Legionella in Disneyland Emphasizes the Growing Difficulties of Legionnaires' Disease Prevention

Legionella, the bacteria that is responsible for causing Legionnaires’ respiratory disease, can be a dangerous and deadly problem to deal with. Exposure tends to happen when individuals inhale water mist that is contaminated with the bacterium. The interesting part of the disease is that Legionella is present in most water sources at low levels. Problems arise and result in outbreaks when levels of Legionella are higher and the organism can proliferate in water systems like water heaters, cooling towers, and other stagnant water sources. Outbreaks of Legionnaires’ disease can perplex even the strongest infectious disease outbreak investigators and force them to look in places they may not have originally considered. In fact, a recent outbreak of Legionnaires’ disease at Disneyland in Anaheim, California, shows that even the “happiest place on earth” isn’t immune to this virulent pathogen.

Following reports of 12 cases in Anaheim roughly 3 weeks ago, public health officials found that all the individuals had spent time in Anaheim and 9 had visited the Disneyland theme park prior to their symptoms. One individual was a park employee. According to Disneyland officials, following a review, 2 cooling towers within the New Orleans Square Train Stations section of the park were reported to have had elevated levels of Legionella. Disneyland officials responded to the high levels of Legionella and noted that “those towers were treated with chemicals that destroy the bacteria and are currently shut down.” Interestingly, Disneyland officials had detected the high levels a month before and took actions to disinfect the towers.

There are many factors that may attribute an outbreak, such as warming climates, a large aging population, and increased attention on the disease, which all lead to a better chance of infections being reported. The recent outbreak in Disneyland is a good reminder of the inherent challenges with disinfection efforts and continued vigilance that is needed to ward off this bacterial infection. It is also a reminder that outbreaks can happen anywhere there is a water source, even Disneyland, or other areas that somehow seem to be untouchable.

For example, the presence of Legionella in water has made experts rethink the potential for exposure through water births. Tub births have been found to be a source of infant exposure as the bacteria thrive in the warm water and infants, like so many affected by Legionnaires’, are immunocompromised/immune-naive. Another surprising route of exposure? Car washer fluid. Researchers have found that the water in car washer fluid can harbor the organism and that low levels of methanol fail to inhibit its growth. Perhaps most commonly, Legionella can cause problems in hospitals too, with outbreaks being associated with water treatment failures and plumbing issues.

Back in Anaheim, public health officials have alerted medical providers to consider Legionnaires’ disease for patients with appropriate symptoms as the incubation period is around 2 to 10 days. Although healthy individuals tend to fight off the bacteria when exposed, it can be deadly for those of advanced age or with medical conditions. The 12 people that were infected were between 52 and 94 and 1 individual has died.