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[AAS09-10] Impacts of climate change on reported Legionnairs' disease searched with the weekly reported numbers
Keywords:climate change, Legionnaires' disease, seasonal change, extreme events
Legionnaires' disease is a respiratory infection caused by Legionella bacteria (Legionella spp.) that live in water and wet soil, and is transmitted through the respiratory tract by aerosols containing the bacteria. It grows at 20-45 degree C., and mass infections have often been reported at artificial water facilities such as spas and air-conditioning cooling systems. In addition, the number of cases may increase after floods and landslides since it could lead to increases in aerosols containing the bacteria. Hence, Legionnaires' disease would increase due to the intensification and more frequent extreme weather events caused by global warming.
In this study, we derived an average seasonal change of Legionnaires' disease in each prefecture from 2009 to 2019 using the Infectious Disease Weekly Report Japan by the National Institute of Infectious Diseases. The number of reports increases in summer and autumn at a nationwide scale, showing that the peaks shift from early summer in Okinawa to autumn in Hokkaido in accordance with the geographical distribution of climate. Those agree with the optimum environment for Legionella spp. multiplication. We also examined the number of Legionnaires' disease reports after the noticeable disasters. The meteorological extreme events were chosen from the weather disaster reports by the Japan Meteorological Agency. Our analysis showed that the number of reported cases of Legionnaires' disease tended to increase after the meteorological extreme events caused by the combinations of typhoons and fronts particularly that lead to many cases of flood damage.
Furthermore, the annual number of the cases of Legionnaires' disease is increasing year by year. We will further examine impacts of long-term climate changes on it.
In this study, we derived an average seasonal change of Legionnaires' disease in each prefecture from 2009 to 2019 using the Infectious Disease Weekly Report Japan by the National Institute of Infectious Diseases. The number of reports increases in summer and autumn at a nationwide scale, showing that the peaks shift from early summer in Okinawa to autumn in Hokkaido in accordance with the geographical distribution of climate. Those agree with the optimum environment for Legionella spp. multiplication. We also examined the number of Legionnaires' disease reports after the noticeable disasters. The meteorological extreme events were chosen from the weather disaster reports by the Japan Meteorological Agency. Our analysis showed that the number of reported cases of Legionnaires' disease tended to increase after the meteorological extreme events caused by the combinations of typhoons and fronts particularly that lead to many cases of flood damage.
Furthermore, the annual number of the cases of Legionnaires' disease is increasing year by year. We will further examine impacts of long-term climate changes on it.