About a dozen people in the Anaheim, CA area, or visitors to the area in September were diagnosed with Legionnaires’ disease, according to Orange County health officials.

Legionella pneumophila bacteria/CDC
Legionella pneumophila bacteria/CDC

This follows a report in late October when eight cases were being investigated.

Of the 11 total that have been diagnosed with the bacterial infection, eight have a history of visiting Disneyland Parks prior to developing illness; three have no history of Disneyland exposure.

Case ages range from 52-94. Ten of the 11 ill were hospitalized, and one person died.

According to a LA Times report, Disney reported on Nov. 3 that routine testing had detected elevated levels of Legionella in two cooling towers a month earlier, and the towers had been disinfected. Disney took the towers out of service on Nov. 1, performed more testing and disinfection, and brought them back into service on Nov. 5.

Health officials are advising healthcare providers to consider Legionnaires’ disease in any patient who develops illness with pneumonia who lives in, works in or has traveled to Anaheim or Disneyland within 10 days of symptom onset

Legionellosis refers to illness caused by Legionella bacteria and usually results from exposure to contaminated water aerosols or from aspirating contaminated water.

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Legionella pneumophila is the most common cause of infection, and the majority of L. pneumophila infections are caused by serogroup 1.

Legionellosis presents in two distinct illness patterns:
  • Legionnaires’ disease is a progressive pneumonia with a 2-10 day incubation period. The disease can also cause cardiac, renal and gastrointestinal involvement.
  • Pontiac fever is a self-limited, influenza-like illness without pneumonia that has a 1-2 day incubation period caused by an inflammatory response to L. pneumophila-produced endotoxin.
Patients at particular risk include those who are:
  • Immunocompromised
  • Have chronic lung disease
  • 50 years of age or older

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