Kaiser Permanente Santa Clara confirms 18 Legionella infections

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Published  May 6, 2026 2:07pm PDT
KTVU FOX 2

Legionella (Photo By BSIP/UIG Via Getty Images)

The Brief

    • Kaiser Permanente Santa Clara confirmed the presence of Legionella bacteria, and said "several people" had been infected.
    • The bacteria develops in water, and cannot be transmitted from person-to-person.
    • The hospital has implemented additional water treatment measures, and will continue to treat patients while experts search out the source of the bacteria.

SANTA CLARA, Calif. - Experts at Kaiser Permanente Santa Clara are trying to locate the source of Legionella bacteria that has infected 18 people, the company recently announced.

The bacteria was first detected during a routine internal monitoring process, Kaiser Permanente announced in a press release. It is unclear if the infected individuals were patients, staff or visitors.

"Legionella bacteria occur naturally in water and are spread by inhaling contaminated mist, not through person-to-person contact," a release from the company states. "While we work to determine the source, out of an abundance of caution, we have implemented additional water treatment measures and have taken preventive measures to ensure the safety of all patients, employees, and visitors."

Legionella source

Dig deeper:

Kaiser Permanente Santa Clara is continuing to treat patients while experts try to trace the source of the bacteria.

Legionella bacteria occur naturally in lakes and rivers, as well as in human-made water systems, including shower heads, sink faucets, hot tubs, decorative fountains, and large, complex plumbing systems.

The California Department of Public Health states that small water droplets or mist from these sources can contain Legionella bacteria, which can infect people with Legionnaires’ disease, a pneumonia-like infection, or Pontiac fever, a milder illness.

At risk

What we know:

Legionellosis, the general name given to infections caused by the bacteria, cannot be transmitted from person-to-person. Most healthy people exposed to Legionella do not develop Legionnaires’ disease.

Those at higher risk include:

  • Adults over 50
  • Current and former smokers
  • People with certain health conditions including:Chronic lung disease (including COPD and emphysema)CancerDiabetesKidney or liver failureTreatment with medication that weakens the immune system (including chemotherapy and medicine taken after an organ transplant)
  • Chronic lung disease (including COPD and emphysema)
  • Cancer
  • Diabetes
  • Kidney or liver failure
  • Treatment with medication that weakens the immune system (including chemotherapy and medicine taken after an organ transplant)

Legionnaires’ disease can cause symptoms including:

  • Cough
  • Shortness of breath
  • Fever
  • Chills
  • Headaches
  • Muscle aches
  • Nausea
  • Vomiting
  • Diarrhea
  • Confusion

The Source: Kaiser Permanente Santa Clara

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