chronic American trypanosomiasis, 109 adult patients were checked for electrocardiographic abnormalities and evidence of Trypanosoma cruzi infection. The parasitological investigations included xenodiagnosis, in which the faeces of Triatoma infestans that had fed on the patients were checked under the microscope for flagellates. In addition, a PCR-based assay and a hybridization assay were used to test blood samples from the patients, and faeces from the Tri. infestans that had fed on the patients, for Try. cruzi DNA. For the data analysis, the patients were divided into four groups known as normal/normal, abnormal/normal, normal/abnormal and abnormal/abnormal, according to whether the patients had been found to have normal or abnormal electrocardiograms (ECG) shortly before the first treatment and to have normal or abnormal ECG when checked at the 11-year follow-up. The 51 normal/normal and 24 normal/abnormal patients were assumed to have been in the 'indeterminate' phase of the disease when they were treated, whereas the 16 abnormal/normal and 18 abnormal/abnormal patients all had evidence of chagasic cardiopathy at that time. When checked 11 years post-treatment, 40 (78.4%), 17 (70.8%), 14 (87.5%) and 17 (94.4%) of these patients, respectively, were each found positive for Try. cruzi in at least one of the parasitological tests. The hybridization assay, whether applied to human blood or bug faeces, appeared a significantly more sensitive test than the PCR-based assays or microscopically assessed xenodiagnosis (P<0.05). Only the 21 patients who appeared to be negative for Try. cruzi could be considered parasitologically cured (although all still appeared to have anti-Try. cruzi antibodies in their blood). Only 13 of these parasitologically cured patients (seven of those treated with itraconazole and six of those given allopurinol) had normal ECG at the 11-year follow-up. In Chile at least, itraconazole, which caused fewer adverse effects than the allopurinol while being no less effective at preventing cardiopathy, appears to be the drug of choice to treat chronic American trypanosomiasis in adults.
Asunto(s)
Alopurinol/uso terapéutico , Enfermedad de Chagas/tratamiento farmacológico , Itraconazol/uso terapéutico , Adulto , Alopurinol/efectos adversos , Animales , Arritmias Cardíacas/inducido químicamente , Enfermedad de Chagas/diagnóstico , Enfermedad de Chagas/parasitología , Enfermedad Crónica , ADN Protozoario/análisis , Método Doble Ciego , Electrocardiografía/efectos de los fármacos , Femenino , Estudios de Seguimiento , Humanos , Itraconazol/efectos adversos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa/métodos , Trypanosoma cruzi/aislamiento & purificación , Xenodiagnóstico/métodosRESUMEN
PCR and FC-ALTA were used to monitor parasite clearance in 54 chronic chagasic patients who had completed therapy with allopurinol (ALLO, n = 31) or itraconazole (ITRA, n = 23) ten years earlier. All patients maintained positive conventional serology. 25 of them showed positive XD (ALLO, n = 11 and ITRA, n = 14) and 29 negative XD (ALLO, n = 20 and ITRA, n = 9). 43 patients were positive by both techniques (ALLO, n = 23 and ITRA, n = 20). Seven of 54 patients were negative by PCR and positive by FC-ALTA and three of 54 were positive by PCR and negative by FC-ALTA. Only one case with both tests negative should be considered cured. Of 29 patients with negative XD, 14 treated ALLO (70 %) and nine with ITRA (77.8 %) showed positive PCR and FC-ALTA. These results do not show differences of efficacy among the drugs, and reinforce the relevance of using sensitive tools such as PCR and FC-ALTA for the follow-up of patients with chronic Chagas disease.