During an 8-year study period, Arcobacter butzleri was the fourth most common Campylobacter -like organism isolated from 67,599 stool specimens. Our observations suggest that A. butzleri displays microbiologic and clinical features similar to those of Campylobacter jejuni ; however, A. butzleri is more frequently associated with a persistent, watery diarrhea.

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To determine the relative importance of two known serotypes of human rotavirus, we developed an enzyme-linked immunosorbent assay to differentiate serotype-specific rotavirus antigen and antibody. Using this technic, we studied the epidemiology of the two serotypes in acute gastroenteritis. Seventy-seven per cent of 414 rotavirus isolates were Type 2, and the remainder were Type 1. The serotype distribution was similar in specimens from children in Washington D.C., and other parts of the world. Sero-R OTAVIRUS is an important cause of gastroenteritis of infants and children in many parts of the world.'' 2 Because the virus does not grow effi-ci,ently in tissue culture, conventional neutralization "methods cannot be used to examine its serotypic variations.''' Recently, two human rotavirus serotypes were distinguished by complement fixation,' immune electron microscopy' and immunofluorescence. 6 The latter two methods are not practical for serotyping of large numbers of rotavirus-positive specimens whereas complement fixation is not sensitive enough for use with low-titered preparations. We recently described the technic of enzyme-linked immunosorbent assay for the detection of rotavirus antigen and antibody.'"" This assay is similar in design to radioimmunoassay but uses an enzyme instead of a radioactive isotope to quantitate binding of immunoglobulin. We modified the basic assay for detection of rotavirus serotypes and used this new procedure to study the epidemiology of these viruses. MATERIALS AND METHODS Specimens'Stool specimens containing rotavirus were collected from 278 in-il. nts and children with gastroenteritis living in the Washington, D.C., area. From January, 1974, to October, 1976, only hospitalized patients were studied, whereas from November, 1976, to May, 1978, specimens from both inpatients and outpatients were available. This population has been described in detail.' In addition, 136 rotaviruscontaining specimens were available from children with and without gastroenteritis from other localities throughout the world. Included were rotavirus-positive stool specimens obtained

D. fragilis and G. lamblia were the most frequently encountered parasites in our study population. Improved diagnostic tests are essential tools to study the prevalence and pathogenesis of D. fragilis.