In infection tests of army recruits conducted as of 1911, the infection rate was found to be greater than 4% among individuals from Kagoshima Prefecture on Kyushu Island, with the infection found in as gar north as Aomori Prefecture.
明治44年（1911年）の段階の陸軍入隊者の感染検査で、鹿児島県九州本島部分出身者の感染率は4%を超えていたし、北は青森県まで感染者が確認されている。