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Update: One dead, three hospitalized from Legionnaires' disease in Napa County; bacteria found on hotel property

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Updated at 4 p.m. Thursday  Napa County public health authorities are investigating the largest local outbreak of Legionnaires’ disease in several years — with one resident dead, others hospitalized, and disease-causing bacteria found in a hotel’s cooling tower.

One local resident has died after contracting the waterborne microbe, and another 11 have fallen ill since July 11, the county announced late Tuesday.

Wednesday evening, Napa County’s Health & Human Services agency confirmed the Legionella bacterium that causes the disease was detected in preliminary samples taken from a rooftop cooling tower at the Embassy Suites by Hilton Napa Valley, at 1075 California Blvd. in the city of Napa.

None of the people sickened in the latest outbreak, which began July 11, are known to have visited or stayed at the Embassy Suites. All of the patients have been local residents, with most living in Napa near the hotel but at least one in Calistoga, county Public Health Director Dr. Karen Relucio said. (The Calistoga resident has a history of visiting Napa, she added.)

Legionella bacteria, which are waterborne, can spread in aerosols for up to a mile from a contaminated water source, according to Relucio.

Interim County Public Information Officer Leah Doyle-Stevens said Thursday that's why the county believes the cooling tower could have been the source of infection, given that those most of those infected live near the hotel. But, she added, the county is continuing to investigate nearby cooling towers, spas and other areas that may be serving as sources of infection. 

Three of the people sickened in the Napa County outbreak are currently hospitalized, one is on a ventilator, and eight have recovered, Relucio told reporters outside the county health department offices. 

The patients range in age from 58 to 80 with an average age of 69, and most are men, according to Relucio. Many also had existing health conditions such as lung disease, kidney problems or diabetes, which she said is consistent with patients older than 50 and with weakened immune systems being most vulnerable to contracting Legionnaires’ disease.

“These were not healthy people with no underlying conditions,” she said.

“The cooling tower has since been taken offline, which mitigates any ongoing risk to public health,” she said, adding that Napa County continues to look into any other artificial water fixtures – such as decorative fountains or cooling towers for commercial air conditioning systems – that may harbor unsafe levels of the bacteria.

“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,” Relucio said Wednesday.

County officials are discussing a targeted outreach to residents of the neighborhood near the Embassy Suites hotel, which is near Highway 29’s interchange with First Street, according to Patty Martinez, a Napa County health education specialist.

An Embassy Suites spokesperson said in a statement Thursday that the hotel is working closely with health officials on their investigation, and "continues to make every effort to ensure all practices and standards are in line with strict safety and security regulations."

Once the hotel became aware of the preliminary findings of Legionella in the cooling tower, the spokesperson said, "we immediately contacted our consultant and water treatment provider to ensure we were following the guidance set forth by the health department and began remediation."

Health officials in Napa County first confirmed nine probable Legionnaires' cases on July 29. One or two cases in Napa County per year are typical, although the risk to residents and visitors remains low despite the recent outbreak, county officials said last week.

The fatality was the first to be recorded from Legionnaires’ disease in Napa County since at least before Relucio’s appointment as public health officer in 2015.

Legionella, the bacterium that causes the disease, grows in warm water. While the microbe naturally occurs in lakes and streams, it can become a health threat when it contaminates artificial water systems such as cooling towers for air conditioning in buildings or decorative fountains. Incubation of Legionella bacteria can take from two to 14 days, according to Relucio.

“Outbreaks are commonly associated with buildings or structures that have complex water systems, like hotels and resorts, long-term care facilities, hospitals, and cruise ships," according to the U.S. Centers for Disease Control and Prevention. “The most likely sources of infection include water used for showering, hot tubs, decorative fountains, and cooling towers."

Napa County Public Health is working closely with a joint investigation team from the California Department of Public Health, U.S. Centers for Disease Control and Prevention, and the Napa County Environmental Health Branch of the Planning Building and Environmental Department, the county said. Authorities are sampling water for Legionella and recommending remediation strategies where appropriate to prevent further transmission.

Symptoms of Legionnaires' disease include fever, chills, nausea, vomiting muscle aches and cough. It is not transmitted person-to-person, only from breathing in water vapor containing the bacteria. There is no danger from most home air conditioning units, which do not use water vapor for cooling.

People at a higher risk for serious illness include those over 50, cigarette smokers, and people with chronic lung disease or compromised immune systems. Legionnaires' disease is treatable with antibiotics.

Relucio advised people with possible symptoms and health risk factors to avoid being outside for long periods, and to seek medical attention.

While Legionnaires’ cases are rare, the Napa outbreak is a reminder that the bacteria causing the disease are common in nature and can be found in man-made water systems, Relucio said earlier Wednesday.

"This means it’s very important for owners and managers of water systems that can create aerosols to take steps to prevent Legionella from growing and spreading in water systems,” she said.

Strategies to prevent the growth of Legionella bacteria in the home include flushing faucets and shower heads that have not been recently used, as well as cleaning, disinfecting and maintain all devices that use water, such as humidifiers, respiratory therapy devices, shower head and faucet aerators, water heaters, and hot tubs.

“We understand that this information is concerning, and we’re working really hard to get the answers that we need to ensure community safety,” Relucio said of Napa County’s response to the outbreak.

The disease is named after the first reported outbreak, which occurred in 1976 at an American Legion convention in Philadelphia and resulted in about 180 illnesses and 29 deaths. Some 10,000 cases were reported in 2018, but the CDC says the actual number is probably 1.8 to 2.7 times higher because the disease is underdiagnosed.

With reports from The Associated Press and the San Francisco Chronicle. Register reporter Edward Booth contributed to this report.

You can reach Howard Yune at 530-763-2266 or


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Public Safety Reporter

Howard Yune covers public safety for the Napa Valley Register. He has been a reporter and photographer for the Register since 2011, and previously wrote for the Marysville Appeal-Democrat, Anaheim Bulletin and Coos Bay (Oregon) World.

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