Does Virulence Offer Benefit to the Parasite? Does Virulence Offer Benefit to the Parasite?

Abstract Parasites and hosts remain locked in a continuous struggle for survival. The co-evolutionary interactions between the hosts and parasites influence both the host and parasite. Parasite pathogenesis and host defense act in a concert to shape the evolution of virulence. There are various theories on the evolution of virulence in parasite. Host mortality, host resistance, host recovery, mutation, co infection, super infection, host heterogeneity, and mode of transmission have been described for explaining the virulence in parasite. The evolution of parasite virulence focuses on the tradeoff between costs and benefits of the parasite from the host exploitation and appears to be satisfactory. The interaction between the hosts and parasites is multidimensional, dynamic and exceedingly complex. A number of factors perhaps act to shape the level of parasite virulence. Generally, virulence is not beneficial to most of the parasites. Virulence attains a maximum level due to the mutation which is induced by the changing environment. A thorough understanding of pathogenesis including a complete inventory of spatial and temporal expression of genes by both hosts and parasites, from the time of exposure to the final resolution of infection, would contribute a lot in our understanding of evolution of parasite's virulence