Estudio histopatológico de tejido cardiaco de roedores infectados con Trypanosoma cruzi capturados en barrios suburbanos de Mérida, México / Histopathological study in cardiac tissue of rodents infected with Trypanosoma cruzi, captured in suburbs of Mérida, México

Resumen Introducción. Trypanosoma cruzi es el agente causal de la tripanosomiasis americana, enfermedad endémica en México. Los roedores Mus musculus y Rattus rattus son reservorios del parásito, el cual invade las fibras cardiacas y desarrolla nidos parasitarios produciendo diversas lesiones. Los estudios histopatológicos en roedores naturalmente infectados son escasos. Objetivo. Describir los tipos y las frecuencias de las lesiones microscópicas en muestras de tejido cardiaco de M. musculus y R. rattus infectados con T. cruzi capturados en Mérida, México. Materiales y métodos. Los roedores se capturaron en los barrios suburbanos de Mérida. Se extrajo el tejido cardiaco y se procesó por la técnica de inclusión en parafina y tinción con hematoxilina y eosina. Su examen se hizo con un microscópico convencional y se determinaron todas las lesiones y su grado de afección. Resultados. Se trabajaron ocho muestras de tejido de M. musculus y siete de R. rattus. Se encontraron nidos parasitarios en siete del total de las muestras: en 3 de las 8 de M. musculus y en 4 de las 7 de R. rattus. Se observaron infiltrados inflamatorios en todas las muestras. Otras lesiones fueron la degeneración de las fibras cardiacas (8/15), la congestión de los vasos sanguíneos (6/15) y la necrosis (5/15). Discusión. Las lesiones observadas están descritas en los modelos animales experimentales y en los humanos con tripanosomiasis americana. Los infiltrados inflamatorios se han descrito como la lesión más significativa en los humanos y en los reservorios en la etapa crónica de la enfermedad. Conclusión. Las lesiones observadas están asociadas con la infección con T. cruzi, lo cual confirma que los roedores estudiados son reservorios de este parásito.

Abstract Introduction: Trypanosoma cruzi is the causal agent of the American trypanosomiasis, an endemic disease in México. The commensal rodents Mus musculus and Rattus rattus are reservoirs of this parasite, which invades cardiac fibers and develops parasite nests causing various lesions. Histopathological studies in naturally infected rodents are scarce. Objective: To describe the types and frequencies of microscopic lesions in cardiac tissue of M. musculus and R. rattus infected with T. cruzi captured in Mérida, México. Materials and methods: The rodents were captured in suburban environments of Mérida. Cardiac tissue was extracted and processed by the paraffin inclusion technique and hematoxylin and eosin stained. The observation was made with a conventional microscope and all the lesions, as well as their degree, were identified. Results: Eight tissue samples of M. musculus and seven of R. rattus were studied. Parasite nests were found in 7/15, specifically 3/8 in M. musculus and 4/7 in R. rattus. The inflammatory infiltrate was the most frequent lesion. Other lesions were: Degeneration of cardiac fibers (8/15), congestion of blood vessels (6/15), and necrosis (5/15). Discussion: The lesions we observed have been described in experimental animal models and in humans with American trypanosomiasis. The inflammatory infiltrate has been identified as the most significant lesion in humans and reservoirs in the chronic stage of the disease. Conclusion: The lesions we described are associated with T. cruzi infection, which confirms that the rodents studied are reservoirs of this parasite.

Caracterização clínica da cardiomiopatia chagásica crônica em cães / Clinical characterization of chronic chagasic cardiomyopathy in dogs

On the American continent, almost 15 million people are affected by Chagas disease, resulting in important economic and social damages. Dogs are considered to be an excellent experimental model to study Chagas' disease; as a result, in this research, the characterization of cardiovascular abnormalities was performed in dogs experimentally infected with Trypanosoma cruzi (the Colombian strain) that were at chronic stage. Thirteen adult female dogs were evaluated by electrocardiographic, echocardiographic, hematological and biochemical analyses in the chronic phase. For the electrocardiographic studies, respiratory sinus arrhythmia was the predominant rhythm during the entire research period (49.55 percent to 67 percent), with a low prevalence of right bundle branch block (0-13 percent) and first-degree atrioventricular block (0-14 percent). The spectral Doppler echocardio-graphy showed E and A mitral wave reversal (0.71±0.17), confirming the diastolic dysfunction present in all dogs. An increase in the enzymes activities was detected in the serum analysis, indicating myocardial injury by the infection. Six dogs died during the follow-up. In this way, the clinical characterization of experimentally infected dogs, as described here, increases the knowledge and allows for recognition of the behavioural modifications present in Chagas' disease in affected dogs.

No continente Americano, aproximadamente 15 milhões de pessoas são afetadas pela doença de Chagas, ocasionando importantes danos econômicos e sociais. O cão é considerado excelente modelo experimental para o estudo dessa enfermidade; assim sendo, foram caracterizadas, neste ensaio, as anormalidades cardiovasculares de 13 cães experimentalmente infectados com a cepa Colombiana do Trypanosoma cruzi, em fase crônica (1997-2004). Ao eletrocardiograma, a arritmia sinusal respiratória foi o ritmo predominante durante todo período experimental (49,55-67 por cento), com baixas prevalências de bloqueio de ramo direito (0-13 por cento) e de bloqueio atrioventricular de primeiro grau (0-14 por cento). A EcoDopplercardiografia espectral revelou inversão das ondas E e A mitral (0.71±0.17), confirmando a disfunção diastólica presente em todos os cães avaliados. O aumento da atividade enzimática sérica foi detectado, indicando agressão miocárdica pela infecção. Seis cães morreram durante o período experimental. Desta forma, a caracterização clínica dos cães experimentalmente infectados trouxe informações importantes, possibilitando reconhecer o comportamento clínico dessa importante infecção, na espécie canina.

Disfunção ventricular esquerda em hamsters com doença de Chagas tratados com etanercept / Left ventricular dysfunction in hamsters with Chagas disease and treated with etanercept

Objetivo: a doença afeta mais de 10 milhões de pessoas na América Latina. Leva a cardiomiopatia dilatada inflamatória em 30% dos pacientes como conseqüência tardia da infecção pelo protozoário Trypanosoma cruzi, com pior prognóstico que as outras cardiomiopatias dilatadas. estudos prévios mostram aumento dos níveis circulantes do fator de necrose tumoral-alfa (TNF-x) em pacientes com cardiomiopatia chagásica crônica. Assim, o objetivo do presente trabalho foi avaliar efeito do bloqueio do TNF-x com Etanercept na função ventricular esquerda em hamsters sírios cronicamente infectados pelo T. cruzi...

Acute Chagas' cardiopathy in a polar bear (Ursus maritimus) in Guadalajara, Mexico

Relatamos o caso de uma ursa polar (Ursus maritimus) de 24 anos de idade, que contraiu a infecção chagásica no Zoológico de Guadalajara, em Jalisco, no México, e morreu de cardite chagásica aguda 15 dias após o início da sintomatologia. Os achados histopatológicos são descritos, bem como a presença de triatomíneos (Triatoma longipennis Usinger) infectados por Trypanosoma cruzi coletados a 5 metros do local onde o animal vivia, na cidade de Guadalajara.

We report a 24-year-old female polar bear (Ursus maritimus) who contracted Chagas' infection at the Guadalajara Zoo, in Jalisco, México, and died of acute Chagas' carditis 15 days later. The histopathological findings are described, as well as the presence of triatomids (Triatoma longipennis Usinger) infected with Trypanosoma cruzi collected within 5 meters from the place where the animal lived in the city of Guadalajara.

Evaluacion clinica, electrocardiografica y angiografica de los reservorios naturales de la enfermedad de chagas en la Republica de Panama / Clinical, electrocardiographic and angiographic evaluation of natural reservoirs of Chagas' disease in the Republic of Panama

The authors studied two groups of natural animal reservoirs for Trypanosoma cruzi: a wild one, the common rat Rattus rattus and the house dog, Canis canis. Thirty one naturally infected rats were evaluated with a technique developed by the authors which allows the recording of the ECG and the performance of a ventricular angiogram without altering the functional capacity of the animal. Forty four dogs were followed clinically for a period of twenty years to study the development of the cardiac lesion seen in the chronic phase of the disease. The authors demonstrate the epidemiologic importance of the dog as a reservoir and the ease with which the infection can be acquired from rats, which live in the same habitat with human patients. The most common lesions in both groups were ventricular and atrial arrhythmias and second degree AV block; and, in the dogs, also death due to refractory cardiac failure, such as is seen in the human patient. Right bundle branch block and dilatation of the right cardiac chambers was the rule in both groups. The authors discuss the pathogenesis of the ECG in the rat and its anatomical basis. They propose the possibility of establishing and standardizing this techniques in the laboratories that study rats or other species