Outbreak of Legionnaires’ disease in Napa County sickens 12, killing 1

A sign in front of a vineyard says "Welcome to this world famous wine growing region, Napa Valley"
A welcome sign greets visitors along St. Helena Highway in Napa Valley.
(Jay L. Clendenin / Los Angeles Times)

Authorities in Napa County are investigating an outbreak of Legionnaires’ disease that sickened 12 people, killing one of them, over the last three weeks.

The severe lung infection is caused by exposure to contaminated water or mist, and most outbreaks are linked to cooling towers, part of an air conditioning system that releases mist. Without proper cleaning, cooling towers can create the ideal environment for Legionella bacteria to grow.

Testing found high levels of the bacteria in a sample taken from a cooling tower at the Embassy Suites Napa Valley hotel in the city of Napa, public health officials said Wednesday, though other sources of Legionella in the area are possible.

“The cooling tower has since been taken offline, which mitigates any ongoing risk to public health,” officials said.

Of the 12 people sickened since July 11, three remained hospitalized, officials said. The person who died was older than 50 and had risk factors for severe disease.


None of the patients, who are all Napa County residents, had stayed at or visited the Embassy Suites Napa Valley, public health officials said.

In what became one of the nation’s biggest Legionnaires’ disease outbreaks, 22 people fell sick with the dangerous lung infection last fall in Orange County, including one who died.

Sept. 6, 2018

Investigators with Napa County Public Health, the California Department of Public Health and the federal Centers for Disease Control and Prevention are working to identify any additional sources of water that might contain the bacteria in unsafe amounts, officials said.

“Our joint investigation team continues to work with Embassy Suites staff to remediate the source of exposure,” said Dr. Karen Relucio, Napa County health officer. “Finding Legionella in one water sample is an important piece of the puzzle, but we must continue to investigate other cooling towers and water sources in the outbreak area, as it is common to find more than one source.”

Authorities warned county residents and people living or working in Napa who have flu-like symptoms, cough, fever or difficulty breathing to contact their healthcare provider as soon as possible.

Legionnaires’ disease is contracted by breathing aerosolized water containing the bacteria and is not spread from person to person, officials said. It can be treated with an antibiotic when caught early.

In addition to coming from cooling towers, the small water droplets can be produced by hot tubs, cooling misters, decorative fountains and plumbing systems, officials said.


Residents can prevent the bacteria from growing in their homes by flushing faucets and shower heads if they haven’t been used recently, and by cleaning, disinfecting and maintaining all devices that use water, officials said.