Nova Scotia·Q&A

Legionnaires' disease can thrive in old pipes, warns expert

An infectious disease specialist says people shouldn't be concerned about the risk of a widespread outbreak but under the right conditions bacterium that causes legionnaires' disease may thrive.

Infectious disease specialist says bacteria thrives in warm, stagnant water

Provincial officials say there are usually two or three cases of legionnaires' disease each year in Nova Scotia. (Janice Haney Carr/Centers for Disease Control/Associated Press)

The bacteria that causes legionnaire's disease may be lurking in old pipes or even decorative fountains, but an infectious disease specialist says the public should not be worried about a widespread outbreak.

Dr. Walter Schlech, who works at Dalhousie's department of medicine, says it is not uncommon to see individual cases as well as clusters of cases, but the disease is not contagious between people. 

The Nova Scotia Health Authority has confirmed three cases of legionnaire's disease at an apartment complex in Dartmouth.

A fifth case of legionnaires' disease is being investigated at an apartment building in Dartmouth. (Stephanie vanKampen/CBC)

The illness is contracted when people breath in water droplets contaminated with Legionalla bacteria. It's more common among older people and in 15 per cent of cases, it can be fatal.

Is hot weather contributing to this outbreak?

Dr. Schlech says hot weather itself isn't a problem but high temperatures often lead people to turning on air conditioners, which can be a source of the infection.

"If the water is warm in the cooling towers that are sometimes responsible for these outbreaks, then the growth of the organism may be enhanced during warm temperatures," he says.

How challenging is it to eradicate the Legionella bacteria?

It can be "quite difficult" says Dr. Schlech. Techniques include hyper chlorination and heating the water to high degrees may help get rid of the bacteria once it's established in a building. But he says older structures may pose particular challenges.

"The problem comes in that, particularly with old plumbing, there can be scale, old biofilms that may be present in the piper system which can harbour the organism and these are often very difficult to eradicate," he says.

Is the bacteria limited to old buildings?

No. Dr. Schlech says he once investigated an outbreak in St. Croix, the U.S. Virgin Islands. He discovered it was caused by vapour released from an ornamental fountain in a hotel courtyard.

He says the bacterium is found in the environment and can grow under the right conditions. He says it has been known to exist in the plumbing systems of hospitals.

"There are a number of potential places the organism can hide," he said.

The Public Health Agency of Canada says the bacteria may grow in stagnant water and warm water, including in whirlpool bathtubs, hot tubs, public spas and humidifiers. In people's homes, it may disperse from water heaters, faucets and shower heads.

The agency says people can reduce their risk by cleaning and maintaining mist-producing devices. It also recommends people keep home water heaters at a minimum of 60 C. It also cautions people to consult a plumber so that water isn't scalding hot when it comes out of the tap.

How is the disease diagnosed?

It can take a week or two to pinpoint the bacterium in a lab because an organism must be grown from a sample taken from people's lungs, says Dr. Schlech.

"It usually takes some epidemiological sleuthing," he says.

But that should not delay treating the problem. Dr. Schlech says the same antibiotics used to treat pneumonia are effective. He recommends people people go to a doctor if they have a severe respiratory issue.

Symptoms also include fever, chills and muscle aches. He says severe headaches and diarrhea can also tip doctors off to it being legionnaires' disease.

How widespread is it?

The Public Health Agency of Canada says there are usually fewer than 100 reported cases a year, but the agency suspects many more people who are treated for pneumonia have the disease and are not tested for it specifically.

Dr. Schlech recommends people avoid showering in buildings they suspect are contaminated. He also suggests people take medications with distilled water.


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