Mr. Li, around 50, was a manager of a commercial group. The other day, he went to attend a business meeting in a star-rate hotel. It happened to be the peak of the summer, when the sun was scorching relentlessly, while inside the meeting room, the air-conditioner blows gentle wind that pleased all the participants.

Returning home from the meeting, Mr. Li got indisposed, and was troubled in the evening with headaches, lassitude, soreness in the whole body, and a poor appetite. The next day when his body temperature reached 39℃, Mr. Li found himself subject to the shivers, muscle pains, as well as dry coughs, and blood phlegm which would not be retrieved until he had received several days’ treatments in the hospital. And he heard that many participants of that meeting had got similar symptoms. Later, when water supply system of the central air-conditioner was being cleaned in the hotel, large amount of iron rusts and some other pollutants were found. And no similar cases have ever been seen since the water supply system was completely cleaned and disinfected. It turns out to be the pollutants in the water supply system of the central air-conditioner that had made Mr. Li and other people infect a certain disease which is named after Legionnaires Disease

Legionnaires Disease is usually contracted through Legionnaire Bacillus infection. It was firstly recognized, in July, 1976, on the 56th American Veteran Annual Convention in Philadelphia, where 182 participants of the meeting caught pneumonia, of which 29 died. This event once caused a panic among the local people. Later, a certain bacterium was separated from the lung tissues of the patient. This bacterium, which was found to be originated from the air-conditioning system of the hotel, was named after Legionella Pneumophila by the medical community, and the disease caused by this bacterial was called Legionnaires Disease. This disease is pervasive across the whole world. Since the first Legionnaires Disease case was detected in 1981 in China, it has been witnessed in all the other provinces except Tibet Autonomous Region,.