Nematode Larva Migrans

Larva migrans (LM) refers to the prolonged migration and persistence of helminth larvae in the organs and tissues of humans and animals, and also refers to the disease entities resulting from paratenic larval migration. This chapter focuses on zoonotic LM caused by the canine and feline ascarids, raccoon ascarid, gnathostomes, and hookworms of animals. Toxocariasis is a helminthic infection caused by larvae of Toxocara spp. Only two species, T. canis and T. cati, are known to cause disease in humans. Baylisascaris procyonis causes visceral larva migrans, neural larva migrans, and ocular larva migrans of humans. Gnathostomiasis, caused by Gnathostoma, has been clearly linked to certain unsafe food preparation practices and consumption of infected fish and meat carrying the larvae. Cutaneous larva migrans caused by the larvae of skin-penetrating nematodes, most commonly the animal hookworms.