Abstract
The status of outbreaks of poliomyelitis patients from 1956 to 1958 and neutralizing antibodies against the 3types of poliomyelitis virus in the normal population in 1957 and 1958 of Gifu Prefecture were investigated.
1) Although 117 cases were recognized in infants under 15 years old, attack rate was 88% under 5 years old and 60.7% in the 7/12 to 2 year group.
2) The majolity of patients broke out in summertime and seasonal index was 2.1 in 1956, 2.7 in 1957, and 5 in 1958, respectively.
3) Age distribution of neutralizing antibodies indicated that level of antibody was lowest in infants aged 7/12 to 2 years (no antibody except 16.6% for Type I), after which it jumped to 30-50% in the 3 to 5 years and the level of positives increase to 92.7% for Type I, 85.7% for Type II, and 75% for Type III over 16 years old.
4) The highest incidence and the lowest level of antibodies were both in the 7/12 to 2 year age group. It was recognized that decrease of incidence and increase in antibodies were nearly pararell with age, and some relation between attack rate and distribution of antibodies was exist.
