Covert toxocariasis--a cause of recurrent abdominal pain in childhood.

Toxocariasis, usually caused by Toxocara canis, is a zoonosis acquired by ingestion of worms which inhabit the gut of young canines. Domestic pets, such as dogs, become infected from soil in public parks and playgrounds which are often heavily contaminated. Although toxocariasis is often regarded as having two principal, though uncommon, manifestations--visceral larva migrans (VLM) and ocular toxocariasis (OT)--recent studies have suggested otherwise. A third, more common, condition, termed 'covert toxocariasis', describes patients in whom positive toxocara serology is associated with a number of systemic and localised symptoms and signs (notably abdominal pain) but not VLM or OT. A quarter of patients with covert toxocariasis have no eosinophilia and, although symptoms regress after treatment, they may persist for months or years. We report a 13-year-old girl with recurrent abdominal pain who, despite positive toxocara serology, was extensively investigated for other abdominal pathology.