Freetown: The World Health Organization said on Saturday that Ebola-ravaged Sierra Leone had beaten an 18-month outbreak that killed almost 4,000 citizens and plunged the economy into severe recession.

The former British colony recorded around half of the cases in an epidemic that has infected 28,600 people across the three hardest-hit west African nations and claimed 11,300 lives since December 2013.

Experts agree that the real death toll is almost certainly significantly higher than the official data, which has been skewed by the under-reporting of deaths in many probable Ebola cases.

“Today, 7 November 2015, the World Health Organization declares the end of the Ebola outbreak in Sierra Leone," Anders Nordstrom, the UN agency’s country representative, told a ceremony in the capital Freetown, to rapturous applause.

The announcement represents a hugely significant milestone in UN-backed efforts to wipe out Ebola, leaving neighbouring Guinea as the only country still registering cases.

With just a handful of infections a week arising in that country in recent months, health campaigners are hopeful the battle with history’s worst outbreak is almost won.

A country is considered free of human-to-human transmission once two 21-day incubation periods have passed since the last known case tested negative for a second time.

The crisis took a devastating toll on primary health services and immunisation programmes, with the deaths of 221 medical staff in Sierra Leone.

After some false starts, Sierra Leone’s countdown finally began on 25 September, three weeks after the WHO had declared neighbouring Liberia Ebola-free following 4,800 deaths there.

Guinea, where around 2,500 died, still has a handful of cases and Sierra Leone has announced heightened security and health screening at their shared border.

All three countries have been at pains to point out that the end of an outbreak does not necessarily mean Ebola is gone for good.

But international and local authorities say the expertise they gained in healthcare, communications, epidemiology and public policy places them in a far better position to mount an effective response in the future.

“Ebola has ended but we must be prepared for a re-emergence and we are retaining some laboratory testing capacities and treatment centres. But we are confident we now have a system in place to respond," President Ernest Bai Koroma told the Freetown ceremony.

He said he was in discussions to end a national state-of-emergency that has placed severe restrictions on movement, and announced two public holidays before the end of the year to give thanks and recognise the bravery of those fighting the outbreak.

“The heroism of the 35,000 Ebola response workers is without parallel and I am here today as head-of-state to say we have overcome the virus," Koroma said.

Thousands took to the streets late Friday to light candles, wave banners, sing and dance in an impromptu celebration centred around the iconic cotton tree in Freetown’s downtown area.

The celebrations continued into the morning, with bars and restaurants offering free drinks to the revellers.

The steep hills surrounding the city of 1.2 million reverberated with the crackle of fireworks while church bells rang out and the Muslim population offered prayers in the city’s mosques.

The epidemic was first reported in Sierra Leone 18 months ago, when a woman tested positive after contracting the virus at the funeral of a healer who had been treating Ebola patients in Kailahun district on the Guinea border.

At the peak of the outbreak in 2014, Sierra Leone and its neighbours were reporting hundreds of new cases a week, with social order on the brink of collapse.

Villagers beat drums and danced to traditional music as the WHO’s announcement was broadcast in Kailahun, in the remote eastern jungle.

“Everybody was in jubilant mood, many of them said they felt relieved and are now planning to return to their farming activities in the cocoa and rice producing district," one local told AFP.

While the primary cost of the outbreak has been in human life, the crisis has also wiped out development gains in Sierra Leone, which was devastated by 11 years of civil war ending in 2002.

The World Bank estimates that the country will lose at least $1.4 billion in forgone economic growth in 2015 as a result, leading to an “unprecedented" GDP contraction of more than 20%.

Celebrations were muted in part by memories of the devastation, and across the country, Ebola workers recounted their own personal horror stories.

“I hated the smell of chlorine. They say you only die once, but I died several times. But it is good it is now over," ambulance driver Ferenka Koroma told AFP. AFP