Last Sunday, Alex Forrest of the firefighters union said both firefighters and paramedics arrived at a Winnipeg home to treat someone complaining of being short of breath.

Upon arrival, they learned the patient also had flu-like symptoms, an Ebola identifier, especially when combined with travel history of visitors at the location.

"That person had visitors from one of the African-identified countries, so the firefighters had to be held until the doctor at the time gave an all-clear that there was no chance of Ebola," said Forrest.

Because Sunday’s caller didn't identify flu-like symptoms, the call in question slipped through the 911 screening system set up two weeks ago.

"Any calls with positive indicators mobilize a specialized response of specially trained paramedics and a medical supervisor," said Chief John Lane of the Winnipeg Fire Paramedic Service.

If the call had been flagged, paramedics would have donned the exact same personal protective equipment staff at Health Sciences Centre demonstrated earlier this week, something that has happened four times since call screening began.

"In all four of those calls, Ebola was ruled out after further assessments by the medical supervisor and paramedics in consultation with infectious disease specialists," said Lane.

WFPS says over 30 per cent of 911 medical calls feature flu-like symptoms and trigger the advanced Ebola questioning.

The union representing firefighters and paramedics says communication about Ebola procedures has improved since last week. At that time, the union went public with member concerns about not knowing how to handle possible cases.

- with a report from Ben Miljure