Sonoma County woman is first death in four cases of Legionnaire’s disease this year

Public health officials say a Sonoma County woman recently died of Legionnaire's disease, a severe form of pneumonia caused by exposure to Legionella bacteria.|

Sonoma County Public Health officials said Monday a Sonoma County resident recently died of Legionnaire's disease, a severe form of pneumonia caused by exposure to Legionella bacteria.

The case is the first reported death tied to Legionella exposure in Sonoma County this year, said Karen Holbrook, Sonoma County's deputy health officer. Holbrook said there have been three other local cases of Legionella exposure.

But none of the cases have involved a common source of exposure, which is the threshold for declaring a public health outbreak, she said.

“None appear to have common exposures, although we are in the process of investigating the most recent case,” Holbrook said.

The county disclosure came as Keysight Technologies announced that one of its employees died last week of Legionnaire's disease. Keysight officials said the employee could not have contracted the bacteria from Keysight facilities, because the work site was closed during the time the employee was likely exposed to Legionella bacteria. The Tubbs fire forced the closure of the Keysight campus from Oct. 9 to Nov. 7, said Keysight spokeswoman Marie Hattar.

Hattar said the employee, identified only as a female, showed up for work “already sick” after the campus reopened, indicating that the employee was exposed to the bacteria at a different location. Fellow employees advised her to go home, Hattar said.

Holbrook said that for reasons of privacy she could not say if the latest case of Legionnaire's disease reported to public health officials involved a Keysight employee. However, she did say public health investigators have ruled out the individual's workplace as the source of exposure.

Legionella bacteria has an incubation period of 2 to 10 days after exposure, she said. Symptoms include shortness of breath, cough, fever, fatigue and malaise, Holbrook said.

The county usually documents fewer than 10 cases of Legionella exposure during a single year. Last year, there were eight cases reported in the county.

“We do not have any local outbreaks in Sonoma County,” she said. “There is one outbreak in California that's tied to multiple cases in Disneyland and Orange County. There are outbreaks nationally, with one in Florida and one in New York.”

Holbrook said California usually has about 250 cases a year. Legionella bacteria can cause a severe type of pneumonia called Legionnaire's disease or a less severe respiratory illness called Pontiac fever.

Hattar said the employee's home burned down in the Tubbs fire and she subsequently stayed with family and, at one point, in an apartment building. But it's unclear where she might have been exposed to the bacteria. Keysight learned of the death the day before Thanksgiving and immediately contacted a physician who consults for the company. That doctor contacted the hospital where the employee was treated and learned that she likely had died of complications from Legionnaire's disease, Hattar said.

Hattar said that even though Keysight has been ruled out as the possible exposure location, the technology campus has undergone a complete cleaning and flushing of its water systems.

Holbrook said Legionnella bacteria is water-borne and naturally occurs in lakes and streams. People can go swimming in a stream or lake and be exposed, or it can even be in a lawn irrigation system, she said.

“Most common exposure is inhaling mist from a water source that has the bacteria,” Holbrook said, adding that county public health officials continue to investigate the possible source of the most recent case of Legionella bacteria.

You can reach Staff Writer Martin Espinoza at 707-521-5213 or

Editor's Note: A previous version of this article incorrectly stated there were four other local cases of Legionella exposure. There are only three other local cases, bringing the total to four.

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