FREETOWN, Sierra Leone (AFP) — 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, November 7, 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 September 25, three weeks after the WHO had declared neighbouring Liberia Ebola-free following 4,800 deaths there.