Detection by immune electron microscopy of 27-nm viral particles associated with community-acquired diarrhea in children

The proportion of diarrheal illnesses of unknown origin that were associated with small round virus (SRV, 23-38 nm) particles among children <2 years old attending an outpatient clinic in Baltimore was determined. During a 9-month period, stool specimens from 188 patients with acute diarrhea and 108healthy age-matched control children were examined for enteric bacterial pathogens, protozoa, enteric adenovirus, and rotavirus. An enteropathogen was identified in 75 patients (40%) and in 21 controls (20%). A random sample of specimens without an identifiable pathogen wasthen examined for SRV particles by immune electron microscopy (IBM) using com-mercial human gamma globulin. Viruses of26-30 nm diameter that were not enteroviruses were detected in specimens from 9 (12.5%) of the 7l patients and 1 (1.8%) of the 53 control subjects (P <.04). Of6 patients with available acute and convalescent sera, 4 demonstrated a significant immune response when tested by IBM. All patients experienced a mild, self-limited (1-3 days) illness. These findings suggest that SRV may beendemic in the Baltimore community and may result in clinically significant diarrheal illnesses. Studies of the etiology of diarrhea in the USA and else-where associate 40 %-60 % of episodes with an infectious agen