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Five things to know about Legionella pneumonia — otherwise known as Legionnaires' disease

Legionnaires Disease
Francis Chandler
Centers for Disease Control and Prevention via AP
This 1978 electron microscope image made available by the Centers for Disease Control and Prevention shows Legionella pneumophila bacteria which are responsible for causing the pneumonic disease Legionnaires' disease.

Last month, San Diego State University (SDSU) announced a staff member had contracted Legionella pneumonia, otherwise known as Legionnaires' disease. This week, the campus confirmed professor Michael J. Buono had died from the disease.

But what is Legionnaires' disease? How does it spread? And should the community be concerned? KPBS reporters have been speaking with county experts to get answers.

How common is death from Legionnaires' disease?

"Legionnaires’ disease is an uncommon, reportable, treatable disease," said Dr. Cameron Kaiser, San Diego County Deputy Public Health Officer.

It is most dangerous to those with underlying conditions. Those who are immunocompromised are at the greatest risk of dying. About 10-25% of people will die from a case of Legionnaires’ disease, Kaiser said, but because the illness is so unusual and difficult to contract, generally, there are few deaths from the illness in the U.S.

According to the Centers for Disease Control and Prevention, health departments reported nearly 10,000 cases of Legionnaires’ disease in the U.S. in 2018.

What are the symptoms?

Symptoms include cough, fever, shortness of breath, muscle aches and headaches.

Risk factors include:

  • Age 50 years or older
  • Smoking (current or historical)
  • Chronic lung disease (such as emphysema or COPD)
  • Immune system disorders due to disease or medication
  • Systemic malignancy
  • Underlying illness such as diabetes, renal failure, or hepatic failure
  • Recent travel with an overnight stay outside of the home
  • Recent care at a health care facility
  • Exposure to hot tubs

Is this a new disease? Where did it come from?

Legionnaires' disease got its name from an outbreak at the 1976 Pennsylvania American Legion convention held at the Bellevue-Stratford Hotel in Philadelphia. The bacterium causing the disease grows in water, such as in storage tanks, rivers and air-conditioning ducts — making it a great way to infect a lot of people at once, Kaiser said.

Should the public or students at SDSU be worried?

Cases are uncommon nationally and in San Diego County. Even for people exposed to a known infected water source, most will never contract the illness, Kaiser said, and it is very rare for it to spread person-to-person. The public is encouraged to review SDSU’s plan.

Why has the building Buono taught at has been closed for more than a month?

After Buono contracted the disease, SDSU closed the Exercise and Nutritional Sciences (ENS) building, where he taught, for comprehensive testing, though it was uncertain if Buono caught the disease there. The building remains closed until testing is completed, which is expected next week.

The school is working with the county's Health & Human Services Agency to investigate how and where Buono contracted Legionella pneumonia.

For now, Kaiser advises the public to follow the university’s advice, stay out of the building and practice good hygiene. No additional cases have been reported for more than three weeks, which is a good sign, he said.