Iiyuratei hot spring in Niigata found with extreme Legionella levels

Authorities in Sanjo, Niigata Prefecture, have reported significant sanitation violations at the Iiyuratei hot spring facility. Water samples taken from the Waraku no Yu area revealed Legionella bacteria levels at 2,000 colony-forming units per 100 ml, which is 200 times the regulatory limit of 10 units.

The investigation follows reports of an individual contracting Legionella pneumonia after using the facility in early September. While officials have not yet confirmed a direct causal link between the facility use and the specific illness, the bacterial levels are critically high. Legionella pneumophila is a major cause of community-acquired pneumonia, which can lead to severe symptoms such as high fever, chest pain, and even death if untreated.

Records indicate a pattern of negligence at the facility. Between April 2020 and 2026, the onsen had been found to have Legionella levels exceeding limits on 49 separate occasions. Despite these repeated findings, the facility reportedly failed to suspend the use of the affected baths as required by regulations.