The retailer confirmed the case in a statement Wednesday afternoon.
A spokesperson said: “A member of the team at our Castle Douglas store exhibited mild symptoms of Covid-19 and acted very quickly and responsibly to self-isolate and was tested immediately.
“The team member had been away from the store for over a week previously, so we are confident that with our improved security measures we can ensure a safe shopping and working environment.
“We would like to thank the members of the team for their commitment and meticulous support in the implementation of these measures.
“We wish our team members a speedy recovery.”
An eight-point security plan has been in place since the start of the pandemic, the spokesperson said.
Measures include regular hand washing, hand sanitizing stations, protective screens, physical distancing, and signage.
Store commissioners and regular cleaning of high touchpoint areas such as baskets, trollies and checkout areas are also present.
All team members have supplies of face coverings or visors to wear in store.
The spokesperson added, “The health and safety of our team members and customers has been our number one priority since the start of the Covid-19 pandemic.
“We have remained open as a critical retailer throughout and have introduced extensive safeguards across all of our stores and across the company.”