The World Health Organization (WHO) says the Ebola epidemic that has ravaged West Africa for two years is over after Liberia, the last affected country, received the all-clear, but that additional small outbreaks could not be ruled out.

“Today the World Health Organisation declares the end of the most recent outbreak of Ebola virus disease in Liberia and says all known chains of transmission have been stopped in West Africa,” the UN health agency announced in Geneva.

Guinea, Liberia and Sierra Leone “remain at high risk of additional small outbreaks of Ebola”, it added.

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The announcement came 42 days, or two 21-day incubation cycles of the virus, after the last confirmed patient in Liberia tested negative twice for the deadly disease.

The deadliest outbreak in the history of the feared tropical virus wrecked the economies and health systems of the three worst-hit West African nations after it emerged in southern Guinea in December 2013.

At its peak, it devastated Guinea, Liberia and Sierra Leone, with bodies piling up in the streets and overwhelmed hospitals recording hundreds of new cases a week.

The outbreak infected almost 29,000 people and claimed 11,315 lives, according to official data.

Liberia, the country worst hit by the outbreak with 4,800 deaths, discharged its last two patients from hospital — the father and younger brother of a 15-year-old victim — on December 3, 2015.

The real toll is suspected to be much higher, with many Ebola deaths believed to have gone unreported.