Etiologic studies of the 1983 and 1984 outbreaks of epidemic diarrhea in Guangxi.

Studies are reported on two outbreaks of epidemic diarrhea in China involving 19,007 patients. The first outbreak occurred in the northern part of the Guangxi Autonomous Region and extended south from April through September 1983. In June 1984 a second outbreak of 6,570 cases occurred in Guanyang, a county in the northern part of Guangxi. 125 fecal samples from the two outbreaks were cultured for bacteria; all of the samples except one were negative. Rotavirus particles were detected in 44.1% (15/34) of stool specimens examined by immune electron microscopy. The two outbreaks appeared to be caused by non-group-A rotaviruses, based on the pattern of electrophoretic migration of the RNA genome segments in polyacrylamide gels and on the lack of a detectable common group antigen(s) when tested by an enzyme-linked immunosorbent assay for group A rotaviruses. Complement-fixation tests also indicated that 37.5% of convalescent-phase sera from patients produced antibody to the isolated rotavirus. The total molecular weight of the RNA segments in the new Guangxi strain was calculated to be 10.69 X 10(6), with the 11 genome segments having molecular weights (X 10(6)) of 2.19, 1.83, 1.56, 1.53, 0.82, 0.81, 0.60, 0.46, 0.35, 0.30, and 0.24. This study also reports comparative detection rates for direct and immune electron microscopy and for PAGE. PAGE proved to be the most sensitive detection method for these new rotaviruses.