State fairs are a mixed bag in the best of times. But for a hundred or so people who attended the North Carolina Mountain State Fair this past September, it was a nightmare. State health officials have traced an outbreak of Legionnaires’ disease to the fair, with the most likely source of infection being contaminated hot tubs.
The fair ran from September 6 to 15. Since then, according to the latest October 3 update from the North Carolina Department of Health, at least 128 people in the state who either attended or worked at the fair have gotten sick with Legionella bacteria.
When Legionella bacteria cause a serious lung infection, or pneumonia, it’s known as Legionnaires’ disease. Even with antibiotic treatment, this form of the disease can lead to lung failure, and around 10 percent of people diagnosed ultimately die. But more often, these infections end up causing a milder, flu-like illness called Pontiac fever. Unfortunately, the majority of cases in this outbreak (over 90 percent) are the Legionnaires’ kind. Eighty-one people so far have been hospitalized, and at least one person has died.
Legionella tend to thrive in freshwater. But natural environmental sources typically don’t expose us to enough of the bacteria to get sick. So what drives these outbreaks are sources of water where the bacteria is heavily concentrated and then easily dispersed through the air. Faulty plumbing systems, contaminated air conditioning units, and yes, hot tubs, are a common culprit behind Legionnaires’.
Health officials said Thursday that many victims had visited or worked near an event center at the fair, and they were much more likely to have walked by a hot tub display. Environmental testing identified the bacteria in a water sample at the location. But there are still questions about how the outbreak became so widespread.
“Finding Legionella in one water sample is an important piece of the puzzle, but it does not tell us how so many people were exposed at this event,” said Zack Moore, an epidemiologist with the NC health department, in a statement released Thursday. “To get Legionnaires’ disease or Pontiac fever, you have to breathe in Legionella in aerosolized water, meaning small droplets like mists or vapors.”
Right now, the hot tubs are the primary suspect, but it’s still possible there might have been other sources of contaminated aerosolized water. It’s also possible that the sickness tally will continue to grow, as more people who attended the fair and became sick are found. But the present danger seems to have passed, as health officials haven’t found any potential sources of infection since the fair ended. Still, the state is being cautious.
In a statement by the North Carolina Department of Agriculture and Consumer Services on Thursday, they announced that rentals of the event center would be suspended for the time being, while they “review and implement mitigation plans for the facility.”
Nationally, annual documented cases of Legionnaires’ and Pontiac fever have dramatically increased over time. There were five times as many cases reported—over 7,000—in 2017 than there were in 2000, according to the Centers for Disease Control and Prevention. But it’s unclear how much this uptick can be traced to “real” factors like more people being exposed to the bacteria or the bacteria becoming more virulent, as opposed to doctors and health departments simply getting better at finding cases. Most infamously as of late, an outbreak of Legionnaires’ sickened the townspeople of Flint, Michigan during 2014 and 2015 and killed nine, following an ill-conceived change to the water supply.
So far, according to national surveillance data, there have been over 5,300 reported cases of Legionella infection this year—slightly below the trend for 2018.