Illustration=ChatGPT DALL·E 3

As the weather gets hotter, cases of Legionnaires' disease are increasing. Legionnaires' disease is a class 3 infectious disease caused by the Legionella bacteria that inhabit air conditioning cooling water and is transmitted through the air to the respiratory system. The symptoms are similar to those of influenza and pneumonia and can lead to renal failure or, in severe cases, death.

According to the Korea Disease Control and Prevention Agency on the 14th, there have been 165 cases of Legionnaires' disease in South Korea this year. This is a 47% increase from the same period last year (112 cases). The age group of patients is predominantly over 60, accounting for 9 out of 10. The occurrence areas, in order, are Gyeonggi Province (41 cases), Seoul (39 cases), South Gyeongsang Province (14 cases), North Gyeongsang Province (13 cases), and Daegu (11 cases).

Cases of Legionnaires' disease have surged in the past 20 years. Rising temperatures due to climate change have increased the use of air conditioning, leading to a corresponding rise in cases. The number of patients with Legionnaires' disease was only 6 in 2005 but increased to 452 last year. It first reached triple digits in 2016 with 128 cases, rising to 305 in 2018, when a heatwave struck the Korean Peninsula, and to 501 in 2019. The number has remained at the 400 range for the past three years.

Graphic=Jeong Seo-hee
Graphic=Jeong Seo-hee

Legionnaires' disease was first confirmed in 1976 when more than 200 patients emerged at a convention of U.S. veterans, with over 30 dying. It was revealed that the bacteria were transmitted through the air conditioning of the hotel where the veterans were staying, thus naming the infection Legionnaires' disease.

The symptoms of Legionnaires' disease are similar to those of influenza or pneumonia. When showing influenza symptoms, an acute fever can appear with an incubation period of 5 hours to 3 days. Recovery is possible over time without special treatment. When showing pneumonia symptoms, the incubation period is 2 to 10 days. Symptoms include headache, high fever, chills, dry cough, abdominal pain, and diarrhea, and severe cases can lead to death.

Anyone can contract Legionnaires' disease, but individuals with diabetes, hypertension, lung disease, smokers over 50, and the elderly are particularly vulnerable. The most effective way to prevent Legionnaires' disease is to inhibit the proliferation of Legionella bacteria.

Legionella bacteria inhabit water sources such as air conditioning cooling water, baths, and water supply facilities. Breathing in bacteria carried by droplets can cause Legionnaires' disease. The Korea Disease Control and Prevention Agency noted, 'Legionnaires' disease shows symptoms similar to colds or novel coronavirus infection (COVID-19),' and emphasized that 'air conditioners, showerheads, faucets, misting systems, and building cooling water should be regularly cleaned and disinfected.'