Miocardite no macaco Cebus após inoculações repetidas com Schizotrypanum cruzi

Abstract

<abstract language="eng">Transmission of Chagas disease is realized through contamination of ocular conjunctiva, mucosa or skin with infected dejections eliminated by the insect vectors of Schizotrypanum cruzi (Triatoma infestans, Panstrongylus megistus and Rhodnius prolixus). The triatomid bugs live in holes and craks in the walls, in beds, behind trunks, etc. Found in primitive mud huts covered with thatched roofs, and so the human dwellers have many chances to contract the disease, reinfections being reasonably more to expect than a single inoculation. Experimental work reproducing those natural conditions is welcomed as some important features in the pathologic picture of the disease such as the extensive myocardial fibrosis seen in chronic cases are still incompletely known. Microscopic changes were studied in the heart muscle of seven Cebus monkeys infected by S. cruzi. This animal survives the acute stage of the disease and so is particularly suited to experiments of long duration in which several inoculations of S. cruzi are performed. Three different strains of S. cruzi isolated from acute cases of Chagas' disease were employed. One monkey was injected in the skin with infected blood and necropsied after 252 days. Two monkeys were three times, and one, eight times infected in skin, one of them with contaminated blood, and two with contaminated blood and dejections from infected bugs. The necropsies were performed after 35, 95 and 149 days. One monkey was three times inoculated through the intact ocular conjunctiva (one time with infected blood, two times with dejections from infected bugs), and one time through the wounded buccal mucosa, and necropsied after 134 days. Another monkey was six times inoculated, four times through the intact ocular conjunctiva (one time with contaminated blood, three times with dejections from infected bugs) and two times injected in the skin with infected blood, and necropsied after 157 days. Finally, another monkey was nine times inoculated, four times through the intact ocular conjunctiva (one time with infected blood, and three times with dejections from infected bugs), and five times injected in the skin (four times with contaminated blood, and one time with dejections from infected bugs), and necropsied after 233 days. The microscopic picture was uniform presenting, however, considerable individual variations, and was represented by diffuse interstitial myocarditis, frequently more (marked in the right ventricle base of the heart), accompanied by lymphatic stasis. The infiltration consists of macrophages, plasma cells and lymphocytes, the cellular reaction having sometimes a perivascular distribution, involving the auriculo-ventricular system of conduction, endocardium, epicardium and cardiac sympathetic gangliae. The loss of cardiac muscle fibers was always minimal. Leishmanial forms of S. cruzi in myocardial fibers are scanty and, in two cases, absent. Fatty necrosis in the epicardium was noted in two cases. Obliterative changes of medium-sized branches of coronary a...

Chronic Chagas’ Disease in Rhesus Monkeys (Macaca Mulatta): Evaluation of Parasitemia, Serology, Electrocardiography, Echocardiography, and Radiology

“…[54][55][56][57][58][59][60][61][62][63][64] Electrocardiographic abnormalities, suggesting the presence of acute T. cruzi-elicited myocarditis, have been described in Cebus apella and Saimiri sciureus. 44,[65][66][67][68][69][70] In fact, our animals presented several ECG abnormalities attributed to the presence of the parasite in the cardiac tissue from the fourth week of infection up to the 12th week of the acute phase. 13 Moreover, after 17 years of infection, the ECG abnormalities in monkeys 90, 95, and 103 may have been due to T. cruzielicited myocardial damage, while the alterations observed in monkeys 42 and 64 were transitory and isolated, consequently without diagnostic significance, suggesting that these animals had the indeterminate form of chronic Chagas' disease.…”

Radiological Study of Megacolon in Trypanosoma Cruzi Infected Rats

“…Although literature demonstrates that the amount of the inoculum is directly proportional to the severity of the disease 10 , 13 , 22 , 24 , such results showed that the observed changes in the colon diameter of the animals are not directly related to the inoculum size, but to the time of infection to which animals were submitted.…”

“…However, another important point to be analyzed is the animal’s age; younger ones were the most susceptible to disease 7 , 17 . Only males were used for this experimental model to avoid alterations related to the hormonal cycle of females 22 . According to Soares et al (2012) 2 , studying females mice infected with T. cruzi showed to be more resistant to disease than males.…”

“…Therefore, several experimental models have been used 12 , 14 , 15 . In the first study developed by Oswaldo Cruz, monkeys were used as experimental models, Callithrix Penicillata was inoculated with isolated parasites sent by Carlos Chagas, and trypomastigotes were found in the blood 30 days after inoculation 10 , 13 , 22 , 24 . Cebus monkey was used by Torres&Tavares (1958) 24 for research on myocarditis 17 , and Rhesus monkey by Guimarães and Miranda to study the megaesophagus 10 .…”