Las Vegas Legionnaires’ Outbreak

The Southern Nevada Health District announced that the Las Vegas Legionnaires’ outbreak has risen to seven cases – with 29 more suspected – five months after the outbreak was reported at the Rio All-Suite Hotel and Casino in Las Vegas.

There also are 56 suspected cases of Pontiac fever, which is a flu-like illness caused by Legionella bacteria, which causes Legionnaires’ disease. Unlike Legionnaires’ disease, Pontiac fever does not cause pneumonia (see below). The 56 cases increase the total to 92 confirmed or suspected cases of Legionella illnesses related to the outbreak.

In June, two visitors contracted Legionnaires’ disease after staying at the Rio All-Suite Hotel and Casino separately in March and April. Testing of the hotel’s hot-water system in May confirmed the presence of Legionella.

“The health district continued to receive notifications of the illnesses from hotel guests who left Las Vegas and were diagnosed in their hometowns,” said Kimberly Hertin, the SNHD surveillance supervisor.

Cleaning and monitoring the hotel’s water system is ongoing. All recent tests of the hotel’s water systems showed low levels or no presence of Legionella. A precautionary third disinfection took place Nov. 3.

“The entire Rio property is open, and we have remediated all water sources,” the Rio said in a statement. “We continue to work with the Southern Nevada Health Department and have taken the additional step of voluntarily installing a new filtration system to help prevent a reoccurrence.”

Legionnaires’ or Pontiac fever?

Legionnaires’ disease, which is also known as Legionellosis or Legionella pneumonia, is a severe type of pneumonia (lung infection). According to the Centers for Disease Control and Prevention (CDC), about 25,000 cases of Legionnaires’ disease occur each year, but only 5,000 are reported because of the disease’s non-specific signs and symptoms. In addition, 10 percent of those cases will end in death.

Pontiac fever, on the other hand, produces symptoms that can include a fever, chills, headache, and muscle aches. Pontiac fever, however, doesn’t infect the lungs.

Legionella in the air 

Legionella bacteria are contracted by inhaling microscopic water droplets in the form of mist or vapor. The bacteria grow best in warm water and are primarily found in human-made environments.

Legionnaires’ disease outbreaks have been linked to numerous sources, such as:

• water systems, such as those used in hotels
• cooling towers in air-conditioning systems
• decorative fountains
• mist machines
• hot tubs/whirlpools
• hot-water tanks and heaters
• large plumbing systems
• showers and faucets
• swimming pools.