Trypanosoma cruzi genotyping supports a common source of infection in a school-related oral outbreak of acute Chagas disease in Venezuela.

Trypanosoma cruzi I, a discrete typing unit (DTU) found in human infections in Venezuela and other countries of the northern region of South America and in Central America, has been recently classified into five intra-DTU genotypes (Ia, Ib, Ic, Id, Ie) based on sequence polymorphisms found in the spliced leader intergenic region. In this paper we report the genotype identification of T. cruzi human isolates from one outbreak of acute orally acquired Chagas disease that occurred in a non-endemic region of Venezuela and from T. cruzi triatomine and rat isolates captured at a guava juice preparation site which was identified as the presumptive source of infection. The genotyping of all these isolates as TcId supports the view of a common source of infection in this oral Chagas disease outbreak through the ingestion of guava juice. Implications for clinical manifestations and dynamics of transmission cycles are discussed.

Oral transmission of Chagas disease: typing of Trypanosoma cruzi from five outbreaks occurred in Venezuela shows multiclonal and common infections in patients, vectors and reservoirs.

In Venezuela six episodes of oral transmission of Chagas disease (OChD) have been described, being the one reported in 2007 with a total of 103 people infected the largest worldwide. This work shows the use of three molecular markers (mini-exon gene and domains 24Sα and 18S of the ribosomal RNA) to characterize the infecting Trypanosoma cruzi strain of patients, reservoirs and vectors involved in five of the six OChD outbreaks. For this, 28 T. cruzi isolates were characterized by PCR, and the products of these reactions cloned and sequenced to reveal the existence of different TcI SL-IR genotypes. We also describe a new PCR assay able to discriminate between TcIb and TcId parasite populations. In summary, we have identified mostly parasites with the TcId haplotype and multiclonal populations with predominance of haplotype TcId (65.2%). Additionally, populations of haplotypes TcIb, TcIa and mixtures (TcId+TcIb, TcId+TcIa, TcIb+TcIa) are recurrent in samples obtained from children. The analysis of the SL-IR motif showed two clones depicting a different motif that could be an evidence for a possible hybrid haplotype between TcIa and TcIb (haplotype TcIa/Ib). Interestingly, in a single patient haplotype differences between T.cruzi isolates obtained pre and post-treatment were found. In conclusion, our findings show that in order to understand the pathogenic mechanisms involved in the orally acquired Chagas disease there is a need to join efforts to study T. cruzi haplotypes, their tissue tropisms and their susceptibility to chemoteraphy.

Commercial coconut palm as an ecotope of Chagas disease vectors in north-eastern Venezuela.

BACKGROUND & OBJECTIVE: There are few reports of Coccus nucifera (Palmae) infestation by triatomines (Hemiptera, Reduviidae, Triatominae), vectors of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae), the causal agent of American Trypanosomiasis. The aim of this study was to determine if this palm is an appropriate ecotope for Rhodnius prolixus and Triatoma maculata, the main vectors in Venezuela. METHODS: Dry and green leaves, humid debris, interfoliaceus meshes and bracts from C. nucifera from north-eastern Venezuela were examined for the presence of triatomines. Samples of the intestinal content of vectors, macerated in isotonic saline solution and haemolymph were examined microscopically for the presence of Trypanosoma spp. The parasites were isolated and characterized using biological parameters and PCR. Triatomine blood meal sources were determined using ELISA. RESULTS: A total of 14 palms were examined in which viable eggs of both species of vectors were found in 13 palms (92.85%). A total of 242 R. prolixus and 144 T. maculata adults were collected, of which 98% of R. prolixus and 70% of T. maculata individuals were infected by T. cruzi (TcI genotype) and 13% of R. prolixus individuals showed a mixed infection with T. rangeli, the other American trypanosome. ELISA testing for possible triatomine blood-meal sources revealed that these vectors are essentially eurytrophic and zoophilic, although R. prolixus also eventually used human blood as a nourishment source. INTERPRETATION & CONCLUSION: The results obtained suggest that C. nucifera is an appropriate vegetal niche for these triatomine species in Venezuela. The presence of this commercial palm may represent a useful environmental bioindicator of risk for Chagas disease.

Panstrongylus rufotuberculatus (Champion, 1899) naturalmente infectados con Trypanosoma cruzi en el estado Miranda, Venezuela / Panstrongylus rufotuberculatus (Champion, 1899) naturally infected with Trypanosoma cruzi in Miranda state, Venezuela

Dos ejemplares de Panstrongylus rufotuberculatus fueron capturados en una vivienda de El Hatillo, estado Miranda. En ambos se confirma la presencia de Trypanosoma cruzi. Se estudian algunos parámetros biológicos para estimar el comportamiento de uno de los aislados (Pr), encontrándose que tanto el cultivo en medios acelulares como la inoculación en ratones fueron exitosos. Así mismo, 73,3% de los Rhodnius de laboratorio se infectaron y 30,6% de los parásitos presentaron metaciclogénesis, mientras que in vitro se obtuvo 25,5%. La identificación molecular correspondió a T. cruzi. Este hallazgo es importante debido a la posible emergencia de esta especie silvestre que por alteración antrópica de sus hábitats naturales puede estar en proceso de dispersión, penetración y domiciliación de las viviendas, implicando la posibilidad de transmisión del parásito al ser humano y animales domésticos.

Two specimens of Panstrongylus rufotuberculatus were captured in a house in El Hatillo, Estado Miranda. In both specimens the presence of Trypanosoma cruzi was confirmed. We studied some biological parameters for estimating the behavior of the isolates, finding in both that cell-free culture media as inoculation in mice were successful. Also, 73.3% of Rhodnius prolixus fed on infected mice became infected and 30.6% of the parasites developed to metacyclic forms whereas in vitro only 25.5% was obtained. Furthermore, the molecular identification corresponded to T. cruzi. This finding is important due to the possible emergence of wild species by anthropogenic alteration of their natural habitats, and this may become a process of dispersion, penetration and clearance of houses, implying the possibility of transmitting the parasite to humans and pets.

Stridulatory sound emission of Panstrongylus rufotuberculatus Champion, 1899, (Hemiptera: Reduviidae: Triatominae).

This study contains the first report of stridulatory sound observed in Panstrongylus rufotuberculatus Champion, 1899, and also a new record of this species in Venezuela. The conditions in which stridulation occurred are described, as well as the general environmental characteristics of the localities where it was found. This triatomine only performs the sound in conditions of extreme provocation.

Stridulatory sound emission of Panstrongylus rufotuberculatus Champion, 1899, (Hemiptera: Reduviidae: Triatominae)

Este estudo contém o primeiro reporte da estridulação observada em Panstrongylus rufotuberculatus Champion, 1899, e um novo registro desta espécie na Venezuela. Descrevem-se as condições em que ocorre a estridulação, como também as características gerais das localidades onde foi capturado. Este triatomino só emite som em condições de extrema provocação.

Stridulatory sound emission of Panstrongylus rufotuberculatus Champion, 1899, (Hemiptera: Reduviidae: Triatominae)

This study contains the first report of stridulatory sound observed in Panstrongylus rufotuberculatus Champion, 1899, and also a new record of this species in Venezuela. The conditions in which stridulation occurred are described, as well as the general environmental characteristics of the localities where it was found. This triatomine only performs the sound in conditions of extreme provocation.

Este estudo contém o primeiro reporte da estridulação observada em Panstrongylus rufotuberculatus Champion, 1899, e um novo registro desta espécie na Venezuela. Descrevem-se as condições em que ocorre a estridulação, como também as características gerais das localidades onde foi capturado. Este triatomino só emite som em condições de extrema provocação.