The ecology of cutaneous leishmaniasis in the Negev and the Arava: Role of human activity

An increase in the incidence of cutaneous leishmaniasis (CL) has been reported in southern Israel during the last 20 years. This increase appears to be associated with human activity. Is this increase due to the entry of more people into endemic regions, or does human activity alter the environment, thus, increasing infection probability? The study was conducted at 5 sites: Hazeva, En Yahav, Ne'ot Hakikar, Sede Boqer, and Nizzana. At each site I established twelve 60 × 60 m plots: 6 in disturbed habitat and 6 in natural habitat. In each plot, rodents and sandflies were trapped and environmental variables were measured. To asses the impact of human activity on the zoonotic system, I compared densities of the host (fat sand rat, Psammonys obessus), the vector (Old-World sandfly, Phlebotomus papatasi), and the prevalence of CL. CL prevalence in Psammonys obessus was significantly higher in the disturbed habitats sites, and was positively correlated with vector density but not with host density. Sandfly density was positively correlated with soil moisture, and soil in disturbed habitats was significantly moister than that in natural habitats. These results suggest that human activity improves the breeding conditions of the vector, as well as the food quality of the host.