Legionnaire’s disease is back in the news, this time with an outbreak apparently linked to Disneyland. Twelve infected people, age 52-94 have been identified—1 employee, 8 visitors, and 3 who had not visited the park but had been in Anaheim. One person died. Further cases are unlikely, as we are beyond the 2-10 day incubation period for the disease, and if cases occurred in visitors who became ill after returning home, the clue to exposure might well have been missed.
Two cooling towers were the likely source, having been found to have high levels of Legionella bacteria; they were shut down and were disinfected. The towers were located near the New Orleans Square TrainStation, but were more than 100 feet from areas accessible to the public. However, the 1976 Philadelphia outbreak showed that contaminated aerosols can spread for considerable distances.
Background on Legionnaire’s
The Disneyland outbreak is likely linked to cooling towers. They are commonly the culprit, as they were in the Bronx outbreak in 2015. Bacteria hiding in cooling towers also explains why outbreaks are more commonly seen in summer months. Hot tubs are another common source. Legionella is not spread person-to-person.
Each year approximately 8,000-18,000 people are hospitalized by this infection in the U.S. Most are aged 50 or older and many are current or former smokers and have chronic lung disease. Others are immunosuppressed from medications, cancer, diabetes, chronic renal disease, or similar. The infection can be fatal in ~10% of cases
Symptoms are similar to those with other pneumonia, except that sometimes headaches and diarrhea are prominent.
Although the infection is rare—our community hospital saw only ~1 patient per year—treatment guidelines for pneumonia recommend empiric coverage for “atypical” organisms with azithromycin (Zithromax) or levofloxacin (Levaquin), likely because of the high death rate.
This being Antibiotic Awareness Week, a global partnership to educate about antibiotic resistance and proper antibiotic use, I cannot leave unmentioned that I believe treating everyone for atypical bacteria (especially with Levaquin) is overkill and carries many downsides including breeding resistance, causing superinfection with C. difficile colitis, and causing confusion and psychiatric side effects in too many people.
Empiric (over-)treatment is driven by two things—lack of timely diagnostic tests and fear of deviating from practice guidelines.
Legionnaire’s Disease in Flint, Michigan
For those who may not remember the travesty in Flint, in an ill-thought out attempt at cost savings, Flint’s state-appointed emergency manager changed the city’s supply from Detroit’s Lake Huron water, treated with anti-corrosives, to water from Flint River. To save $100/day, they did not add anti-corrosives to the Flint system. This was in April, 2014, and it’s been a disaster for the community since then.
A series of misadventures cascaded, including an E. coli boil advisory, release of total trihalomethanes or TTHM (which are carcinogens), and markedly increased levels of lead in water. At that time, the projected “economic losses attributable to lead exposure in the 2009 cohort of 5 year-olds ranges from $3.19 billion (using U.S. blood lead levels) to $4.85 billion (using Michigan blood lead levels) per year in loss of future lifetime earnings.”
The heroes of the team uncovering Governor Snyder’s coverup included Dr. Mona Hanna-Attisha (Hurley Children’s Hospital, Michigan State University), Dr. Marc Edwards (Virginia Tech Engineering Professor and water quality expert), Curt Guyette (ACLU investigative reporter), NBC News, citizen scientists, and numerous Freedom of Information Act (FOIA) requests.
Despite their hard work and evidence, the city was long left at the mercies of volunteers and donations to have any clean water, as the state’s response was shamefully inadequate.
The blame game: Dr. Eden Wells, chief medical executive with the Michigan Department of Health and Human Services, has been charged with involuntary manslaughter over the debacle. During a hearing over her charges, local county health department officials say they received inadequate help from the state and that they lacked the expertise and staff to respond. The trial is still ongoing.
Ultimately, in 2014-15, 91 cases of Legionnaries’ were reported in Flint’s outbreak, with at least 12 deaths. (Dr. Marcus Zervos, head of Infectious Diseases at Henry Ford Hospital, felt that more deaths were attributable to the river water.) While the MDHHS attributed deaths to contaminated water at McClaren Hospital, a subsequent genetic analysis by Drs. Amy Pruden, Marc Edwards, and the Virginia Tech water study team suggested that the problem was more widespread throughout Flint’s water. Her study also found Flint tap water to contain Legionella levels up to 1,000 times higher than expected. The Virginia Tech study concluded that use of the Flint River for drinking water was “a likely trigger contributing to the increase in Legionnaires’ disease incidence“ there.
How does this happen? Their study explained that the corrosion causes iron to be leached from old iron pipes. The iron, a micronutrient, stimulates Legionella growth. Iron also inactivates the chlorine disinfectant. Each of these leads to growth of Legionella. Studies of public water corroborated this, finding high levels of Legionella and iron in water from the Flint River, and undetectable chlorine, but no Legionella in buildings supplied with Detroit’s water, which is from Lake Huron.
Per an MLive report,
“Public health officials identified the Flint River as a potential source of the city’s Legionnaires’ outbreak as early as 2014, but city, county, state and federal officials never told the public until more than a year later.”
Now, years after the contaminated water crisis in Flint, the water is improving, according to Edwards. The water now meets the U.S. Environmental Protection Agency’s (EPA) Lead and Copper Rule. Levels of Legionella and other pathogens, as Shigella, are down to pre-outbreak levels, as well. Yet residents are still advised to use filters or bottled water to reduce their lead exposure.
Lessons from Disneyland, Flint, and other outbreaks
Water cooling towers need to be regularly tested and disinfected against Legionella bacteria.
We will likely see more outbreaks, given our aging infrastructure across the U.S., with many cities failing to address corrosion in their aging water pipes, and other cities assuming austerity budgets. Our aging population and having many more immunosuppressed people are likely factors as well.
An outbreak at NIH suggests we be wary of fashionable water features, especially in hospitals or around immunocompromised people. Similarly, Legionnaire’s has caused outbreaks linked to a grocery store mist machine and shower heads, and to improperly cleaned respiratory therapy equipment.
The take-home? Cleaning and maintaining adequate chlorination will markedly reduce your personal risk of illness. Invest more in infrastructure repairs. Support Infectious Disease practitioners, epidemiologists, and public health. Coverups don’t work when citizens and scientists band together; government and hospitals should stop trying to hide problems from the public.