To many gardeners, composting is one of the best things that can a person can do. By saving your old banana peels, vegetable rinds and used tea bags, you can reduce your carbon footprint on the Earth by returning essential nutrients, minerals and moisture to the soil and helping plants grow. However, recent research has reported that a bacteria found in potting soil and compost may be the cause of an emerging infectious disease called Legionnaire’s Disease.
Legionnaire’s Disease (Legionella) is a respiratory disease caused by a strain of bacteria of Legionella pneumophila. This bacterium thrives in freshwater environments such as lakes and streams and is also linked to a less severe flu-like disease known as Pontiac Fever. 95% of Legionella cases are caused by L. pneumophila; however the remaining 5% are caused by a similar bacterium known as Legionella longbeachae which was first identified from a patient in Long Beach, CA in 1980 (1). L. longbeachae is not found in aquatic environments and researchers are still unsure of its environmental reservoir; however, it was identified to be the major source of infection in potting soil.
Legionella is most commonly transmitted through horizontal means. It travels through water systems and the disease is contracted when humans inhale water droplets contaminated with the Legionella bacteria. For example, showering with water in which the bacterium has multiplied over time may increase your chances of getting Legionnaire’s Disease. L. longbeachae can be transmitted to the individual if the individual ingests or inhales the compost product containing this bacterium. Symptoms of this disease are similar to pneumonia and include cough, fever, headaches, muscles aches and shortness of breath. Older adults, regular smokers and individuals with chronic lung problems are most likely to be susceptible to Legionella.
The first case of Legionnaire’s Disease was an outbreak at a 1976 convention of the American Legion in Philadelphia (2). Since then, numerous cases of this disease have been identified. In fact, almost 6,000 cases of Legionella were identified in 2015. The most recent was at a health club in Orlando, FL a few days ago (3). Traces of the disease causing bacteria were found in the water at the LA Fitness gym and other facilities are being tested now following the infection of two of the gym’s members.
Legionnaire’s Disease is not harmful and has no definitive cure or vaccine but steps can be taken to prevent contamination and transmission of the disease. The CDC asks that all water systems should be checked and chemical levels maintained, especially units that use warm water, such as hot tubs, heaters, and large plumbing systems. Individuals are recommended to wash their hands immediately after handling compost products and to avoid breathing in the potting soil when gardening by opening the bags away from your face (4). By doing this, a person can minimize the risk of contracting Legionnaire’s Disease and can maintain good overall health and hygiene.
Update: Since writing this article, two more cases of Legionnaire’s Disease have been identified. Three individuals staying at the infamous Graceland Hotel contracted the disease on Thursday and two inmates at the Franklin Medical Center prison hospital were just recently diagnosed Friday morning.