A 77-year-old man has died of pneumonia caused by legionella bacteria at a public bath in Itabashi Ward, Tokyo, the health ministry said.
According to the Ministry of Health, Labor and Welfare, it is the first death in Japan caused by legionnaires' disease contracted in a public bath.
The ministry said Monday it will instruct prefectural governments nationwide to tighten hygiene controls at public baths.
According to the Itabashi Ward Office, the man ingested water after falling unconscious in a medicated bath at the facility on Dec. 27.
He was hospitalized immediately, but died of breathing difficulties related to pneumonia on Jan. 5.
The Tokyo Metropolitan Government hygiene research center detected the bacteria in the bath water and matched the DNA to that of bacteria obtained from the man, according to the ward office.
The danger of infection from baths with constant circulation systems for family use has become a nationwide problem, but the Itabashi facility drained and cleaned its tubs daily.
The sterilizing effects of chlorine may be weakened in medicated baths, however, and the center believes insufficient sterilization may have caused the infection.
Legionella, a bacterium found in nature, was discovered during an outbreak of pneumonia at an American Legion convention in Philadelphia in 1976. People can be infected by inhaling steam containing it.
Legionella can thrive in stagnant water, though it can be killed by heating water to over 70. Elderly people with weak immune systems are more likely to be infected than young people.