The burden of the Leishmania chagasi/infantum infection in a closed rural focus of visceral leishmaniasis in Lara state, west-central Venezuela.

A prospective study was conducted in El Brazilar, Curarigua, Lara State, Venezuela, a small rural focus of visceral leishmaniasis (VL) to investigate the burden and the evolution of Leishmania infection in the human and canine population. The incidence of the disease from February 1998 to February 2002 was recorded and two cross-sectional surveys using the leishmanin skin test (LST) and immunofluorescent antibody test (IFAT) were carried out. The dipstick test with recombinant r-K39 antigen was also applied in 2002. The incidence of the disease per year among the population (n=118) during the period of study was 0.004. The rate of new infections per year was 0.07 [95% confidence interval (95% CI): 0.15-1.09]. The overall prevalence of infection measured by LST was not significantly higher in 2002 (43.2%) than in 1998 (28.3%), but it was with IFAT [16.3%vs. 4.6%; odds ratio (OR): 4.01; 95% CI: 1.03-22.78; P=0.022] which would indicate an increasing transmission. The dipstick test only detected infection in children up to 10 years (19.4%). Prevalence in dogs was not significantly different in 2002 (57%) vs. 1998 (33%). The parasite was isolated from dogs and identified by a polymerase chain reaction based on telomeric sequences as Leishmania chagasi/infantum.