A 16-year-old girl has died from Ebola in Sierra Leone, dealing a blow to optimism that the west African country has finally turned the page on the devastating epidemic.

The teenager died Sunday in the northern city of Makeni, the National Ebola Response Centre (NERC) said Monday, two weeks after the death of a 67-year-old food trader in a neighbouring district.

On August 24, President Ernest Bai Koroma led a festive ceremony celebrating the discharge of Sierra Leone's last known Ebola patient, from a Makeni hospital.

No new cases had been recorded in more than two weeks, allowing Sierra Leone to join neighbouring Liberia in the countdown to being declared Ebola-free, with Guinea the only country where people are still falling sick with the deadly haemorrhagic virus.

NERC said the new death was  "disappointing" but that response teams were well prepared to cope with such an event.

It said the two deaths were not linked.

The village in Kambia district where the 67-year-old woman worked as a food trader was placed under quarantine after which four further people were diagnosed with Ebola.

The last case was recorded in the province nearly six months ago, World Health Organization (WHO) officials said.

The WHO says a country can be declared Ebola-free 42 days after the last confirmed case has tested negative twice for the virus.

The girl had reported symptoms last Tuesday but was not hospitalised until Saturday, residents told AFP.

A local NERC spokesman said her parents, teacher and classmates were being monitored.

The west African outbreak of Ebola has killed some 11,300 people since first emerging in December 2013 in Guinea, with Liberia the hardest hit.