Adult Toxocara cati infections in U.S. children: report of four cases.

We report four cases of passage of subadult or adult Toxocara cati worms by young children ages 20 months to seven years. Worms were expelled rectally in two cases and in two cases they were vomited. A single worm was passed in two cases, three worms in one case, and 15 worms in the fourth case. All worms that were available for study were identified as T. cati by morphologic criteria, including the arrow-shaped cervical alae and the digitiform shape of the male tail. None of the four children exhibited clinical signs of ocular or visceral larva migrans, and in two cases where serum samples were available, neither child had a titer to Toxocara. These results further the argument that these children acquired the worms through the ingestion of immature worms passed by infected cats, not through the ingestion of infective eggs. Although the children were generally not ill as a result of these unusual infections, it does serve to reinforce the public health issue that potential serious consequences can occur where children have exposure to an environment that has been contaminated with cat feces, or, more specifically, infective eggs, and could become infected with larval forms of Toxocara.