"Probable cases" are persons presenting with symptoms of the disease, including a diagnosed pneumonia in some but without laboratory confirmation.
"Based on epidemiological evidence We have an outbreak among people who have stayed at the (Sheraton Atlanta) during the same period," she said. Guests complaining of lung problems and later diagnosed as "legionnaires" had attended a meeting at the hotel in Atlanta a few weeks ago.
The bacterium causing legionnaires was not confirmed at the hotel. The hotel has commissioned external experts to conduct tests. The State Department of Health, the Fulton County Health Department and environmental specialists are also working with the hotel to test the bacteria. More than 400 guests were relocated to nearby hotels, CNN subsidiary WSB-TV reported. Both on 19 July and on Monday environmental samples were taken. The results are still pending as the test lasts up to 14 days.
"This is the typical way to deal with these situations, because the assessment and testing can be complicated," says Nydam. The state health department and other authorities will work with the hotel on the next steps of the investigation.
Thousands of infected people per year
In addition to relocating current guests to nearby hotels, the Sheraton also appeals to guests with upcoming reservations, according to Ken Peduzzi, the hotel's general manager.
"All guests with forthcoming reservations by August 11 have been notified of the hotel's temporary closure and are working with Marriott and Sheraton Atlanta to find alternative accommodation, guests who have their reservations canceled will receive a full refund", James Francey, one of more than 400 resettled guests, told WSB: "This is a danger to the trip … so alright, it happens, the CDC is in town, that's great." 
Symptoms of Legionnaires' Disease
Described as "severe, often fatal form of pneumonia". According to Legionella.org, legionnaires can be treated for intensive care. Some symptoms may be long-term: One study showed that three quarters of the survivors continued to feel tired, 66% had neurological symptoms, and 63% had neuromuscular symptoms months after their diagnosis.
Scientists called the disease "Legionnaire's Disease" an outbreak in Philadelphia in 1976, especially among participants in a State Congress of the American Legion.
Legionella are naturally found in the environment and grow best in warm water. According to Georgia, they are found in shower heads and faucets, whirlpools, cooling towers, hot water tanks, decorative fountains or sanitary systems in large buildings Ministry of Health.
In Georgia, 189 cases of Legionnaires' disease were reported in 2018 and 172 cases in 2017.