Toxocariasis is caused by nematodes of the genus Toxocara. Adult worms live in the intestines of dogs and cats, which fecally discharge millions of eggs daily. These eggs become widely distributed (up to 30% of soil samples contain them),175 and humans become infected when they ingest ova-containing soil. Ova hatch in the small intestine, producing larvae that traverse the intestinal wall and migrate to various tissues.

Immune response to migrating larvae produces the disease called visceral larva migrans, which sometimes affects the brain. Most infections are asymptomatic. If symptomatic, headache is the most common CNS complaint, although meningoencephalitis with seizures has been described.176

Interestingly, children with idiopathic epilepsy have the antitoxocaral antibody more often than controls, prompting the hypothesis that toxocariasis may be an etiologic factor in epilepsy.177 This hypothesis remains unsettled.

Adapted from: Goldstein MA and Harden CL. Infectious states. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;83-133.
With permission from Elsevier ( 

Reviewed By: 
Steven C. Schachter, MD
Monday, March 1, 2004