Ebola survivors leave a treatment center in Paynesville, Liberia, on October 12, 2014.

Story highlights

Liberia initially was declared Ebola-free in May after a deadly epidemic

But six more cases appeared from June to July

The outbreak has killed more than 11,000 people in three of the hardest-hit African nations

CNN  — 

Ebola’s recent reappearance in Liberia is over, the World Health Organization said Thursday, prompting the group to declare the country free of the deadly virus for the second time this year.

Liberia, one of three West African nations ravaged by an outbreak that has killed more than 11,000 people in nearly two years, initially was declared Ebola-free on May 9. But a teen who lived near a Liberian airport contracted the virus and died in late June.

Six total cases were discovered in the country from late June to July. Two people, including the teen, died, the WHO said.

Because 42 days have passed since the last infected person tested clear for the disease, the WHO said it could now declare Liberia free of Ebola. Forty-two days represents two maximum incubation periods.

Health workers in protective clothing speak with new arrivals at a hospital in Monrovia, Liberia, on February 2, 2015.

“WHO commends the government of Liberia and its people on the successful response to this recent re-emergence,” the organization said. “It is in full accord with government calls for sustained vigilance.”

More than 4,800 of the 10,666 people who contracted the hemorrhagic fever in Liberia died since that country’s first case was reported in late March 2014.

The outbreak has also killed thousands in Liberia’s northern neighbors, Guinea (2,500) and Sierra Leone (3,950), starting with the December 2013 death of a 2-year-old child in Guinea, the WHO has said.

Epidemic fading

But the epidemic that sickened more than 28,000 people in those three nations is winding to an end, with only a few cases remaining.

Just one new case was reported in Sierra Leone in the last two weeks. That country and Guinea have combined for three confirmed cases per week for the last five weeks, the WHO said.

That’s in stark contrast to the hundreds of new weekly cases that the three countries were seeing at the epidemic’s peak a year ago.

An experimental Ebola vaccine may be helping. The WHO in July declared the single-dose VSV-EBOV vaccine to be “highly effective” after it was given on a trial basis to 1,200 front-line health care workers and 4,000 close contacts of Ebola patients in Guinea this year.

The trial was extended to Sierra Leone last month after the latest Ebola case was reported there. People who were in contact with that patient were to be vaccinated, the WHO said.

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