Reporte de resultados negativos a Trichinella spp. por digestión artificial en cerdos domésticos del valle inferior del río Negro, Patagonia Argentina / Report of negative results to Trichinella spp. by artificial digestion in domestic pigs of the lower valley of the Negro River, Argentine Patagonia

Resumen Actualmente, el género Trichinella está constituido por 10 especies y 3 genotipos. La transmisión ocurre únicamente por ingestión de tejido muscular infectado. Entre los potenciales hospedadores se conforma un ciclo doméstico y un ciclo silvestre con posible retroalimentación constante entre ambos. Desde el año 2017 el funcionamiento del Matadero Social de San Javier, en el valle inferior del río Negro, permite a productores acceder a una faena segura que además brinde garantías al consumidor. El objetivo del presente trabajo fue evaluar la presencia de larvas L1 de Trichinella spp. en porcinos domésticos procedentes de criaderos de pequeña y mediana escala. Se analizaron por el método de digestión artificial 10 gramos de diafragma de cada porcino doméstico, conformando pooles de hasta 10 animales. En total 942 porcinos domésticos resultaron negativos a la presencia de larvas L1 de Trichinella spp. No obstante debe tenerse presente que sistemas de producción con las características de los que provienen los animales analizados, estarían potencialmente expuestos a la retroalimentación de Trichinella spp. desde la fauna silvestre. En este marco, resulta necesario garantizar el control veterinario en la faena de porcinos y presas de caza y sostener acciones de vigilancia, actualización y promoción en relación a la prevención de la triquinelosis.

Abstract Currently the Trichinella genus consists of 10 species and 3 genotypes. Transmission occurs only through ingestion of infected muscle tissue. Between the potential hosts there is a domestic cycle and a wild cycle with possible constant feedback between both. Since 2017, the operation of the San Javier Social Slaughterhouse, in the lower valley of the Río Negro, allows producers to access a safe operation that also provides guarantees to the consumer. The aim of the present study was to evaluate the presence of L1 larvae larvae of Trichinella spp. in domestic pigs from small and medium-scale farms. 10 grams of diaphragm from each domestic pig were analyzed by the artificial digestion method, forming pools of up to 10 animals. In total 942 domestic pigs were negative for the presence of L1 larvae of Trichinella spp. However, it should be borne in mind that production systems with the characteristics from which the analyzed animals come, would potentially be exposed to the feedback of Trichinella spp. from wildlife. Then, it is necessary to guarantee veterinary control in the slaughter of pigs and game prey and to support surveillance, updating and promotion actions in relation to the prevention of trichinellosis.

Ecology of Trypanosoma cruzi I genotypes across Rhodnius prolixus captured in Attalea butyracea palms.

Trypanosoma cruzi, the agent of Chagas disease exhibits significant genetic diversity. This parasite is divided into six discrete typing units (DTUs) where T. cruzi I (TcI) is the most widespread in the Americas. TcI genotypes have been associated to domestic and sylvatic cycles of transmission (TcIDom and sylvatic TcI). Due to the importance of the enzootic transmission, we determined the frequency of TcI genotypes present in Rhodnius prolixus captured in different regions of the palm A. butyracea to understand the ecology of the disease and the importance of A. butyracea palms as ecotopes of R. prolixus. Forty A. butyracea palms were sampled (base crown, mid-point and crown) capturing 105 individuals identified as R. prolixus by morphological and molecular barcoding. We conducted molecular detection and typing of T. cruzi across 59 individuals. The results showed that all the insects were infected with TcI; 28.57% were sylvatic TcI, 12.38% TcIDom and 15,24% mixed infections (TcIDom/sylvatic TcI). Statistical analysis showed a similar behavior between TcIDom and mixed infections in the mid-point and at the crown of the palm, being more frequent in the crown, while sylvatic TcI does not seem to have a specific association with any of the sampled areas. These findings are consistent with other studies showing high mobility of the insect vector between different ecotopes, increasing the need to develop improvements in the programs of disease control.

Retrospective distribution of Trypanosoma cruzi I genotypes in Colombia

Trypanosoma cruzi is the aetiological agent of Chagas disease, which affects approximately eight million people in the Americas. This parasite exhibits genetic variability, with at least six discrete typing units broadly distributed in the American continent. T. cruzi I (TcI) shows remarkable genetic diversity; a genotype linked to human infections and a domestic cycle of transmission have recently been identified, hence, this strain was named TcIDom. The aim of this work was to describe the spatiotemporal distribution of TcI subpopulations across humans, insect vectors and mammalian reservoirs in Colombia by means of molecular typing targeting the spliced leader intergenic region of mini-exon gene. We analysed 101 TcI isolates and observed a distribution of sylvatic TcI in 70% and TcIDom in 30%. In humans, the ratio was sylvatic TcI in 60% and TcIDom in 40%. In mammal reservoirs, the distribution corresponded to sylvatic TcI in 96% and TcIDom in 4%. Among insect vectors, sylvatic TcI was observed in 48% and TcIDom in 52%. In conclusion, the circulation of TcIDom is emerging in Colombia and this genotype is still adapting to the domestic cycle of transmission. The epidemiological and clinical implications of these findings are discussed herein.

Trypanosoma cruzi diversity in the Gran Chaco: mixed infections and differential host distribution of TcV and TcVI.

The transmission cycles of Trypanosoma cruzi in the Gran Chaco are complex networks involving domestic and wild components, whose interrelationships are not well understood. Knowing the circuit of transmission of the different Discrete Typing Units (DTUs) of T. cruzi in the complex environment of the Chaco region is relevant to understanding how the different components (reservoirs, vectors, ecotopes) interact. In the present study we identified the DTUs infecting humans and dogs in two rural areas of the Gran Chaco in Argentina, using molecular methods which avoid parasite culture. Blood samples of humans and dogs were typified by PCR-DNA blotting and hybridization assays with five specific DNA probes (TcI, TcII, TcIII, TcV and TcVI). PCR analyses were performed on seropositive human and dog samples and showed the presence of T. cruzi DNA in 41.7% (98/235) and 53% (35/66) samples, respectively. The identification of infective DTUs was determined in 83.6% (82/98) and 91.4% (32/35) in human and dog samples, respectively. Single infections (36.7% - 36/98) and a previously not detected high proportion of mixed infections (47.9% - 47/98) were found. In a 15.3% (15/98) of samples the infecting DTU was not identified. Among the single infections TcV was the most prevalent DTU (30.6% - 30/98) in human samples; while TcVI (42.8% - 15/35) showed the highest prevalence in dog samples. TcV/TcVI was the most prevalent mixed infection in humans (32.6% - 32/98); and TcI/TcVI (14.3% - 5/35) in dogs. Significant associations between TcV with humans and TcVI with dogs were detected. For the first time, the presence of TcIII was detected in humans from this region. The occurrence of one human infected whit TcIII (a principally wild DTU) could be suggested the emergence of this, in domestic cycles in the Gran Chaco.

Trypanosoma cruzi, the Causal Agent of Chagas Disease: Boundaries between Wild and Domestic Cycles in Venezuela.

Trypanosoma cruzi the etiological agent of American Trypanosomiasis or Chagas disease (ChD) is transmitted by triatomines vectors between mammals including man. T. cruzi has existed for circa 150 Ma in the Americas and nearly 10 million people are currently infected. The overlap between wild and domestic ecotopes where T. cruzi circulates is increasing. Host-parasite interactions have been determined by infection patterns in these cycles, all under natural or laboratorial conditions. This mini-review describes specific parasite niches, such as plant communities or biological corridors between domestic and wild landscapes, in order to help identify risk factors for ChD and define the boundaries between wild and domestic transmission cycles, with an emphasis on research undertaken in Venezuela.