Epidemiology and Etiology of an Influenza Epidemic Experienced at Camp Iwate of the Ground Self Defence Force in 1959

Abstract

An influenza epidemic occurred around the end of March, 1959 at Camp Iwate of the self defence force stationed in Takizawa village which lies about 20 km north of Morioka City. Out of 1, 223 soldiers, 363 contracted the disease, the morbidity rate being 29.7%.
The epidemic began soon after the arrival of a new group of soldiers from Camp Hachinoe in Aomori Prefecture. Out of 117 soldiers of B company joined by 15 of the new arrivals, 51 (43.6%) contracted influenza.
Serological tests with the convalescent sera revealed that 9 of the 27 sera tested gave high agglutinin titer against A₂ type virus, while all the sera tested showed any rise of the antibody titer neither against A type nor against B type of the virus. Six influenza viruses were isolated by both amniotic and allantoic inoculation of fertile eggs. All of these were revealed to be antigenically similar to A₂ type strain.