Transmission dynamics of Taenia solium and potential for pig-to-pig transmission

Taenia solium taeniasis/cysticercosis is one of few potentially eradicable infectious diseases and is the target of control programs in several countries. The larval stage of this zoonotic cestode invades the human brain and is responsible for most cases of adult-onset epilepsy in the world. Our current understanding of the life cycle implicates humans as the only definitive host and tapeworm carrier, and thus the sole source of infective eggs that are responsible for cysticercosis in both human and pigs through oral-faecal transmission. Here we review transmission dynamics of porcine cysticercosis including an alternative pig-to-pig route of transmission, previously not suspected to exist. Second-hand transmission of T. solium eggs could explain the overdispersed pattern of porcine cysticercosis, with few pigs harbouring heavy parasite burdens and many more harbouring small numbers of parasites.