Legionella (Legionnaires Disease)

Environmental Services Group is a Toronto based consulting company that provides sampling for the bacterial testing of Legionella in all types of properties including hospitals, nursing homes and critical properties.

In order to meet the needs of Infection Control, Public Health, Medical and Water Treatment professionals, Environmental Services Group uses sampling techniques such as DNA based Polymerase Chain Reaction (PCR) and 4 levels of culture based analysis. The PCR method provides critical, 24-48 hour results to assist our clients during a community or hospital acquired outbreak. The culture methods range from a presence/absence test to a heat enrichment test with identification of the Legionella species associated with outbreaks plus serotyping for Legionella pneumophila.

What is Legionnaires' disease?

The name "Legionnaires' disease" was coined in 1976 after a respiratory disease affected many delegates attending a convention in Philadelphia held by the American Legion of Pennsylvania. Eventually, the bacteria that was responsible for the disease was isolated and named as Legionella pneumophilia.

Two distinct illnesses, Legionnaires' disease and Pontiac fever, have been associated with the Legionella species. Legionnaires' disease is a severe pneumonia. Pontiac fever is a mild, non-pneumonia influenza-like illness. It is not clear why the same causal agent can produce two distinct illnesses.

In this document, we refer only to Legionnaires' disease; Pontiac fever is apparently uncommon; only a few outbreaks have been reported in the world. One of them, a large one, was in Canada.

What is the cause of Legionnaires' disease?

The bacterium responsible for Legionnaires' disease belongs to the genus Legionella. There are approximately 35 Legionella species known to produce the disease. Legionella species are commonly found in any aquatic environment. They can survive for several months in a wet environment and multiply in the presence of algae and organic matter. They can be found in groundwater, fresh and marine surface waters, and in potable (treated) water. They are protected against standard disinfection techniques used by city treatment plants.

What are the signs and symptoms of Legionnaires' disease?

Legionnaires' disease usually begins with a headache, pain in the muscles and a general feeling of un-wellness. These symptoms are followed by high fever (up to 40°-40.5°C or about 104°-105°F) and shaking chills. Nausea, vomiting, and diarrhea may occur. On the second or third day, dry coughing begins and chest pain might occur. Difficulty with breathing is often reported. Most patients develop pneumonia, a condition in which some of the lungs' air sacs fill with fluid or pus, so air is excluded. The pneumonia might involve both lungs and become so severe that hospitalization is required. Pneumonia resulting from Legionnaires' disease is similar to pneumonia from other causes. Laboratory tests are necessary for a confident diagnosis.

Mental changes, such as confusion, disorientation, hallucination and loss of memory, can occur to an extent that seems out of proportion to the seriousness of fever. Complete recovery can take several weeks. About 5-15% of known cases of Legionnaires' disease have been fatal.

How is Legionnaires' disease transmitted?

The transmission of Legionnaires' disease is not completely understood. The normal presence of Legionella in such environmental sites as water and soil is not automatically associated with an outbreak of the disease. It appears that the Legionella microbe, in order to produce the disease, must reach the lungs. Inhalation of small particles of contaminated water (aerosols) or soil seems to be the key. New evidence suggests that aspiration is another way that the Legionella microbes enter into the lungs to cause the disease. Aspiration means choking during drinking, ingesting or swallowing. This allows fluids and particles to mistakenly enter the lungs instead of going into the stomach.

How can we prevent Legionnaire's disease?

The likelihood of Legionella infection can be best reduced by good engineering practices in the operation and maintenance of air and water handling systems. Cooling towers and evaporative condensers should be inspected and thoroughly cleaned at least once a year. Corroded parts, such as drift eliminators, should be replaced. Algae and accumulated scale should be removed. These measures will not only control the growth of germs, but will also maintain operating efficiency at its peak values.

Sampling

We collect a water sample from wherever the possibility of the disease may be present. This includes the littoral zone or from cooling towers, condenser coils, storage tanks, showers, water taps, etc. In most instances, a 1 liter water sample is sufficient. The samples are sent to a laboratory promptly and we will know of the results in a timely manner. The count of bacterial is measured per 1ml of water, below is a chart dictating the counts of bacteria, and the appropriate actions.