Epidemiological study of an "hand-foot-and-mouth disease" outbreak observed in Rome in the fall of 1973

An outbreak of "hand-foot-and-mouth disease" (HFMD) occurred in Nov. 1973 in a nursery school. Sixty-seven children were studied, 15 of whom presented clinical signs of the disease. Sixty-two percent of the HFMD cases and 18% of asymptomatics were proved to be infected with Coxsackie virus A 16. The ratio of clinical to asymptomatic infection of nursery-school children with confirmed Coxsackie A 16 infection was 58%. The accidental diffusion of the infection led to the occurrence of secondary cases. This allowed to establish the incubation period of the illness at 8 to 12 days, for 3 individual cases where a single infecting contact in a very definite time could be documented. Fecal excretion of virus was demonstrable in 2 cases up to 10-20 days, while the duration of oral excretion appeared to be somewhat shorter. Evidence was also obtained showing that infectious virus could be spread by patients during the incubation period. Virus isolations were more easily obtained in suckling mice than in cell culture.