Health officials in Sierra Leone have confirmed one new death from Ebola, only days after the last known patient was released from hospital.

According to AP, results from a test on the body of a 67-year-old woman from the country's northern Kambia district tested positive for the Ebola.

Following the discharge of the patient on Monday, health workers began a 42-day countdown before the World Health Organisation could declare Sierra Leone Ebola-free.

"We should not despair as we have been expecting this," said OB Sisay, Director of the National Ebola Response Center. "We need to stay focused and maintain our discipline." 

Last year's outbreak was the largest in history, and killed almost 4,000 people in Sierra Leone, and more than 11,300 worldwide - though the vast majority of deaths were in West Africa.