Herpes simplex virus type 1 colitis: an unusual cause of diarrhea.

Herpetic infections of the gastrointestinal tract are a well-recognized entity. Involvement of the colon seems to be very rare. A 78-yr-old woman developed bloody diarrhea and abdominal discomfort 2 months after surgical treatment for adenocarcinoma of the transverse colon. Colonoscopy revealed diffuse hemorrhagic, erosive, aphtoid, and ulcerative lesions. Histology showed nonspecific inflammatory changes. Herpes simplex virus type 1 (HSV-1) was isolated from endoscopic biopsy and stool specimens. The patient responded rapidly to symptomatic treatment with loperamide. This case demonstrates the potential for HSV-1 to induce infectious colitis; failure to obtain microbiologic evaluations and the rapid response to empiric, symptomatic treatment may be responsible for the rarity of diagnosis of this infection. The implications of this diagnosis are probably more relevant in immunosuppressed individuals, and may be important in the elderly population.