Morbidity of Chagas heart disease in the microregion of Rio Negro, Amazonian Brazil: a case-control study

A case-control study on the morbidity of Chagas heart disease was carried out in the municipality of Barcelos in the microregion of the Rio Negro, state of Amazonas. One hundred and six individuals, who were serologically positive for Trypanosoma cruzi infection, as confirmed by at least two techniques with different principles, were matched according to age and sex with an equal number of seronegative individuals. The cases and controls were evaluated using an epidemiological questionnaire and clinical, electrocardiograph and echocardiograph examinations. In the seroepidemiological evaluation, 62% of the interviewees recognised triatomines and most of them confirmed that they had seen these insects in the piassava plantations of the riverside communities of the Negro River tributaries. Of the seropositive patients, 25.8% affirmed that they had been stung by the triatomines and 11.7% denied having been stung. The principal clinical manifestations of the seropositive individuals were palpitations, chest pain and dyspnoea upon effort. Cardiac auscultation revealed extrasystoles, bradycardia and systolic murmurs. The electrocardiographic alterations were ventricular extrasystoles, left and right bundle branch block, atrioventricular block and primary T wave alterations. The echocardiogram was altered in 22.6% of the seropositive individuals and in 8.5% of the seronegative individuals.

Morbidade da doença de Chagas em pacientes autóctones da microrregião do Rio Negro, Estado do Amazonas / Morbidity of Chagas disease among autochthonous patients from the Rio Negro microregion, State of Amazonas

INTRODUÇÃO: Foi realizado um estudo soroepidemiológico e clínico em 152 indivíduos residentes no município de Barcelos, Estado do Amazonas. Avaliou-se a soroprevalência da infecção chagásica e a morbidade da doença de Chagas. MÉTODOS: Os testes sorológicos foram a imunofluorescência indireta, ELISA convencional e recombinante e o Tesa-blot. Foram considerados soropositivos 38 pacientes, duvidosos 31 e soronegativos negativos 83. Os 38 casos soropositivos foram pareados com 38 controles soronegativos da mesma idade, sexo e submetidos à avaliação epidemiológica, clínica, eletro e ecocardiográfica, sendo que, 29 pares fizeram exame radiológico do esôfago. RESULTADOS: A soropositividade foi 19,9 vezes mais frequente nos trabalhadores do extrativismo em geral e 10,4 vezes mais frequente no extrativismo da piaçaba. Aplicou-se o teste de reconhecimento com o vetor local do gênero Rhodnius e 86,7 por cento dos pacientes soropositivos o reconheceram, enquanto somente 34,2 por cento dos soronegativos o fizeram. O ECG mostrou-se alterado em 36,8 por cento nos soropositivos e em 21,5 por cento nos soronegativos, enquanto o ecocardiograma mostrou alterações em 31,6 por cento nos soropositivos e 18,4 por cento nos soronegativos. Precordialgia e palpitações foram mais frequentes nos soropositivos. O estudo clínico do aparelho digestivo e radiológico do esôfago não mostrou alterações significativas. CONCLUSÕES. A doença de Chagas na região estudada pode ser considerada uma doença ocupacional.

INTRODUCTION: A seroepidemiological and clinical study was conducted on 152 autochthonous individuals living in the district of Barcelos, State of Amazonas, to evaluate the seroprevalence of Chagas infection and morbidity of Chagas disease. METHODS: The serological tests used were indirect immunofluorescence, conventional and recombinant ELISA and immunoblot (Tesa-blot). Thirty-eight patients were considered seropositive; 31 were considered serodoubtful; and 83 were considered seronegative. The 38 seropositive cases were paired with 38 seronegative controls of the same age and sex, and underwent epidemiological and clinical evaluations, electrocardiograms and echocardiograms. Twenty-nine pairs underwent radiological examinations of the esophagus. RESULTS: Seropositivity was 19.9 times more frequent among workers gathering plant materials from the forests and 10.4 times more frequent among piassaba gatherers. Eighty six point seven percent of the seropositive individuals recognized the genus Rhodnius as the local vector, while only 34.2 percent of the seronegative individuals recognized this. The EKG was abnormal in 36.8 percent of the seropositive individuals and in 21.5 percent of the seronegative individuals, while the echocardiogram showed abnormalities in 31.6 percent of the seropositive and 18.4 percent of the seronegative individuals. Precordialgia and palpitation were more frequent among the seropositive individuals. Clinical evaluation on the digestive system and X-ray on the esophagus did not show significant abnormalities. CONCLUSIONS: Chagas disease in the study region can be considered to be an occupational disease.