The success of infection by parasites during the host-parasite coevolution is related to increasing a parasite’s ability to alter intermediate host behaviour, resulting in higher fitness of parasites. The “increased host abilities’ hypothesis” posits that parasites manipulate the behavior of their intermediate hosts or improves its chances of intermediate host survival in order to enhance their transmission to the next host. Research shows that the transmission of the parasites to their definitive host is facilitated by non-host predator avoidance by the intermediate host, which would otherwise prevent completion of the parasite’s life cycle.