Modelling the effect of global warming on the prevalence of schistosomiasis

Abstract

One of the potential health consequences of global warming is a (re-)introduction of vector-borne diseases into certain regions which may, or may not have been, previously endemic. In most tropical countries, such diseases are a major cause of illness and death. One of the most important among them is schistosomiasis, which is associated with one of three species of parasite each of which are transmitted by a specific snail (intermediate host). Temperature and precipitation changes would directly affect the behaviour and geographical distribution of the vectors and the development of the parasites. Climate change could also have an indirect effect by influencing environmental factors such as vegetation and the availability of breeding sites. The direct effects of a change in temperature and precipitation on the transmission potential of the snail population and the consequent effects on human health is evaluated by assessing the change in potential schistosomiasis risk areas and the change in world schistosomiasis prevalence. General Circulation Model based scenarios of anthropogenic global climate change are deployed in the assessment of potential changes in areas vulnerable to the transmission of schistosomiasis. The study shows that the transmission potential of this vector-borne disease is, although to a lesser extent than malaria, very sensitive to climate changes on the periphery of the present endemic areas and at higher altitudes within these areas. The health impact will be most pronounced among populations living in the economically less developed temperate regions in which endemicity has previously been low or absent. In more developed areas it is expected that no major problems will occur since effective control measures are economically feasible as transmission potential would increase.