Will Climate Change Affect Parasite- Host Relationship?
Research examining the causal relationships between climate, climate change and parasite ecology is the focus of increased attention. Understanding how parasites are likely to be affected by climate change requires an examination of the interactions between climate and parasite ecology and transmission. The distribution, prevalence and abundance of a parasite is determined by availability of susceptible hosts, environmental thresholds for development (for either free-living or parasite stages in poikilothermic intermediate hosts and vectors) and resilience, bounded by upper and lower tolerances for survival. Furthermore, life history parameters such as how free living stages are distributed in the environment (as eggs or larvae) and the potential for arrested development can interact with climate and shorter-term weather patterns to influence distribution. Thus, to a great extent, the actual or realized distribution of parasites in time and space is influenced largely by climatic factors. These factors also contribute to the ecological parameters determining parasite survival and hence transmission. Thus, the changes in climatic variables can alter parasite ecology by affecting host and geographic distribution, infection pressure, prevalence and intensity of parasites and can do so directly ( via free-living stages) or indirectly (by affecting hosts). Shifts or expansion in distribution, prevalence and intensity of parasites will be closely linked with that of their hosts and will be dependent on numerous factors driving change. The effects of environmentally detrimental changes in local land use and alterations in global climate disrupt the natural ecosystem and can increase the risk of transmission of parasitic diseases to the human population.