Sir.—The recent report by Hall et al (Am J Dis Child 131:323, 1977) on the return of the "Boston exanthem agent" is of interest in light of findings of the Enterovirus Surveillance System, a coordinated channel for reporting of isolations of non-polio enteroviruses by state laboratories to the Center for Disease Control (CDC). General data for 1971 through 1975 have been reported,1 and more specific information is being readied for publication.
As Hall and colleagues state, since the 1950s echovirus 16 had scarcely been seen in the United States. However, in 1974, 12 of 19 states reporting echovirus isolates made 173 isolations of echovirus 16. Twelve percent of the isolations were made in June, 27% in July, 34% in August, and 15% in September. The male to female ratio was 1.68. When age-adjusted and expressed as 10 million persons per age-interval, incidence was inversely related to age: 689 for