Trends in the incidence and mortality of legionellosis in Japan: a nationwide observational study, 1999–2017

Abstract

This study examined temporal trend, seasonality, and geographical variations of legionellosis incidence and mortality in Japan. This nationwide observational study used the Japanese Vital Statistics and Infectious Diseases Weekly Report (1999–2017) data to calculate legionellosis crude and age-adjusted incidence and mortality rates per 100,000 population by age and sex. Incidence was compared among the 4 seasons and regional incidence among 47 prefectures. Of 13,613 (11,194 men) people with legionellosis in Japan, 725 (569 men) were fatal. Increasing incidence trend occurred from 0.0004 (1999) to 1.37 (2017) per 100,000 population. People aged ≥ 70 years accounted for 43.1% overall; men’s age-adjusted incidence rate was consistently approximately five times higher than for women. Significantly higher incidence occurred in summer than in winter (p = 0.013). Geographically, highest incidence (≥ 2.0 per 100,000 population) occurred in Hokuriku District, with increasing trends in Hokkaido and middle-part of Japan. Estimated fatality rates decreased consistently at 5.9% (95% confidence interval: − 8.1, − 3.5) annually, from 1999 to 2017, with no trend change point. Increasing legionellosis incidence occurred in Japan during 1999–2017, with declining estimated fatality rates. In this aging society and warming world, disease clinical burden may further deteriorate in future due to increasing incidence trends.

Climate change and opportunistic pathogens (OPs) in the built environment

“…Warming is expected to enhance survival and propagation of OPs in the natural and built environment (Blanc et al, 2021;Walker, 2018). Seasonal increases in legionellosis observed in the late summer to early autumn in the northern hemisphere may start earlier and last longer due to climate change (Alarcon Falconi et al, 2018;Fischer et al, 2022;Fukushima et al, 2021;Park et al, 2019). The association between warmer weather and incidence of legionellosis is well documented, and increased legionellosis cases may lag a period of elevated temperatures by several weeks (Beauté et al, 2016;Brandsema et al, 2014;Fisman et al, 2005;Han, 2019;Passer et al, 2020;Simmering et al, 2017).…”

“…In Ontario, just three OPs, nontuberculous mycobacterium (NTM), Legionella spp., and Pseudomonas spp., represented 83% of hospitalizations and 97% of deaths attributable to a known waterborne pathogen (Greco et al, 2020). In the United States, the estimated cost of treating diseases caused by these OPs range from around $1.5 to $2.4 billion per year, and NTM-related infections are increasing (Donohue et al, 2015;Falkinham, 2020;Proctor et al, 2022) as are cases of legionellosis in many other countries (Cassell et al, 2021;Fischer et al, 2022;Fukushima et al, 2021). This may be further exacerbated by climate change (Health Canada, 2022).…”

Infectious disease activity during the COVID-19 epidemic in Japan: Lessons learned from prevention and control measures

“…Public health centers report to the prefectural government and the Ministry of Health, Labor, and Welfare via an online reporting platform. Since 1999, the National Institute of Infectious Diseases has collected and analyzed clinical data from the platform and published the Infectious Disease Weekly Report (IDWR) (14,15).…”

Factors That Affect Legionella Positivity in Healthcare Building Water Systems from a Large, National Environmental Surveillance Initiative

“…Legionellosis is increasing in the United States (U.S.), and Legionella species caused the most drinking water outbreaks reported in the U.S. in 2013–2014 . Reports from other countries also indicate increasing incidence, , though comparison of incidence worldwide is complicated by underdiagnosis of cases and differing reporting criteria.…”