Chagas disease in an area of recent occupation in Cochabamba, Bolivia

RESUMO

A descriptive, entomological and seroepidemiological study on Chagas disease was conducted in a place of recent occupation on the outskirts of Cochabamba, Bolivia Avaroa/Primer de Mayo (population 3.000), where the socio-economic level is low no control measures have been made available. Methods - The immunofluorescent antibody test (IFAT) was used for IgG and IgM anti-Trypanosoma cruzi antibodies in filter paper bloodspot eluates from 128 subject age, gender, birthplace, occupation, duration of residence and building materials used in their houses were recorded. Vectors were captured both in domestic and peridomestic environments. Results - Seropositive, 12,5 per cent (16/128) females, 15.1 per cent (11/73); males, 9.1 per cent (5/55). Average time of residence 6.1 years for the whole population sample and 7.4 years for the seropositive subjects. Most houses had abobe walls (76.7 per cent, n = 30), galvanized iron rooves (86.7 per cent) and earthen floors (53.4 per cent) 80 per cent of the walls had crevices. One hundred forty seven specimens of Triatoma infestans were captured, of which 104 (70.7 per cent) were domestic, and 1 peridomestic Triatoma sordida. Precipitin host identification birds, 67.5 per cent; humans, 27.8 per cent; rodents, 11.9 per cent; dogs, 8.7 per cent; cats, 1.6 per cent. House infestation and density indices were 53.3 and 493.0 respectively. We found 21 (14.3 per cent) specimens of T. infestans infected with trypanosomes, 18 (85.7 per cent) of which domestic environments. Discussion - The elements for the vector transmission of Chagas disease are present in Avaroa/Primer de Mayo and the ancient custom of keeping guinea pigs indoors adds to the risk of human infection. In neighboring Cochabamba, due to sub-standard quality control, contaminated blood transfusions are not infrequent, which further aggravates the spread of Chagas disease. Prompt action to check the transmission of this infection, involving additionally the congenital and transfusional modes of acquisition, is required.