Risk factors for the expansion of cutaneous leishmaniasis by Leishmania tropica: Possible implications for control programmes

Abstract

Cutaneous leishmaniasis (CL) caused by Leishmania tropica is emerging in new areas, initially as outbreaks and then establishing endemic foci. There is little evidence of the risk factors and effectiveness of existing control measures, what limits our ability to generalize in different epidemiological settings. The disease is described as anthroponotic; however, zoonotic outbreaks have been reported in some countries. Our aim was to identify risk factors in a recently reported endemic focus in Morocco in order to design more effective control programmes. A case–control study was conducted from September 2014 to October 2015 for epidemiological data collection from families with and without CL cases. Sandflies were captured and L. tropica infection determined. The presence of potential animal reservoirs was evaluated. 71 CL cases (44 diagnosed between 2013 and 2015) and 137 healthy people were surveyed. The average age of the new cases was 33.1 ± 22.3 years, and 69.0% were women. Phlebotomus sergenti was the most abundant species with a density of 4.27 sandflies/trap/night and differences between houses with and without CL cases were detected (p-value = 0.014). Overall, 2.7% female P. sergenti and 3.0% dogs were positive for L. tropica. Human, cat, rabbit and bird blood was detected in blood-fed P. sergenti females. 45% people used preventive measures that were not translated into a reduction in the individual risk of acquiring CL. Exposure to P. sergenti was the only risk factor found, and the reduction in its density could be achieved through the improvement of water wells management, organic fertilizers’ disposal and dogs control. The lack of effectiveness of indoor residual spraying and treated nets are attributable to poor compliance and misuse of them. In addition, result optimization of the awareness campaigns on the public is possible by involving patients with CL to explain their own experience.