Cutaneuous Leishmaniasis Incidence and Annu-al Climatic Variations: A Statistical Analysis, Case Study of Mashhad, Iran

Background Cutaneous Leishmaniasis (CL) is an important infection with a high incidence rate. The
spatiotemporal dynamics of this disease is mainly determined by three main components of parasite,
reservoir and vector. Climatic factors can significantly affect its incidence through their impact on these components.

The present study aimed to assess the effects of climatic changes on the incidence rate of CL in Mashad, Iran. To this end, first different phases of drought were identified through Standard Precipitation Index (SPI). Then the relationship between the incidence of CL and these phases was analyzed with non-parametric Kruskal-Wallis test and Dunn-Bonferroni test at a significance level of 95%.

The results of the non-parametric Kruskal-Wallis test on the incidence of CL in the three phases of drought showed a significant relationship between them. Dunn-Bonferroni test showed that the incidence of CL was significantly higher during the years with severe drought as compared to years with normal rainfall. The significant increase in the mean incidence of CL during severe drought can be attributed to limited food sources available to the vectors, which are mostly rodents.

Scarcity of food sources during drought makes rodents, as the main vector of the disease, to seek food and be more exposed to sandflies. That is how the incidence of CL increases.