116 Confirmed Cases in North Carolina’s Largest Recorded Legionnaires’ Disease Outbreak

Outbreak investigation centers on a fairgrounds in the state’s western foothills.

An electron microscope photo of Legionella pneumophila bacteria, the species that causes most Legionnaires’ disease cases. Photo via Janice Haney Carr/Centers for Disease Control and Prevention

By Brett Walton, Circle of Blue

North Carolina health officials, as of October 2, have confirmed 116 cases of Legionnaires’ disease and eight cases of Pontiac fever in an outbreak that has sickened people living in more than a dozen counties in the western half of the state and also in South Carolina. One person has died of Legionnaires’ disease.

The link between these cases, health department officials say, is that many of the people who contracted the pneumonia-like illness attended the Mountain State Fair, held in the town of Fletcher, from September 6 to 15. Fletcher is about 15 miles south of Asheville.

State epidemiologists are focusing their investigation into the source of the outbreak on the Western North Carolina Agricultural Center, the site of the annual fair.

Interviews with people who have been diagnosed with the illness indicate a pattern to the infections, according to Zach Moore, state epidemiologist. The majority of people said that they had been in the Davis Event Center, a space where vendors showcase goods for sale. Most infected people had walked by hot tubs that were on display during the later half of the fair. There were two hot tub vendors at the event center, Moore said. The department is in contact with both vendors and has taken samples from one of them.

“Hot tubs definitely do produce aerosols and have been linked in other outbreaks,” Moore said. “Our early information suggests a link,” but the department is still awaiting data from additional testing. Samples from the hot tubs might be inconclusive if the hot tubs have been drained and disinfected in the days since they were on display, Moore said.

The only water sample from the Davis Event Center that has tested positive for Legionella bacteria so far was taken from a faucet in the women’s bathroom. The faucet itself is probably not the cause of the outbreak because it would not generate enough mist to spread the bacteria, Moore said. More men than women have been diagnosed with the illness.

“These findings suggest some some low level of Legionella that was present [in the building] that was able to grow in hot tubs or other sources in the Davis Event Center,” Moore told reporters. Moore cautioned that these are preliminary findings and the investigation is ongoing.

Legionnaires’ disease is contracted by inhaling water droplets that are contaminated with Legionella, the bacteria that cause the illness. The bacteria are present in the natural environment but they flourish in warm, stagnant water found in building plumbing systems. The disease is not spread person-to-person. Symptoms, which appear two to 14 days after exposure, include coughing, fever, and shortness of breath. Pontiac fever is a related but less virulent illness.

The outbreak is the largest on record in the state, according to Kelly Haight, a North Carolina Department of Health and Human Services spokesperson.

Legionnaires’ disease most commonly affects people older than 50, smokers, and those with weakened immune systems. The North Carolina outbreak fits this pattern. Though people who were infected range in age from 24 to 91, the median age of people confirmed to have the disease is 61. Nearly two-thirds of the victims in this outbreak have been hospitalized.

One of the largest Legionnaires’ outbreaks nationally in recent years, the North Carolina incident is the second record-setting event this year in a southeastern state. An outbreak in Atlanta in July that was traced to the cooling towers and water distribution system at the Sheraton Atlanta Hotel was the largest in Georgia’s history. There were 14 confirmed cases and 67 probable cases, with one death.

The number of reported Legionnaires’ disease cases in the United States has soared in the last two decades, increasing by a factor of five to around 7,000 per year. The true number may be even higher. An expert committee convened by the National Academies of Sciences, Engineering, and Medicine estimates that there may be as many as 52,000 to 70,000 cases annually when accounting for illnesses that are not properly diagnosed.

Experts attribute the rise in cases to various factors: more awareness among doctors to test for the disease, an aging population, aging water pipes, a warming climate, and water and energy conservation measures within buildings that result in water temperatures in plumbing that are ideal for bacterial growth.

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