Relationship between coffee cultivation practices in Colombia and exposure to infection with Leishmania

The inhabitants of coffee-growing municipalities consistently report the highest annual rates of cutaneous leishmaniasis in Colombia. During the last two decades most Colombian coffee growers have changed from the traditional system of cultivation, where the crop is grown under different species of shade trees, to an intensified system where it is grown at high densities in full sunlight. This change may affect transmission of Leishmania spp. to humans in several ways, probably resulting from reduced human-vector contact. The responses of residents of traditional and intensified coffee plantations to the leishmanin skin test were compared to ascertain whether intensification has indeed affected Leishmania transmission. Although prevalence of infection was significantly higher (P< or =0.01) among residents of traditional plantations (26.8%) than among those of intensified ones (13.2%), no significant difference could be demonstrated with respect to incidence of infection at the time of the study. Similar rates of infection were found for men and women, although the incidence of infection was significantly higher among the latter in intensified plantations. Changes to the type of data collected and the data collection process will facilitate the evaluation of the long-term effects of intensification of coffee plantations on Leishmania transmission.