Pioneer Elder Care in St Catharines is the latest long-term care facility to report an outbreak of COVID-19 in Niagara region.
The home specializes in care for seniors suffering from dementia or Alzheimer's.
It was not clear if the case had been found in a staff member or resident.
Last week an outbreak was declared at Deer Park Villa in Grimsby.
A single case of COVID-19 was reported by the public health department on Wednesday after the daily case count went up by 7 on Tuesday in what the region's acting medical officer of health describes as an upward trend in daily cases during September.
There are currently four active outbreaks in the region, out of which two are in medical facilities, one at Eastdale Secondary School in Welland.
The location of the last outbreak has not been disclosed.
There are now 43 active cases in the region, of which most are in St Catharines.
1003 residents in the region have tested positive for COVID-19 since March 13.