Chagas disease in a community in Southeast Brazil: I. A serlogic follow-up study on a vectorcontrolled area

Abstract

The prevalence of Trypanosoma cruzi infection was evaluated in Berilo, Minas Gerais (MG), Brazil, from January to July 1997. A serological survey using the indirect immunofluorescence test (IFT) in dried blood collected on filter-paper was performed in a sample of 2,261 individuals. The overall prevalence rate of T. cruzi infection was 18%, and reached 50% in individuals older than 30 years from rural areas. The percentage of seropositivity was 0.17% among individuals younger than 10 years old, suggesting that vectorial transmission is controlled in the area. A decrease in prevalence rates among people born after 1960 and 1970 was observed and this appears to be correlated with the beginning of control programs. A reduction in T. cruzi infection rates was observed when comparing our results with the rates estimated in a serologic study carried out in Berilo in 1983.

Seroprevalence of Chagas disease in schoolchildren from two municipalities of Jequitinhonha Valley, Minas Gerais, Brazil; six years following the onset of epidemiological surveillance

“…Herein, the screening immunoassay by ELISA using BEFP detected 2.69% of seropositivity (38/1,412). This higher positivity in screeening tests for Chagas disease in BEFP in relation to serology was observed by MACHADO-COELHO 21 and also by MONTOYA et al 23 . Our results of seroprevalence of 0.4% in schoolchildren were similar to those observed by this author in zero to nine year-old children in the same area, six years before.…”

“…However, this prevalence is lower that the one described by AGUILAR 1 who detected 1.6% of seropositive children younger than 10 year-old and it is interesting to note that all seropositive children identified in our investigation were born before the beginning of the epidemiological surveillance for Chagas disease in this region. These data are suggestive of a positive impact of Chagas disease control program adopted by these two municipalities, if considered that our investigation was carried out six years later than that performed by MONTOYA et al 23 .…”

“…This group was selected considering logistic facilities, 100% children school attendance and the possibility of comparing the present seroprevalence of this group of age with the former seroprevalence (0.2%) found by MONTOYA et al 23 in the group aged zero to nine years old, in the same study area.…”

“…However, one of the infected children showed an enlarged Pri, which could be an early and transient ECG Chagasic alteration, frequently found in chagasic children during and after the acute phase of the infection 13,23,26 . Similar findings were previously reported regarding the high prevalence of early ECG abnormalities in T. cruzi infected children 3 .…”

“…However, the control program was continuously executed only between 1970 and 1980. After these effective vector control practices, a serological survey performed in 1997, including 2,261 volunteers, indicated a Chagas disease infection prevalence of 18.0% with rare cases of positivity observed in children under 10 years of age (0.17%), suggesting interruption of the vectorial transmission of the disease and success in vector control actions 23 .…”