[Cytomegalovirus colitis in an immunocompetent child].

Cytomegalovirus (CMV) colitis is uncommon in young infants. Here we report a case of a 10-week-old breastfed infant admitted to the emergency room for rectal bleeding. He had had stools streaked with red blood for four days, was in good general condition, and was apyretic. Blood count, C-reactive protein, stool bacteriology and virology, abdominal X-ray examination, and abdominal ultrasounds did not reveal any abnormality. Cow's milk protein allergy was suggested despite the negativity of specific immunoglobulins E (IgE) and a diet excluding cow's milk protein was initiated in the mother. In a context of persistent rectal bleeding and good general condition, an endoscopic examination found diffuse hemorrhagic colitis and an erythematous aspect of the fundus. CMV was revealed by histological examination (typical cytopathic effect and immunostaining) and high viral load in the blood. The patient's immune balance was normal and the mother did not have any form of CMV infection. The diagnosis of primary CMV infection was retained in this immunocompetent child. Rectal bleeding disappeared without specific antiviral treatment. This observation points out that with rectal bleeding in an infant, cow's milk protein allergy should not be the only cause considered.