As businesses and schools begin to open up after months of shutdown due to the COVID-19 pandemic, experts are warning that additional hazards could be waiting for returning occupants. One of those hazards can happen when building water systems are not maintained, causing stagnant water in the piping to occur. The reason for concern? Legionella.
Bicentennial Beginnings
In the summer of 1976, the nation swelled with pride and patriotism. It was our bicentennial. In Philadelphia, not far from Independence Hall – where our founding fathers signed the Declaration of Independence – 4,000 American Legion members descended on the Bellevue-Stratford Hotel to hold their annual convention. While the city sweltered, the legionnaires were enjoying the luxurious air-conditioned hotel, not knowing that something sinister lurked in the air. Ultimately 34 people died and over 200 people became seriously ill due to a then unknown assailant. Victims included not only convention-goers, but people who worked around or near the hotel.
In response to the unfolding medical emergency mystery, the Centers for Disease Control and Prevention (CDC) launched the largest investigation in its history at the time. No stone was left unturned. Everything from the hotel’s ice machines and kitchens, to plumbing, air-conditioning systems, and even toothpicks were examined. All possible causes were considered, ranging from food-poisoning to terrorism by anti-veteran war protestors. It wasn’t until six months later that the CDC announced that they had solved the case, and revealed the culprit – a new family of pathogenic bacteria they named Legionellaceae, with the prime offending member being Legionella pneumophila. In retrospective analysis, this “new” family of bacteria was found in clinical specimens as far back as 1943. Several unsolved epidemics of acute respiratory disease – including another event that killed three people at the very same hotel two years earlier – are now attributed to Legionella.
Legionella in Man-Made Water Systems
The genus Legionella is composed of over 50 species of bacteria, with over 70 identified serogroups. About half of the isolated species are thought to cause disease, ranging from the mild flu-like Pontiac fever, to the severe pneumonia of Legionnaires’ disease. Legionella pneumophila, the species that causes most Legionnaires’ disease, is thought to be responsible for up to 90% of disease caused by the genus Legionella.
Legionella is ubiquitous in nature and can be found in freshwater ponds, lakes and streams, as well as soil. In the environment, they are typically found as parasites of free-living protozoa. Infection risk increases when Legionella finds its way into man-made water systems, including plumbing, hot tubs, cooling towers, potable water systems, and fountains, and has a chance to multiply. The risk is greatest in stagnant systems with diminished disinfectant levels in the water. Infection can occur when contaminated water droplets are inhaled or aspirated into the lung. In the 1976 Bellevue-Stratford hotel incident, investigators believe the powerful fans on the roof-top air-conditioning system created a bacterially contaminated mist that fell on pedestrians below, and also entered the hotel lobby via a ground floor vent.
Most people exposed will not develop symptoms. Risks factors for infection include older age, smoking, a suppressed immune system, and chronic lung disease. Symptoms can include fever, chills, headache, shortness of breath, cough, muscle aches, chest pain, fatigue, and loss of appetite. Progression to bacterial pneumonia carries a mortality rate of approximately 10%, with some estimates as high as 30%. Early diagnosis and antibiotic treatment can significantly decrease mortality.
Legionella Cases on the Rise
The CDC reports that the number of cases has been on the rise since 2000, with nearly 10,000 cases reported in 2018. Since pneumonia caused by Legionella is clinically indistinguishable from other pneumonias, some experts believe that many cases go undiagnosed, and that the actual annual infection rate is much higher. A 2019 report by the National Academies of Sciences, Engineering, and Medicine estimated that the true number of cases is closer to 50,000 to 70,000 each year, and that Legionella infects and kills more people in the U.S than any other reported waterborne disease.
While cases of Legionella infection have been on the rise, health officials also worry that the current pandemic could cause a spike in cases. The standing water in a plumbing system of an unoccupied building, and the associated lower levels of residual disinfectant, such as chlorine, provide the perfect breeding ground for Legionella.
This past summer, the Sonoma Index-Tribune published a report about the discovery of Legionella in the water system of a major resort in California that occurred during the county’s shelter-in-place order. Fortunately, the resort’s water system was treated and re-tested before it reopened to the public. Even the CDC itself was not immune to this threat, and in August was forced to close several buildings it leases in Atlanta after Legionella was detected in water systems.
The CDC does provide guidelines and recommendations on reopening closed/unoccupied buildings, and information on how to prevent the spread of Legionella here: https://www.cdc.gov/coronavirus/2019-ncov/php/building-water-system.html ,and here: https://www.cdc.gov/legionella/wmp/index.html
Environmental Testing for Legionella
There are two testing methods used to detect Legionella in the environment: Culture method and polymerase chain reaction (PCR).
The culture method is the “gold standard” for Legionella detection. Samples collected in the field are sent to a laboratory for culture. Presumptive identification for Legionella is made by growth of organisms on selective culture media. Additional testing, such as direct fluorescent antibody (DFA) testing, is used for confirmation and speciation, and differentiates those species of Legionella, such as L. pneumophila, from those species not expected to cause disease.
PCR testing is a widely used analysis method that rapidly makes millions to billions of copies of a specific DNA sample. The method amplifies the DNA in the sample to a large enough amount to allow its study in detail. As PCR detects an organism’s DNA, the method is unable to differentiate between living organisms (that are capable of causing disease) and those that are not viable, and is not able to determine the specific species of Legionella detected, or its pathogenicity. False positive and false negative results, although rare, can occur. PCR analysis is also considerably more expensive than the culture method. However, its advantage is that it can return results in a matter of hours, compared to the 14 days required for culture results.
Gold Health and Safety Sampling/Testing for Legionella
GHSC has years of experience testing/sampling for Legionella. In the past, we performed testing in residences where occupants (tenants) were diagnosed with Legionnaire’s disease and the involved parties (tenants, landlord, or attorney) wanted to know if the property was the source of the problem. More recently, we have conducted testing for schools planning to reopen after months of closure due to the pandemic. In some cases, we have found the presence of Legionella and have worked with clients to correct the contamination. Both culture and PCR methods are available to clients.
If you have concerns about Legionella and would like to discuss sampling and/or testing options, please give us a call!
