Variation in infection levels in natural populations due to differences in host susceptibility

Variation in host susceptibility is exemplified from studies where infections of two ectoparasites on Atlantic cod were monitored, the digenean Cryptocotyle lingua (Creplin) and the crustacean Lernaeocera branchialis (L.). The observed differences in infection levels of the two parasites seems to support the idea that sterile immunity against macroparasites may be a suboptimal strategy.