CUTANEOUS LEISHMANIASIS IN THE PERUVIAN ANDES, RISK-FACTORS IDENTIFIED FROM A VILLAGE COHORT STUDY

Risk factors for cutaneous leishmaniasis were identified from a compar ative study of transmission rates in 27 villages in the Departments of Lima, Ancash, and Piura in Pent. To evaluate regression analysis as a tool for the incrimination of sand fly vectors in the absence of othe r biologic evidence, univariate and multivariate logistic regression a nalyses were used to identify which of 14 variables (the abundance of nine sand fly species, four social factors, and region) predicted tran smission rates in villages (incidence, active prevalence, or cumulativ e prevalence). In general, suspected or proven vectors (e.g., Lutzomyi a peruensis) had the strongest associations with transmission rate. in dicating that regression is a useful supplementary method of incrimina ting vectors. Regression was then used to quantify the importance of s uspected risk factors. Transmission rate increased with the abundance of Lu. peruensis, Lu. ayacuchensis, Lu. noguchii, and, to a lesser ext ent, Lu. verrucarum and transmission was higher among villagers who sl ept more frequently in temporary shelters in crop areas. There were al so weak effects of the number of dogs/person (negative) and the number of persons/household (positive). Linear regressions failed to detect a threshold sand fly density below which transmission ceases. The mini mal adequate multiple regression model explained 82% of the variance i n village incidence rates. This model was used to predict the effect o n incidence of reducing each of the four suspected vectors in northern and southern Pen. The results indicate that vector control programs i n the south should aim at Lu. peruensis, Lu. verrucarum, and Lu. noguc hii, but focus on Lu. ayacuchensis in the north.