SEROPREVALENCE OF TRYPANOSOMA-CRUZI INFECTION IN STUDENTS AT THE 7-14AGE RANGE, LONDRINA, PR, BRAZIL, IN 1995

Seropositivity for Chagas disease was evaluated in 834 children aged b etween 7 and 14 from the Municipal Teaching System in the district of Londrina, State of Parana. A seroprevalence rate of 0.1% was found thr ough the use of an indirect immunofluorescent test and an enzyme-linke d immunosorbent assay. This low rate of seroprevalence provides eviden ce that the vectorial transmission of Chagas disease has been eliminat ed in Londrina. The main reason for the elimination of vectorial trans mission of Trypanosoma cruzi infection, as evaluated by serological te sts, may be a remarkable change in the economic structure of the north ern region of Parana in the 1960's. At that time coffee production was almost completely replaced by soy beans, wheat and grazing in the rur al areas. This change deeply affected the rural ecology and caused an exodus of the population from rural to urban areas as well as a decrea se in the total number of the population of that region. The measures introduced for controlling the disease through the Program of Chagas D isease Control established by the Fundacao Nacional de Saude of the Br azilian Ministry of Health, certainly, had a positive impact on the re duction of American trypanosomiasis prevalence in the area under study . However, it does not seem that this was the most relevant factor res ponsible for the elimination of vectorial transmission of Chagas disea se in Londrina.