Efetividade do Programa de Vigilância e Controle da leishmaniose visceral sobre as taxas de incidência e prevalência da infecção assintomática por Leishmania (Leishmania) infantum, Belo Horizonte MG

Abstract

This study evaluated by cross-sectional and cohort epidemiological designs the effectiveness of the strategies of the Surveillance and Control Program of Visceral Leishmaniasis (SCP-VL) in the infection with Leishmania infantum in children. The study was conducted in 2012 in three areas of Belo Horizonte, with different intervention times by SCP-VL (Intervention area 2006: IA2006, intervention area: IA2008 and intervention area: IA2010). In the cross-sectional design 891 children were evaluated. Prevalence rates by ELISA-rK39 in the IA2006, IA2008 and IA2010 were respectively 23.7% (95% CI 19.1 to 28.9), 25.6% (95% CI 21.1 to 30.7) and 17 0 (95% CI 13.1 to 21.8). When compared with prevalence rates estimated at 2010 by Morais. (2011), the prevalence rates of asymptomatic infection increased 83.7% in the area with greater intervention time (IA2006), 74.1% in the area with intermediate intervention time (IA2008) and decreased 5% in the control area, with shorter intervention time (IA2010). In the cohort, 478 children with L. infantum negative serological tests in 2010 (Morais, 2011) were followed. The crude incidence rates were 14.4% in the IA2006, 21.1% and 11.6% IA2008 in the control area, IA2010. The person-time incidence rates were respectively 6.2; 10 and 5.6 / 100 people in 24 months of follow-up in IA2006, IA2008 and IA2010. The analyzes were developed using multilevel logistic regression (odds ratio) for the cross-sectional design and Poisson regression (IRR - incidence ratio) for the cohort design. The infection odds increased in IA2008 (OR = 1.84, 95% CI 1.06 to 3.23) and a higher infection incidence ratio (IRR = 1.76, 95% ; CI 1.05 to 2 95) was found compared to the control area, IA2010. In IA2006 there were no statistical differences between the infection odds (OR = 1.68; 95% ; CI = 0,94- 2,98) and incidence ratio of infection (IRR = 1.18, 95% ; CI 0.65 to 2 14) when compared to IA2010. The results showed that the intervention times and PVC-LV strategies were non effective in reducing asymptomatic infection rates in the studied areas. Even observing slight reduction at infection rates in the control area, IA2010, the circulation and transmission of the parasite were maintained at high levels in all the study areas. It was observed that nobody developed clinical signs or symptoms, which suggests that asymptomatic infection is a good marker for the parasite circulation but is not associated with human desease. The asymptomatic infection by L. infantum was associated with child's age, family socioeconomic status, education of household and presence of trees in the neighborhood. The infection occurrence in at least one child at home was associated with the family socioeconomic status and the presence of trees in the neighborhood .