Incidence of Vector-borne Disease and Climate Change: A Study in Semi-arid Algeria

Leishmaniases are among the most important emerging and resurging vector-borne diseases, second only to malaria in terms of the number of affected people. Leishmaniases are endemic in 88 countries worldwide and threaten about 350 million people (WHO, 2007). Since the first reported case of zoonotic cutaneous leishmaniasis (ZCL) in Saida, Algeria in 1991, 1,275 cases have been recorded (Makhlouf & Houti, 2010) with the vast majority of study-area cases (99%) reported between the years of 2000 and 2009. An investigation of potential climatic indicators for the apparent shift in disease prevalence was conducted by comparing anomalies in the climate data specific to the local pathogen cycle. It was determined that long term climate trends have resulted in conditions that promote the prevalence of ZCL. Increased precipitation have resulted in greater vegetation and promoted host and vector population growth through a trophic cascade. Increased minimum temperatures have lengthened the annual duration of sandfly activity. Short term variations in maximum temperatures, however show a correlation with disease suppression in the subsequent years. These findings indicate a potential to forecast the risk of ZCL infection through models of the trophic cascade and sandfly population growth.