The lab and two additional agency scientists were deployed Saturday and join a Canadian team set up previously in the district of Kailahun in eastern Sierra Leone, near the borders of Guinea and Liberia, the Public Health Agency of Canada said.
A third scientist will leave on Tuesday.
The team already on the ground will continue to provide rapid diagnostic support to help local health-care workers, producing results within hours.
The second team will work with Médecins Sans Frontières (Doctors Without Borders) to monitor the effectiveness of infection prevention measures, such as hand-washing stations, face masks and disposal sites.
Canada has had a continuous laboratory presence in the West African outbreak zone since June, with three-person teams typically spending a month at a time in operation.
The team was abruptly withdrawn from Sierra Leone in late August when three people at the hotel complex where they were staying were diagnosed with Ebola. It is believed the infected people were hotel staff.
At the time, the Public Health Agency said the lab workers were being brought home for their own safety. The agency then sent a replacement team to Sierra Leone on Sept. 6, saying arrangements were made to ensure a safer living environment.
To date, Canada has contributed $35.4 million in support of humanitarian, security and public health interventions to address the spread of the Ebola virus in West Africa.
The Canadian government has also donated up to 1,000 doses of an experimental Ebola vaccine to the World Health Organization.
WHO has said about 3,400 people in West Africa have died of confirmed, suspected or probable cases of Ebola as of the end of September. A total of 7,178 cases have been reported, most of them in Guinea, Sierra Leone and Liberia.