Four people remained in quarantine in Sierra Leone after 55 others were declared free of the Ebola virus and released from hospital.
But medics were urgently seeking to contact around 50 others for testing, most of them from the northern town of Kambia, health ministry spokesman Harold Williams said.
‘Healthcare officials test around 50 others for ebola, most of them from the northern town of Kambia.’
Sierra Leone was forced to re-open its Ebola treatment centers and relaunch screening systems, including checkpoints on motorways, after two new cases of the tropical virus were confirmed.
"Forty-eight people are still classified as missing and 18 of them are high risk," he said, appealing for them to come forward. "We are only concerned about whether they are infected so that we can treat them to avoid any possible spreading of the virus," he said.
The remaining four people in quarantine were scheduled to be released on February 11.
There was a carnival atmosphere in the northern city of Magburaka where 33 people left two isolation facilities after being quarantined for three weeks.
Among the group were children, who celebrated after being told they had not shown any symptoms of being infected by the deadly tropical virus.
After their release, the town erupted in jubilation with hundreds of people taking to the streets in t-shirts reading "Stop Ebola" and "Ebola cannot defeat us", some carrying huge amplifiers blaring traditional music while others blew horns carved out of elephant tusks.
"It is good to breathe fresh air outside quarantine and rejoin friends and relatives to resume normal life," said Foday Kandeh, a 68 year-old farmer who grows groundnuts and said he'd missed drinking palm wine.
"It is an ordeal I never want to re-live," said Kadi Sesay, a 19-year-old student.
"Besides missing classes for 21 days, the quarantine period brought all of us together... The happy ending is that none of us tested positive but our thoughts were went into overdrive thinking what if we had," she said.
"Today is a new day for all of us."
Another 22 people were released from isolation facilities in Kambia, among them a herbalist who had initially provided traditional medicine treatments to 22-year-old Marie Jalloh, who died of Ebola on January 12, a day after west Africa had been formally declared free of the deadly tropical virus.
The deadliest outbreak in the history of the tropical virus wrecked the economies and health systems of the three worst-hit west African nations after it emerged in southern Guinea 2013. The outbreak infected almost 29,000 people and killed more than 11,300, mainly in Guinea, Liberia and Sierra Leone.