The workers were shifted to the country's capital Freetown.
"This was the responsible thing to do. The field team has been going through a traumatic time after this incident," Xinhua quoted Daniel Kertesz, a WHO representative in Sierra Leone, as saying.
"They are exhausted from many weeks of heroic work, helping patients infected with Ebola. When you add a stressor like this, the risk of accidents increases," he added.
WHO Sunday said an international health worker deployed by WHO has contracted Ebola in Sierra Leone, marked the first time someone working under the aegis of WHO has fallen ill with the disease.
Once the investigation has been completed and appropriate actions have been taken, WHO will move a team back to Kailahun, the statement said.