Parasite co-infections generate temporal and spatial variation in host susceptibility and infectiousness

Parasite co-infections modify host susceptibility, parasite intensity and distribution across the host population. Here we examine the hypothesis that susceptibility and infectiousness vary in the same host depending on the past history of infection and the presence of co-infections. We have used time series of a natural population of rabbits and three of their common parasites, two gastrointestinal nematodes and a virus, and explored changes in the pattern of nematodes infection between seasons and warrens. We found that co-infections enhanced sex bias parasitism, time of infection and potentially have large effect on parasite transmission, these patterns were highly seasonal. Co-infected hosts were likely to come from the same warrens. We conclude that co-infections affect seasonal and spatial variations in host susceptibility and generate highly infected hosts that remain infectious for longer time.