One case of Legionnaires’ disease has been diagnosed on the island of Oahu and is being investigated by the Queen’s Medical Center in Honolulu and the Hawaii State Department of Health (DOH), according to KHON2 TV.

Dr. Leslie Chu, chief medical officer at Queen’s Medical Center, confirmed that the patient is being treated there but did release the age or gender of the patient, or their current condition. Chu told KHON2 that the hospital is investigating potential sources of the disease.

Residents or visitors to Oahu exhibiting pneumonia- or flu-like symptoms (see the list of symptoms below) should seek immediate medical attention from their health-care provider.

Oahu is the third-largest of the 140 islands that make up the state of Hawaii (tourists visit only the six largest islands: Hawaii, Maui, Oahu, Kauai, Molokai, and Lanai). Oahu is home to the city of Honolulu, Waikiki Beach, Pearl Harbor, Diamond Head and the Polynesian Cultural Center, which are among the most popular destinations in the state.

Locating the source of the Legionella bacteria, which causes Legionnaires’ disease, is of extreme importance, because Legionnaires’ disease, which is a potentially fatal type of pneumonia, often presents in clusters or outbreaks. Being able to identify the cause of the patient’s illness could eliminate the threat for others.

Outbreak or cluster?
Clusters and outbreaks are where multiple cases are reported in or around the same proximity and within a designated period. Multiple illnesses reported within days or weeks, rather than months, are identified as an outbreak and occur in a more limited geographic area. When multiple diseases occur in the same general vicinity within a period of three to 12 months, a cluster is suspected.

Climate change

Legionnaires’ disease cases in Hawaii have increased each of the past two years (12 in 2016 and 14 in 2017), after a slight decrease in 2015 (7 cases), according to the DOH. Nine cases were reported in both 2013 and 2014.

The most recent Hawaiian outbreak occurred in June 2016, when two confirmed cases and a third suspected case forced the temporary closure of the WorldMark Kapaa Shore Resort in Kapaa, Kauai.

Legionnaires’ disease outbreaks have made headlines across the United States nearly annually since the disease was discovered in 1976. That was the year more than 200 attendees at an American Legion Convention in Philadelphia were sickened, and 34 of them died.

Legionnaires’ disease is “an emerging disease in the sense that the number of recorded cases of Legionnaires’ in the United States continues to increase,” said Laura Cooley, MD, MPH from the Respiratory Diseases Branch of the Centers for Disease Control and Prevention (CDC). Cooley said the increase is due to a rise in the susceptibility of the population, with more and more people on immunosuppressive medications.

In addition, there could be more Legionella in the environment, with warmer temperatures creating the right conditions for bacterial growth. The previous three years have been the hottest years on record, with NASA ranking 2016 as the warmest and 2017 second-warmest.

Legionnaires’ 101

Legionnaires’ disease – also called legionellosis and Legionella pneumonia – is a severe type of lung infection. According to the CDC, an estimated 25,000 cases of pneumonia due to Legionella bacteria (Legionella pneumophila) occur yearly in the U.S. Only 5,000 cases are reported, however, because of its nonspecific signs and symptoms.

Ten percent of people who become infected with Legionnaires’ disease will die from the infection.

Legionella bacteria are contracted by inhaling microscopic water droplets, usually in the form of mist or vapor. The bacteria, which grow best in warm water, are found primarily in human-made environments.

Where do Legionella live?
Outbreaks have been linked to a number of sources:

  • large plumbing systems
  • showers and faucets
  • hot-water tanks and heaters
  • swimming pools
  • hot tubs and whirlpools
  • decorative fountains
  • mist machines and hand-held sprayers
  • equipment used in physical therapy
  • water systems, such as those used in hospitals, nursing homes, and hotels
  • the cooling towers of air conditioning systems.

Legionnaires’ symptoms
Legionnaires’ disease is similar to other types of pneumonia. Symptoms can even resemble those of flu, which is why it often goes under-reported.

Symptoms include:

  • cough
  • shortness of breath
  • fever
  • muscle aches
  • headaches
  • gastrointestinal symptoms, such as nausea, vomiting, and diarrhea.

Who is most at risk?
Anyone can become ill from Legionella, but those most susceptible to infection include:

  • people 50 years of age or older
  • smokers, both current and former
  • heavy drinkers of alcoholic beverages
  • people with chronic lung disease
  • people with compromised immune systems
  • recipients of organ transplants
  • individuals who are on specific drug protocols (corticosteroids, to name one).