Middlesex-London Health Unit staff have concluded the investigation into the cause of an outbreak of Legionnaires’ disease that made a half dozen people from a south central London neighbourhood ill. After investigating several potential sources, Public Health Inspectors received notification that samples they had taken from a cooling tower in the area were a genetic match for the bacteria which made six people sick. All those who had been diagnosed were hospitalized and are now recovering from their illness.

Last week, Health Unit staff notified the Middlesex-London Board of Health that it had declared a legionellosis, or Legionnaires’ disease, outbreak after being notified of 13 cases of the illness since July; six from the same area of south central London. The investigation and search for a cause were still active at the time, but laboratory reports received yesterday drew a conclusive link for the largest cluster of cases.

“The samples taken from a cooling tower were a match with samples we obtained from residents in the neighbourhood who became ill,” says Dr. Alex Summers, Associate Medical Officer of Health with the Middlesex-London Health Unit. “We have taken extensive measures to ensure that this equipment no longer poses a threat to human health.”

Legionnaires’ disease is a form of pneumonia caused by the Legionella bacteria. Symptoms usually begin within two to 10 days of being exposed to the bacteria and include cough, headaches, fever, muscle pains, shortness of breath and may also be accompanied by nausea and vomiting. The bacteria can also cause a milder, influenza-like sickness called Pontiac fever.

The Health Unit normally receives an average of six reports of Legionnaires’ disease in the London and Middlesex County region each year. So far, the agency has identified 15 cases in 2019, 13 of which have been reported since July.

Legionella bacteria can be found in damp and wet environments, including swimming pools, hot tubs, fountains, soil and most commonly, air conditioning cooling towers. When these bacteria are present in water or soil that has been aerosolized (converted to a fine spray), it can be inhaled by those who may be susceptible and may lead to Legionnaires’ disease.

While proper cleaning and maintenance of equipment is critical to limiting the potential for Legionella colonies to grow in equipment, there are no specific precautions that individuals can take to protect themselves. There is also no vaccine available for Legionnaires’ disease. For more information, please visit www.healthunit.com/legionnaires-disease.

Media Contact:
Dan Flaherty, Communications Manager, Middlesex-London Health Unit,
519-663-5317 ext. 2469 or 519-617-0570 (cell.)

Spokespeople:
Dr. Alex Summers, Associate Medical Officer of Health, Middlesex-London Health Unit