Middlesex-London Health Unit is providing an update to the community one week following the declaration of an outbreak of Legionnaires’ Disease.

To date, 22 cases are attached to the outbreak and 6 cases are currently hospitalized. All identified cases were hospitalized at some point over the course of their illness. There has been 1 fatality. Most of the cases live and/or work in a 5 km radius of one another in the southeast side of the City.

Legionnaires disease is a respiratory illness caused by a bacteria called Legionella. It is characterized by high fever, chills, a dry cough, shortness of breath and can lead to pneumonia. Symptoms of Legionnaires usually begin two to ten days after encountering the bacteria.

Legionella bacteria are found naturally in the environment, usually in water (hot tubs, cooling towers, hot water tanks, large plumbing systems or parts of an air-conditioning system). If the bacteria are then aerosolized or misted into the air (via wind or fans), humans may breathe them in and become unwell. Most people exposed to Legionella do not become ill. Some may experience a milder illness called Pontiac’s disease, which is resolves itself. Individuals who are older, have lung problems or are immune compromised are at greater risk for serious infection.

Legionella is not transmitted from person-to-person, through public waterworks, or through the consumption of contaminated foods.

Middlesex-London Health Unit is working closely with Public Health Ontario and the Public Health Ontario Labs to identify the source of the outbreak so that it can be remediated. With many cooling towers and other types of cooling equipment in a region of this size, it will be a lengthy investigation. When Legionella bacteria is found, the DNA of that sample is compared to the DNA of the samples from those who are sick. This is the only way to know if the exact source of the outbreak has been located. It may take weeks before the source is identified and confirmed as the cause of the outbreak. Sometimes in investigations like this one the source of the bacteria is never definitively found, though the outbreak may naturally end.

We do not recommend any changes in behaviour or activities for individuals. If anyone develops symptoms (fever, cough, shortness of breath), they are encouraged to seek medical attention as needed.

In the meantime, Middlesex-London Health Unit asks all business owners and property managers to ensure that all cooling equipment is regularly maintained and sanitized as per the manufacturer’s instructions. This is the best way to reduce the risk of further legionella outbreaks.