Fig. 3.

Several factors influence the spread of Baylisascaris procyonis, infestation rates are higher in urban and agricultural environments than in semi-natural sites. Thus, a denser population of raccoons in urban areas has a beneficial effect on infestation numbers. However, other factors such as vegetation density as well as available food resources, microclimate, soil characteristics, and land use also influence the rate of B. procyonis infestation and zoonotic potential. An Unembryonated eggs are shed by the raccoon. Eggs undergo 2–4 weeks of development outside the body until the embryonated and infective stage is reached. Embryonated eggs can remain in the environment for several months and remain infectious. B In urban and agricultural areas, new intermediate hosts are frequently infected. These are either eaten by the raccoon or can become infected like the raccoon (e.g., dogs) and then also excrete eggs. C In urban and agricultural areas, there are usually other off-target hosts than in semi-natural areas. Here, for example, cattle or chickens have been confirmed as false hosts. In these hosts, visceral or ocular larva migrans is induced without the larvae being ingested by the raccoon. D Children can become infected with infectious stages and contract Larva migrans through constructed latrines as well as simple defecation in or near play facilities (e.g., sandboxes, climbing houses). E Due to the steady spread of raccoons, new false hosts are increasingly infected with eggs of B. procyonis, such as chicken birds (pheasants), even in semi-natural areas. F The normal life cycle of B. procyonis includes the prey of P. lotor such as various small mammals or birds. In Europe, these species also play the main role in semi-natural habitats. G Raccoons, as the primary host, become infected with B. procyonis by direct ingestion of embryonated eggs through contact with latrines and via excreted feces of infected raccoons. Numerous small mammals or birds serve as paratenic or intermediate hosts, passing larvae directly to the raccoon. The worms grow in the raccoon and can reach high densities in the raccoon's intestine.