( CNN ) -- A Las Vegas resort is warning some former guests that they may have come in contact with high levels of the legionella bacteria , which causes Legionnaires ' disease , a form of pneumonia , the hotel announced Thursday . The Aria Resort and Casino in Las Vegas is telling guests who stayed at the Aria from June 21 to July 4 , 2011 , that they may need to be tested for the bacteria , according to a letter to guests from Paul Berry , the hotel operations ' vice president . Water tests at that time indicated high levels of the bacteria in several guest rooms . The hotel -- part of a vast collection of hotel rooms , condominiums and its own shopping center in Las Vegas ' CityCenter -- has been connected in the past with six cases of Legionnaires ' disease , said the Southern Nevada Health District . The district identified the six cases beginning in the spring of 2010 , said Jennifer Sizemore , a manager at the health district . The hotel regularly inspects their water supply with a series of tests ; the health district only gets involved when there are cases of illness or elevated levels of bacteria reported , said Sizemore . The health district contacted the hotel after the first reported case and `` inspected their water system ... they had everything in place that needed to be , '' said Sizemore . `` There was n't evidence at that time that indicated they had ( the bacteria ) . '' From the six reported cases of Legionnaires ' disease , all six had healthy recoveries , said Sizemore . Guests before the reported window of June 21 to July 4 are past the incubation period of the bacteria , so any symptoms they would 've shown are past , said Sizemore . The usual symptoms of Legionnaires ' disease include fever , chills , muscle aches and headaches , which are similar to pneumonia , so the disease may be difficult to diagnose , according to the health district . The hotel advised guests who have experienced these symptoms to seek medical attention . Symptoms show up between two to 14 days after exposure and it is contracted through exposure to contaminated water or when an individual breathes in a mist or vapor , the health district said . The health district said the bacteria is found most usually in water , such as hot and cold water taps , hot water tanks and water from air-conditioning systems . It ca n't be acquired through contact with people , said the health district . `` We 're working to replace fear and anxiety with facts and information , '' said Gordon Absher , vice president of public affairs for MGM Resorts International , which runs the Aria resort . The most recent tests indicate the bacteria was not present in any detectable way , but tests will continue , Berry said . The Aria , completed in 2009 , is a 4,004-room , 568-suite resort that also has an on-site casino and spa .
A Las Vegas resort is contacting guests who may have encountered bacteria . Six cases of Legionnaires ' disease from 2010 have been identified from the hotel . Symptoms of the disease include fever , chills and headaches .