ENTERIC VIRUSES AND DIARRHEA IN HIV-INFECTED PATIENTS

Background. Diarrhea occurs frequently among persons with the acquired immunodeficiency syndrome, but the cause often remains unknown. We used a group of diagnostic assays to determine which viruses were etiologic agents of diarrhea in a group of persons infected with the human immunodeficiency virus (HIV). Methods. Stool and serum specimens were obtained from HIV-infected patients enrolled in a longitudinal study in Atlanta. Fecal specimens from patients with diarrhea and from control patients without diarrhea were screened by electron microscopy, polyacrylamide-gel electrophoresis, and enzyme immunoassays for rotaviruses, enteric adenoviruses, caliciviruses, picobirnaviruses, and astroviruses. Paired serum samples were tested for antibody responses to Norwalk virus and picobirnavirus. Results. Viruses were detected in 35 percent of 109 fecal specimens from patients with diarrhea but in only 12 percent of 113 specimens from those without diarrhea (P<0.001). Specimens from patients with diarrhea were more likely than those from patients without diarrhea to have astrovirus (12 percent vs. 2 percent, P = 0.003); picobirnavirus (9 percent vs. 2 percent, P = 0.017); caliciviruses, including small round structured viruses (6 percent vs. 1 percent, P = 0.062); and adenoviruses (9 percent vs. 3 percent, P = 0.047). They were also more likely to have a mixed viral infection (6 percent vs. 0 percent, P = 0.006). With the use of polyacrylamide-gel electrophoresis to analyze concentrated RNA extracts from stool, picobirnavirus was detected in fecal specimens from 6 of the 65 patients with diarrhea and was associated with prolonged viral shedding and chronic diarrhea. No rotaviruses, enteric adenoviruses, or instances of seroconversion to positivity for Norwalk virus were observed. Conclusions. Novel enteric viruses such as astrovirus and picobirnavirus may be more important etiologic agents of diarrhea in HIV-infected patients than previously recognized and may be more common than either bacterial or parasitic enteropathogens.