Background: Human enterobiasis is usually mild. Occasionally, however, an "ectopic" disease may occur with a more severe course. Two rare cases of eosinophilic ileocolitis due to Enterobius vermicularis infection are reported here.
Case reports: Case n degree 1 was 46 years old, presenting with fever and bloody diarrhoea. Blood eosinophilia was present. Stool microscopy demonstrated red blood cells and leukocytes. A 2 mm long worm with bilateral cervical wings was found in wet-mount preparations of faecal samples. The Scotch tape test was positive for Enterobius vermicularis eggs. Colon biopsy specimens showed massive eosinophilic infiltration and a typical pinworm section overlying the infiltrated mucosa. Case n degree 2 was a 24-year-old, anti-HIV negative homosexual, presenting with watery diarrhoea. Tests for malabsorption were negative. Three mm long adult male E. vermicularis were found on stool microscopy. Biopsy specimens from the colon showed eosinophilic infiltration. In both cases a 200 mg/day course of oral mebendazole eliminated the symptoms within 3 days.
Conclusions: In these two cases the clinical presentation of enterobiasis was atypical. A common finding was the eosinophilic infiltration of bowel mucosa, although it is still uncertain whether the worm per se may induce mast cell degranulation and eosinophil activation. Nevertheless, the possibility of Enterobius vermicularis infection should be considered in the presence of eosinophilic ileocolitis.