Why some hosts have high parasite burdens and the implications for the design of sustainable control strategies
Nematodes are one of the great neglected diseases: they cause disease and death in wildlife, livestock and humans in poor areas of the world. Most individuals harbour few parasites, but a small proportion of most animal populations carry disproportionately high numbers of parasites. The different burdens reflect variation in exposure (larval intake) and variation in the protective immune response mounted by the host. Thus, hosts with high parasite burdens may be unlucky, predisposed, or both.
Control methods targeted at the heavily infected can be especially effective in reducing clinical disease and in reducing transmission to other members of the population in this and future generations.
Some controls improve the host response (eg selective breeding or nutritional supplementation), whilst others directly reduce average exposure (eg grazing control). Determining the balance between variation in exposure and variation in host response is therefore critical to the selection of control strategies.
Using novel data, new statistical techniques and new understanding of the host response we will build a model that allows the roles of exposure and host response to be distinguished and the best control combinations to be predicted.