Legionellosis

Legionellosis is not spread from person to person. The bacteria that causes the infection lives in the environment in warm water. Less commonly, soil (such as potting soil) has also been implicated in cases of legionellosis. People become ill when they breathe in water droplets contaminated with these bacteria. Most cases are usually seen during the warmer months of the year.

Some common sources of Legionella are:

• Commercial cooling towers, heating, ventilation and air conditioning systems
• Large water systems in hotels (therefore travel is a common risk factor), hospitals and nursing homes 
• Hot tubs, whirlpools, and public spas
• Showers, especially those used outside the home or those that have not been in regular use
• Decorative water fountains
• Hot water tanks
• Humidifiers
• Creeks and ponds and the soil from their banks
• Potting soil and composting material used for gardening

Pontiac fever is a mild respiratory illness lasting about 1 to 3 days. Symptoms usually start within 1 to 2 days after contact with the bacteria and include a fever, headache, muscle aches and tiredness; less often there may be cough or nausea.

Legionnaires’ disease is a severe form of pneumonia which is sometimes fatal. Symptoms usually start within 5 to 6 days (can be from 2 to 10 days, and rarely as long as 3 weeks) after contact with the bacteria and include fever and chills, muscle aches, headache, cough, shortness of breath, weakness, diarrhea, loss of appetite and confusion. Delays in diagnosis may occur because symptoms are similar to other forms of pneumonia.

Typically, healthy people don’t become ill, or they develop the milder form of the disease. Those most at risk of developing life-threatening infections are adults over 65, persons who smoke or are heavy alcohol users, and those who have lung disease, kidney disease, weak immune systems, or diabetes.

Most cases of legionellosis presenting as Legionnaires’ disease are successfully treated with antibiotics. Persons with serious underlying health problems may take a long time to recover even after treatment. In rare cases, death can occur. Pontiac fever usually does not require antibiotic treatment. Treatment for legionellosis is the decision of a healthcare provider.

Generally, people can return to work and child care when they are fever free and feeling well enough to return. Since legionellosis is not spread from person to person, there is no risk of spreading the infection to others.

To prevent becoming ill with legionellosis or to prevent the growth of legionella bacteria:

• Follow manufacturers’ directions for regular maintenance and cleaning of all water devices such as hot tubs, whirlpools, humidifiers, air conditioners, fountains, etc.
• Keep your home water heater at a minimum of 60°C to help prevent the growth of Legionella. However, to reduce the risk of scalding, water at the tap should be no higher than 49°C. A qualified plumber can install mixing valves to control the tap water temperature.
• Avoid using tap water in respiratory therapy devices such as CPAP machines. Always follow the manufacturer’s directions for water use with these devices.
• Avoid smoking to decrease your own personal risk.
• Building managers should have water safety plans that include maintenance, monitoring, and cleaning of water systems.

If misting or spray devices are used, they should be properly installed, cleaned, and maintained. Legionella bacteria can grow in warm or stagnant water, especially where there is biofilm, sediment, or poor maintenance.

To reduce risk, misting or spray cooling devices should:

• Be plumbed and directly connected to a potable water source. For example, a municipal water supply.
• Not incorporate water recirculation holding tanks.
• Have lines flushed before use and after idle periods. Hoses and/or tubing must be kept out of direct sun where feasible (and/or consider using reflective materials to reduce heating).
• Follow manufacturers’ instructions for use (MIFU). MIFUs are to indicate how to clean, disinfect and maintain the equipment.
• Ensure components are clean and free of visible sediment, debris, and slime.

Visit Ottawa Public Health’s Extreme Heat and Humidity webpage for more information on how to protect yourself and help others during hot weather.

All cases of legionellosis must be reported to public health for follow up. Once a laboratory report of this illness is received, OPH interviews the individual, provides education and follows up with the person’s healthcare providers where appropriate. If a common source of illness is identified, OPH will provide follow-up investigation.