Increase in patients with Legionellasia, 2.5 times 10 years ago

The number of patients with Legionellosis, who are infected in bathing facilities with insufficient hygiene management, is increasing year by year. According to the National Institute of Infectious Diseases, 1,722 patients developed fevers and pneumonia due to infection last year, the highest number since 1999 when the current survey method was adopted. Care must be taken as severe cases can lead to death.

The number of patients has been increasing year by year since 2009, and in 2017 it was more than 2.5 times that of 10 years ago. By prefecture, Tokyo has the most cases, with 159. 109 in Hiroshima, 102 in Aichi, 101 in Kanagawa, 98 in Saitama, and 83 in Osaka. The reason for the increase is not clear, but it is pointed out that the diagnosis has become easier and the aging population.

Legionella, which causes legionellosis, lives in water and soil. It increases by invading hot water supply equipment, air conditioning cooling towers, and humidifiers. Infection occurs by inhaling droplets of water, causing fever, malaise, and pneumonia. In the 10 years to December 2016, a total of 10,310 cases were reported, including 196 deaths. Over 90% of patients were over 50 years old, and the mortality rate increased with age.

In March last year, 58 men and women in their 30s to 80s who used a bathing facility in Mihara City, Hiroshima Prefecture, contracted Legionnaires' disease, and one man in his 50s died. A subsequent survey pointed out the lack of hygiene management. At a facility for the elderly in Oita Prefecture, three people in their 80s and 90s were infected between December last year and January this year, and one died. A humidifier is suspected to be the culprit.

Bacteria grow best around 36 degrees. It dies at 60 degrees or more, and chlorine disinfection is also effective. New quinolone and macrolide antibiotics are effective for treatment, but early treatment is necessary. Junko Maekawa, senior researcher at the Department of Bacteriology, Department of Infectious Diseases, said, "If you develop symptoms such as a fever after using a bathing facility, please see a doctor."

http://www.asahi.com/apital/medicalnews/focus/ (Shuichi Doi)