Patterns of haemogregarine load, aggregation and prevalence as a function of host age in the lizard Lacerta vivipara.

Patterns of haemogregarine load, aggregation, and prevalence as a function of host age in the lizard Lacerta vivipara were investigated. These parameters may provide evidence for the potential effect of parasites on host survival. The predictions of theoretical models concerning the shape of parasite load, parasite aggregation, and parasite prevalence across host age were used to test if parasites are a significant source of host mortality. Both age-intensity and age-aggregation curves were found to be peaked, whereas the age-prevalence curve increased with host age, reaching high levels (> 80% of infected hosts). These findings of humped age-aggregation and age-intensity curves are in good agreement with the predictions of the Anderson and Gordon (1982) model and suggest that haemogregarines may influence age-dependent host mortality in this population of L. vivipara.