Natural history and prognosis of diarrhoea of unknown cause in patients with acquired immunodeficiency syndrome (AIDS).

This paper is a prospective study of patients with advanced human immunodeficiency virus infection and chronic diarrhoea for which no cause could be found after extensive investigations, including examination of multiple stool specimens for all known faecal pathogens and the histological examination of small and large bowel biopsy specimens. Of 39 such patients recruited from 155 prospectively investigated patients, eight had a possible cause of diarrhoea identified on follow up investigations, including small bowel neoplasms in three and cytomegalovirus in two. In 17 of the remaining 31 the diarrhoea resolved completely in a mean of seven months from its onset. Eleven had continuing mild or intermittent diarrhoea and three had more than 1 litre of diarrhoea daily for which no cause could be found. The median survival for patients with 'pathogen negative' diarrhoea was 48.7 months, which is similar to that of control patients with no diarrhoea and significantly longer than that of matched patients with a gastrointestinal pathogen (9.6 months).