Enterobius vermicularis infection associated with positive faecal occult blood testing and eosinophilia

Abstract

A 60-year-old asymptomatic man attended following positive faecal occult blood testing in the UK bowel cancer screening programme. He was a regular carer for young grandchildren. Recent blood tests showed an elevated eosinophil count (0·82 × 109 cells per L [range 0·04–0·4]). Colonoscopy showed patchy erythema and erosions with multiple Enterobius vermicularis (threadworm or pinworm) in the caecum (figure, A). Histopathological examination (figure, B) showed surface epithelial erosion, with attenuation, patchy regenerative changes and an E vermicularis parasite (figure, C). Crypt architecture was maintained, but there was an eosinophil-rich inflammatory cell infiltrate within the lamina propria (figure, D).