In the summer of 1961, an outbreak of aseptic meningitis caused by Coxsackie B5 virus and to a lesser extent, by Coxsackie A9 virus took place in Aomori City and the adjacent rural communities. A total of 417 patients with aseptic meningitis in the epidemic were studied clinically and epidemiologically. Peak incidence was observed in July to August. Most patients distributed in infants and children under 10 years. The morbidity rate under 15 years of age was more than 500 per 100, 000 persons.
The predominant clinical manifestations of this outbreak were aseptic meningitis. However, one pleurodynia caused by B5 virus and one fatal case of uncertain etiology were found. No paralytic poliomyelitis was observed during the epidemic period. No significant differences were noted between the clinical features of aseptic meningitis caused by B5 virus and those by A9 virus, except that abdominal pain was more predominant in the former. Laboratory findings revealed significant elevation of amylase levels in serum and/or urine in 30.9% of the cases with B5 virus infection and 23.0% of the cases with A9 virus infection. This suggested that pancreatic involvement was not rare in the infections caused by either B5 or A9 virus.