Serological survey for Chagas disease in the rural areas of Manaus, Coari, and Tefé in the Western Brazilian Amazon

Abstract

Introduction: Deforestation, uncontrolled forest, human population migration from endemic areas, and the large number of reservoirs and wild vectors naturally infected by Trypanosoma cruzi promote the endemicity of Chagas disease in the Amazon region. Methods: We conducted an initial serological survey (ELISA) in a sample of 1,263 persons; 1,095 (86.7%) were natives of the State of Amazonas, 666 (52.7%) were male, and 948 (75.1%) were over 20 years old. Serum samples that were found to be reactive, indeterminate, or inconclusive by indirect immunofluorescence (IFI) or positive with low titer by IFA were tested by Western blot (WB). Serologically confirmed patients (WB) were evaluated in terms of epidemiological, clinical, ECG, and echocardiography characteristics. Results: Fifteen patients had serologically confirmed T. cruzi infection, and 12 of them were autochthonous to the state of Amazonas, for an overall seroprevalence of 1.2% and 0.9% for the state of Amazonas. Five of the 15 cases were males, and the average age was 47 years old; most were farmers with low education. One patient who was not autochthonous, having originated from Alagoas, showed right bundle branch block, bundle branch block, and anterosuperior left ventricular systolic dysfunction with an ejection fraction of 54%. Conclusions: The results of this study ratify the importance of monitoring CD cases in Amazonia, particularly in the state of Amazonas. Keywords: Chagas Disease. Serological Survey. Brazilian Amazon. RESUMOIntrodução: Na Amazônia, o desmatamento desordenado da floresta, as migrações populacionais humanas de áreas endêmicas e o grande número de reservatórios e vetores silvestres naturalmente infectados por Trypanosoma cruzi, favorece a endemicidade da doença de Chagas nessa região. Métodos: Foi realizado um inquérito sorológico inicial por ensaio imunoenzimático (ELISA), em uma amostra de 1.263 pessoas, 1.095 (86,7% ) as quais eram autóctones do Estado do Amazonas, 666 (52,7%) do sexo masculino, 948 (75,1%) com idade superior a 20 anos. As amostras de soro reativas, indeterminadas ou inconclusivas por imunofluorescência indireta (IFI) positivas ou com baixo título na IFI foram submetidas ao Western blot (WB). Os pacientes com sorologia confirmada (WB) foram avaliados do ponto de vista epidemiológico, clínico, eletro e ecocardiográfico. Resultados: Quinze pacientes tiveram sorologia confirmada para infecção por T. cruzi, 12 dos quais autóctones do Estado do Amazonas, com uma prevalência sorológica geral de 1,2% e de 0,9% para o Estado do Amazonas. Entre os 15 casos com sorologia positiva, cinco eram do sexo masculino, média de idade de 47 anos, baixa escolaridade e a maioria agricultores. Um paciente não autoctone, procedente de Alagoas, apresentou bloqueio de ramo direito, bloqueio divisional ântero-superior e disfunção sistólica ventricular esquerda com fração de ejeção de 54%. Conclusões:O resultado deste estudo reforça a importância do monitoramento de casos da doença de Chagas na Amazônia, em especial no Amazonas. Pa...

Chagas disease in the State of Amazonas: history, epidemiological evolution, risks of endemicity and future perspectives

“…In the last few years, the identifi cation of an increasing number of CD acute (5) (14) (16) and chronic cases (5) (9) (17) reiterated that the disease was endemic in the entire Amazon region and that it exhibited particular sub-regional characteristics. In this region, a transmission cycle occurs with a wide array of vectors and wild reservoirs carrying the etiologic agent (6) (18) (19) (20) .…”

“…However, the fi rst report of acute CD occurred in 1980 in São Paulo de Olivença (24) while the fi rst report of an acute case in the state capital, Manaus, occurred in 1994 in the city's urban area (25) . Since then, there have been increasingly frequent records of acute and chronic cases, mainly in the countryside (17) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) . The fi rst xenodiagnosis performed in a chronic patient from the upper Rio Solimões region was made in 1999, from a colony of Triatoma maculata found inside the houses and chicken coops of the Macuxi Indians in the municipality of Normandia, State of Roraima (37) .…”

“…The loss of their natural food sources has attracted triatominae to human houses in search of alternatives, resulting in increased contact with humans and increasing frequencies of acute and chronic cases. Human serological investigations aimed at recording indeterminate cases have been carried out in the outskirts of Manaus and in some rural settlements -i.e., in Coari, Tefe and Barcelos, respectively -and have encountered signifi cant rates of infection (17) (38) (39) .…”

Enfermedad de Chagas y su seroprevalencia en tres departamentos de la Amazonia colombiana.

“…Sin embargo, los cambios del patrón epidemiológico del evento en la región amazónica pueden ser explicados por las transformaciones ambientales y sociales que han sucedido, encauzados por los procesos de la globalización en términos de producción y comercio internacional. Aunque existe evidencia de notificación de casos, no existen registros de domiciliación de vectores en la dinámica de transmisión (18).…”

“…En países como Brasil se ha recogido toda la casuística sobre infectados en fase aguda en la región amazónica y se han descrito estudios de seroprevalencia en población general que van desde 2,8% hasta 5% y de 0,9 a 1,2% en algunos estados de la Amazonia brasilera (1,4).…”