Migratory pattern of zoonotic Toxocara cati and T. canis in experimentally infected pigs

Over a billion people are infected with Toxocara canis or T. cati, the roundworms of dogs and cats. Historically, T. canis has been considered the main responsible of human toxocarosis but as serodiagnosis cannot discriminate the two species, this remains unresolved. We assessed the migratory pattern of T. cati and T. canis in a pig model and found them to be equally infective. Overall, they had a similar migration pattern reaching multiple organs and tissues, including mesenteric lymph nodes, liver, lungs and diaphragm. We recovered larvae of both species in the brain, suggesting that T. cati also can cause neurological toxocarosis in humans. Both species induced systemic eosinophilia and histopathological changes in lungs, livers and mesenteric lymph nodes. This study emphasizes the importance of T. cati as a zoonotic agent and the need to develop diagnostic methods that can differentiate between sources of infection in humans.