Background: Congenital transmission (CT) of Trypanosoma cruzi in dogs has not been clearly demonstrated, even though dogs are important reservoirs of this agent. Materials and Methods: Seventeen late pregnant dogs seropositive for T. cruzi were selected, and a total of 84 fetuses were obtained. Blood and heart tissues from the fetuses and dams, and placental tissue from dam were collected. All tissues were analyzed by quantitative polymerase chain reaction (qPCR) for T. cruzi DNA (TcDNA) and inflammatory infiltrate and pathology by histological examination. CT was determined when physical, histological, or molecular evidence of T. cruzi was detected in blood or tissues of the fetuses. Results: A general transmission frequency of 59% was found, and 0.20 ± 0.24 of fetuses per litter were infected. Dams that were qPCR positive for TcDNA in cardiac tissue or blood displayed a transmission frequency of 100% and 67%, respectively. The highest parasite burden was noted in dams that were positive for TcDNA in both blood (82E-01 ± 1.54E-01) and cardiac (5.28E+03 ± 8.85E+03) tissues. In fetuses, higher parasitic burden in blood and cardiac tissue was found in those carried by dams that were seropositive and qPCR positive for TcDNA in cardiac tissue and blood. No amastigote nests were recorded in the cardiac tissue of fetuses in the histopathological studies, but typical lesions of T. cruzi infection were identified in all fetuses where CT occurred. Conclusions: CT of T. cruzi occurred at a high frequency in naturally infected pregnant dogs from the endemic areas.

The use of artificial intelligence has shown good performance in the medical imaging area, in particular the deep learning methods based on convolutional neural networks for classification, detection, and/or segmentation tasks. The task addressed in this research work is the segmentation of amastigote nests from histological microphotographs in the study of Trypanosoma cruzi infection (Chagas disease) implementing a U-Net convolutional network architecture. For the nests’ segmentation, a U-Net architecture was trained on histological images of an acute-stage murine experimental model performing a 5-fold cross-validation, while the final tests were carried out with data unseen by the U-Net from three image groups of different experimental models. During the training stage, the obtained results showed an average accuracy of 98.19 ± 0.01, while in the case of the final tests, an average accuracy of 99.9 ± 0.1 was obtained for the control group, as well as 98.8 ± 0.9 and 99.1 ± 0.8 for two infected groups; in all cases, high sensitivity and specificity were observed in the results. We can conclude that the use of a U-Net architecture proves to be a relevant tool in supporting the diagnosis and analysis of histological images for the study of Chagas disease.

Objetivo. Se describe el caso de un perro parasitado con Spirocera lupi en Yucatán, México, y además, se reportan los casos registrados en dos laboratorios durante 18 años de estudios parasitológicos y de necropsias (2000-2017). Materiales y métodos.Para el primer caso, se incluyen hallazgos de necropsia, histológicos y parasitológicos. Para los estudios retrospectivos se realizaron necropsias y estudios coprológicos de Flotación Centrifugada y de McMaster. Resultados. En el paciente del estudio de caso, durante la necropsia se observaron tres nódulos esofágicos que al realizar la incisión de los mismos, se visualizaron nematodos que correspondieron a S. lupi. En el estudio histológico se observó un granuloma eosinofílico que en su interior contenía el nematodo rodeado por un infiltrado inflamatorio moderado que estaba constituido por neutrófilos, eosinófilos, linfocitos, células plasmáticas y macrófagos; delimitado por una cápsula de tejido conectivo fibroso. En el estudio retrospectivo se encontraron prevalencias de 0.18 y 0.48% mediante pruebas coprológicas y estudios de necropsias, respectivamente. Conclusiones. Spirocerca lupi se encuentra presente en perros de Yucatán, México. Por lo tanto, sería importante considerar esta patología para el diagnóstico diferencial de problemas esofágicos y respiratorios en caninos.

OBJECTIVE: We carried out an exploratory study to determine the infection with Trypanosoma cruzi in the gray fox (U. cinereoargenteus) and the southern spotted skunk (S. angustifrons) in Yucatan, Mexico. METHODS: We used samples from various organs (heart, skeletal muscle, kidney, spleen, liver, esophagus, and stomach) corresponding to individuals of gray fox and spotted skunk, captured in the peridomicile of eight rural localities of Yucatan between the period 1990–2008. The presence of T. cruzi DNA in tissue samples was determined by PCR technique and histopathology study. RESULTS: All the individuals studied had at least one tissue sample with T. cruzi DNA. The esophagus (9/13), heart (7/13), and skeletal muscle (6/13) were the organs with the highest frequency of T. cruzi DNA. No nests of amastigotes were found, however, microscopic observation revealed lesions characteristic of T. cruzi infection, such as inflammatory infiltrate by lymphocytes and histiocytes with or without necrosis of cardiomyocytes cells, and proliferation of fibrocytes, fibroblasts and collagen fibers (fibrosis). CONCLUSIONS: Our results confirm that these two wild carnivores are natural hosts for T. cruzi in Yucatan, Mexico. The synanthropic behavior of these two mammals in Yucatan makes it necessary to focus future studies on their role within the rural peridomiciliary transmission cycle of T. cruzi in the Yucatan Peninsula.