Source of legionnaires' disease outbreak that sent 6 to hospital may not be revealed

Two legionnaires' disease outbreak patients in the Moncton region remain in hospital, one of them in intensive care, as the Public Health investigation into the source continues, the regional medical officer of health announced Monday.

But even if the source of the seven confirmed cases is identified, it's unclear whether it will be made public.

"It's premature for me at this point in time to confirm whether or not we will release that information publicly," Dr. Yves Léger told reporters during an afternoon news conference.

During a 2019 outbreak when 16 people became ill, the province refused to release where the outbreak originated. CBC News filed several right-to-information requests and in December 2020, documents revealed cooling towers atop Organigram's cannabis production plant in western Moncton were the source.

"Certainly, there were a lot of lessons learned in 2019 that we still keep with us and will be part of those considerations when we get to that point," said Léger. "But at this point in time, it's too early to confirm whether or not that that information will be released."

Public Health is awaiting the results of patient samples cultured and sent to the Quebec Public Health lab to determine if the bacteria in all the cases is the same, which would confirm whether there is one source of infection or more, he said.

Those results are expected this week, but Léger said a contaminated cooling tower is the the most likely cause.

"To date we haven't been able to find any commonalities or common links between our cases, except that they all reside or have travelled in the greater Moncton area during their incubation period or during the time at which they could have been exposed.

"This leads us to believe that a contaminated cooling tower is the most likely cause of their infection."

The pneumonia-like illness is caused by legionella bacteria. It can be found in natural waterways, such as ponds and lakes, as well as human-made systems such as air conditioners, cooling towers, spas and decorative fountains.

The illness can be contracted by inhaling water droplets containing the bacteria.

Public Health announced the latest outbreak earlier this month. At that time, six cases had been confirmed within two weeks.

The breakdown of the seven cases now reported include three men and four women. One is in their mid-20s, the rest are between their 50s and 90s.

All but one had to be hospitalized, but only two remain in hospital, Léger said.

2 western cooling towers disinfected

While Public Health awaits the typing results, it has focused its efforts on trying to identify the possible contaminated cooling tower, he said.

"Looking at our cases' travel patterns coupled with wind patterns in the greater Moncton area during their time of exposure has led us to focus our initial efforts towards the western part of the city.

"This area is similar to the one targeted in 2019. However, it is larger as well."

Using the list of cooling towers collected from the 2019 outbreak, as well as input from city staff, Public Health identified 11 sites that required sampling, said Léger. A total of 23 cooling towers were tested.

Nine of the cooling towers showed the presence of some levels of legionella bacteria, but most were at very low levels, he said. Two cooling towers had legionella bacteria at levels which required cleaning and disinfection.

Asked how high the levels were, Léger said they were "not to the extent that we would have found our smoking gun, for example, or needed an immediate shut down."

Léger did not reveal the location of these two towers or say whether they were involved in the 2019 outbreak.

"These results do not confirm the source of our outbreak as we expect to find some legionella bacteria in some of the cooling towers sampled," he said. "We still need to wait for bacteria grown on culture and conduct typing, to see if these are exactly the same bacteria as the ones in our patients."

Those results could be available next week, he said.

Northeastern, downtown towers being tested

In the meantime, Public Health will continue to test cooling towers in other parts of the city, including seven in the northeastern area, largely defined by the Caledonia Industrial Park, and roughly 11 in the downtown core.

"We know that [the bacteria] can be picked up by prevailing winds and carried for many kilometers away. So we're not necessarily looking at a specific location in close proximity" to the infected people, said Léger.

Contaminated towers in these areas is "possible," he said, "albeit less likely."

Sampling of these sites started Monday and should finish by the end of the week.

Public Health found out about the first case in the latest outbreak on July 27. The first symptoms were experienced on July 21.

Some of the patients required intensive care and were "quite, quite ill," Léger had said.

People who become ill with pneumonia-like or respiratory symptoms, such as fever, chills, cough, shortness of breath, muscle aches and headache, are urged to seek medical care or call 811.

Legionnaires' disease can be fatal in about 10 to 15 per cent of cases.