Background: Persons infected with human immunodeficiency virus (HIV) are at
increased risk for diarrhea and enteric infections. We studied (1) the epi
demiology of enteric pathogens associated with diarrhea, (2) the diagnostic
yield of stool examination and endoscopic evaluation, (3) risks to develop
diarrhea, and (4) the impact of diarrhea on patients' survival.
Methods: A total of 1933 participants in the Swiss HIV Cohort Study were pr
ospectively followed up for a median of 25.5 months. A total of 560 diarrhe
al episodes were evaluated by standardized stool examination. Endoscopic ev
aluation was performed in 25% of patients with chronic diarrhea.
Results: The incidence of diarrhea was 14.2 per 100 person-years (95% confi
dence interval, 13.0-15.4). Among patients with CD4 cell counts below 0.05
X 10(9)/L, the probability to develop diarrhea within 1, 2, and 3 years was
48.5%, 74.3%, and 95.6%, respectively. The risk to develop diarrhea was in
creased among patients with severe immunodeficiency, homosexual men, and pa
tients taking antiretroviral therapy. Pneumocystis carinii chemoprophylaxis
did not reduce the risk of diarrhea. Diarrhea was an independent negative
predictor of survival. Enteric pathogens were detected in 16.5% of 212 acut
e diarrheal episodes and in 46% of 348 chronic diarrheal episodes. The sens
itivity of histological and stool examination was similar except for the di
agnosis of intestinal cytomegalovirus infection and leishmaniasis, which re
quired invasive evaluation.
Conclusions: Intestinal infections were diagnosed in less than 50% of chron
ic diarrheal episodes. The prevalence of enteric pathogens tended to decrea
se during the observation period, possibly because of improved antiretrovir
al therapy. Endoscopic evaluation did not improve the diagnostic yield comp
ared with stool examination except for the diagnosis of cytomegalovirus ent
eritis and leishmaniasis.