Climate and environmental factors affecting the incidence of cutaneous leishmaniasis in Isfahan, Iran

Cutaneous leishmaniasis (CL) is a vector-borne human disease caused by Leishmania, a parasite transmitted by sand flies. CL is endemic in the Isfahan Province, Iran. This study was designed to identify the climate and environmental factors associated with CL incidence in Isfahan Province. Data included incident cases of CL, climate, and environmental factors, which were collected across 23 districts of province from 2007 to 2015. Analyses were performed with generalized linear models (GLMs) to fit a function to the relationships between the response and predictors. We used negative binomial regression due to over-dispersed distribution of CL cases. The effects of all seven climate and environmental factors were found to be significant (all p < 0.01), and the model explained 40% of the deviance of CL incidence. There was a positive relation between mean temperature, relative humidity, and slope of area with disease incidence; however, negative association was demonstrated between maximum wind speed, rainfall, altitude, and vegetation cover with CL incidence. Cutaneous leishmaniasis continues to be a widespread challenge, especially in northwestern parts of Iran. Climate and environmental factors should be considered when selecting the most appropriate strategies for preventing and controlling CL.