The bacterium is found naturally in the environment, but it multiplies rapidly in hot water. Authorities believe hotel guests may have been exposed through the shower system by breathing in the bacteria-ridden vapor.
"We increased our testing program when we got that information," said Vice President of Public Affairs Alan Feldman. "And we found elevated levels of Legionella in a couple of rooms."
The Southern Nevada Health District says six cases of the potentially fatal infectious disease have been reported. All six people have been treated and recovered.
As a top new draw with more than 4,000 rooms, Aria Resort and Casino attracts thousands of visitors. Aria posted on its website the letter it sent to the 18,000 guests who stayed at the resort from June 21 to July 4.
That's when hotel officials say water tests detected elevated levels of Legionella bacteria in about half a dozen guest rooms.
"It was all the same room type," said Feldman. "But again, in an abundance of caution, it's best to go through the whole property."
This past February, a couple hundred people ended up sick after a party at the Playboy Mansion. According to county health officials Legionella was likely the cause.
Symptoms usually show up two to 12 hours after exposure and include:
- High fever
- Muscle aches
The illness usually occurs when someone is directly exposed to the bacteria when breathed in as a mist or vapor.
"Whirlpools, shower heads, Jacuzzis, anything where the water can be vaporized will cause the Legionella to get inhaled and cause pneumonia," said Dr. Jon Willen from Northridge Hospital Medical Center.
If you are sick you're urged to call your doctor. Most cases are treated successfully with antibiotics.
As for the hotel, officials say all subsequent water tests have come back clean. Aria has set a toll-free number for guests to call, 877-326-ARIA.