|Bottlejaw: symtom of presence of H. contortus.
|Life cycle of H. contortus.
|Sign of Anemia. http://www.sheep101.info/201/parasite.html|
|Aggregated hosts. http://www.premier1supplies.com/sheep/species.php|
The distribution of H. contortus is highly aggregated. Due to internal multiplication, the aggregation of parasites during infective stages, and most importantly, the behavior of the host, the parasite tends to be distributed aggregately. In addition, the relationship demonstrates the coevolution of parasite and host. Although most sheep and goats bear little resistance to H. contortus, the breeds that do bear resistance suggests coevolution. The parasite certainly inflicts virulence upon the host, as the host loses fitness as it succumbs to its parasitic counterparts .