MONTREAL -- An internal investigation is underway at a long-term care home (CHSLD) in Marieville, on Montreal's South Shore, after an outbreak of COVID-19 saw the deaths of 25 people. 

One manager has been suspended after what the regional health director called "troubling behaviour," though authorities aren't elaborating for now on what that means.

The outbreak at the Sainte-Croix care home is particularly troubling to many because the CHSLD avoided COVID-19 completely in the first wave.

Now, it's the province's hardest-hit such home, with 152 cases since Sept. 30.

It's unclear exactly what went wrong, say those at the CISSS Monteregie-Centre, but an internal investigation ordered on Oct. 13 is going to look into it.

"Our testing found a lot of cases in people who didn't have symptoms," said Richard Deschamps, the director of the CISSS.

Broken lab equipment also led to delays in processing tests, he said.

As for the suspended employee, that measure will remain in place for the duration of the investigation.

Quebec Health Minister Christian Dube said Thursday that the decision to suspend was up to the CISSS.

He also pointed out that the Monteregie had many COVID-19 outbreaks in the community this summer and that with that kind of circulation of the virus, it's difficult to keep it out of long-term care homes.

INVESTIGATION WILL TRACE OUTBREAK'S EVOLUTION

The CISSS said the virus was first brought into the facility when an employee came to work while unknowingly infected.

"The identification of the first positive cases among users results from a massive screening carried out on September 30, when a first employee had just tested positive and had worked without knowing he had the disease," reads a statement from the health district on Thursday.

"Further massive screenings were carried out over the following days. The situation evolved rapidly, both for residents and staff."

The CISSS said it put preventative measures in place since the detection of the first case, including increased staff, medical supplies and security measures; increased testing efforts; isolation measures; and employee uniforms, among others.

The cases are almost evenly split between residents and staff. Since the end of September, 79 residents and 73 staff members have tested positive for COVID-19. 

As of Thursday, the CISSS reported 37 active cases among residents and 31 among staff. 

"The absence of symptoms by staff or residents is contributing to the spread of infection. Several positive cases have been found among asymptomatic people during massive screenings," the CISSS said.

A union leader said that, despite the suspension of the employee, it's very unlikely that this kind of outbreak can be fairly blamed on one person. 

"Our health-care system was already fragile before the pandemic," said Denis Grondin of the nurses' union.

The first wave of COVID-19 hit CHSLDs hard across the province of Quebec, prompting multiple investigations that have uncovered existing issues within the health system.