A health worker wearing protective gear tends to a newly admitted suspected Ebola patient in a quarantine zone at a Red Cross facility in the town of Koidu, Kono district in Eastern Sierra Leone in this December 19, 2014 file photo. [Photo/Agencies]

FREETOWN - Sierra Leone has recorded two new cases of Ebola in Freetown in the past few days, disproving the assumption that the capital city had already defeated the deadly virus, officials said on Monday.

The worst known Ebola epidemic in history has killed more than 11,000 people in West Africa, about a third of them in Sierra Leone. Liberia became Ebola-free in May, but its neighbours Sierra Leone and Guinea are still struggling to get to zero cases despite hundreds of millions of dollars in aid.

"This is worrisome because we had already closed all Ebola quarantine structures in Freetown since we had gone for weeks without a case," said Sidi Yahya Tunis, a spokesman for the National Ebola Response Centre (NERC).

Tunis said there were concerns about further infection since the two cases were reported in Magazine, a densely populated slum lacking adequate hygiene facilities.

Health officials said the first case in Freetown since May 29 was a fisherman who caught the hemorrhagic fever from his girlfriend in the northern district of Port Loko.

Shortly afterwards, a family member who lived in the same household also caught the virus. The other six cases recorded in Sierra Leone over the past week were in the northern provinces of Port Loko and Kambia, health ministry data showed.