Ontario Plants Propagation near St. Thomas Ont. on May 29, 2020. (Bryan Bicknell/CTV London)

The London-Middlesex Health Unit reported one new case associated with Ontario Plants Propagation Limited Sunday.

"We believe this outbreak is highly contained to group of workers," says Dr. Alex Summers, Associate Medical Officer of Health for the Middlesex-London Health Unit (MLHU). 

"There have been very little interaction with the Middlesex-London and Elgin communities so we are very confident this will be contained."

The MLHU tested 60 people associated with the St. Thomas area greenhouse and Summers says he anticipated this would eventually happen based on what they have seen around the province when it comes to people living in a close environment. 

"As a public health department we try to very rapidly place people who are ill or could become ill into quarantine," adds Summers. 

"Since Monday when we identified the first case, all close contacts have been placed into quarantine. That's six days since the last possible exposure to someone who could be ill from this outbreak."

Summers says the possibility of false-negative tests do exist, and that's why they have placed everyone in quarantine regardless of whether their test comes back positive.