Liberia vows to be vigilant to keep Ebola-free as country goes 42 days without a new case after a year-long epidemic that killed over 4,700 people. (Reuters)

The worst Ebola outbreak in history is officially over in one of Africa’s hardest hit countries, the World Health Organization announced Saturday.

Liberia, the West African nation where Ebola claimed the highest number of deaths in the largest outbreak since the virus emerged in 1976, has gone 42 days without any new Ebola cases, according to a statement released by the WHO.

The 42-day period represents double the maximum incubation period for the virus since the last victim of Ebola was buried.

The announcement marks a return from the brink for Liberia. During the outbreak’s peak in August and September, the statement said, the country was reporting from 300 to 400 new cases every week.

At the time, the WHO noted, the virus paralyzed the country of 4.2 million people, leading to canceled flights, fuel shortages and the closing of schools, businesses at health facilities. In the capital city of Monrovia, reports emerged of locals dumping the bodies of suspected victims in the streets while hospitals shuttered because health workers were too frightened to work.

With the nightmare fresh in their memories, officials urged residents not to let their guard down in Ebola’s absence.

“We are out of the woods,” Liberia’s Information Ministry said on its Twitter account Saturday. “We are Ebola free. Thanks to our partners for standing with is in the fight against Ebola. We are Liberians.”

Liberian President Ellen Johnson Sirleaf on Saturday referred to the devastation endured  by her country as “a scar on the conscience of the world,” according to the AP.

For some survivors, she added, “The pain and grief will take a generation to heal.”

Following Liberia’s announcement, the White House press secretary Josh Earnest released a statement praising the milestone and highlighting the Obama administration’s continued support.

“We congratulate the people of Liberia on reaching this important marker, and once again pledge our commitment to ending the Ebola outbreak in West Africa and helping to rebuild Liberia and other affected nations,” the statement said. “As President Obama said when Liberian President Ellen Johnson Sirleaf visited the White House last month, ‘“We’re proud to partner with you and we intend to see this through until the job is done.’”

Since Liberia’s latest outbreak began in March 2014, the country has seen more than 3,000 laboratory-confirmed cases of Ebola and another 7,400 probable cases, leading to more than 4,700 deaths, according to the WHO. A total of 375 health workers were infected and 189 lost their lives.

“Though the capital city was hardest hit, every one of Liberia’s 15 counties eventually reported cases,” the WHO statement said. “At one point, virtually no treatment beds for Ebola patients were available anywhere in the country.”

The country’s last victim, according to the WHO, was a Monrovia-area woman who died on March 27 and whose case remains under investigation. After close monitoring, the WHO noted, none of the 332 people who may have been exposed the the woman have developed symptoms.

Civil war and chronic poverty left a shortage of doctors and nurses in West Africa when Ebola swept through region last year. Early on, health workers didn’t realize they were dealing with an Ebola outbreak and when seemed to diminish, officials became overconfident. By the time the virus made the leap from rural villages to crowded cities, health workers spent grueling months struggling to catch up.

“The communities were the heroes in this fight,” Hassan Newland, who worked with UNICEF in Monrovia last fall told NPR. “They took on Ebola and decided enough is enough.”

Newland told NPR he credited neighborhood groups that rooted out the virus by going house by house, slowly turning the tide on the outbreak.

“They were locating the sicknesses themselves,” Newland said. “They were reporting the cases themselves. So when they decided to get involved we started to defeat Ebola.”

New Ebola cases continue to be reported in the two other countries hardest hit by the virus. Both Sierra Leone and Guinea, each of which share a border with Liberia, confirmed nine new cases last week, the lowest weekly total in 2015, according to the WHO.

There have been more than 3,000 cases in Guinea and more than 8,500 cases in Sierra Leone, which has had the highest number of cases of any country since December, according to WHO figures.

With Ebola still plaguing the region, the WHO has recommended that Liberia maintain a state of “heightened surveillance” for the next 90 days due to the possibility of the virus being transmitted through sexual contact with a survivor or through an animal host.

Mamudu Salifu, Oxfam’s Country Director in Liberia, said in a statement that the Liberian government recognized early on that working with “ordinary people” was a better strategy for combating Ebola than “forcing health measures on them” because it lessened the fear and mistrust surrounding the virus.

“Liberia, Sierra Leone and Guinea should now work together to ensure the region as a whole achieves zero cases,” the statement said. “Building people’s trust is crucial and working with communities should be a priority if the region hopes to reach zero and stay there.”

With the virus continuing to spread on Liberia’s border, officials said they are cautiously celebrating the end of the Ebola considering months of hard work could be undone with a single infected individual slipping across the border, according to the AP. Officials plan to continue monitoring border areas for sick travelers, “testing all dead bodies for the virus and conducting burials with specially trained teams wearing full protective gear,” according to the New York Times.

“We’re proud of what we collectively managed to do, but we need to remain vigilant,” Peter Jan Graaff, the U.N. secretary general’s acting special representative and head of the United Nations Mission for Ebola Emergency Response (UNMEER) told the AP. “The virus is not yet out of the region, and as long as the virus is in the region, we’re still all of us potentially at risk.”

The Ebola epidemic, which began in southeastern Guinea in December 2013, is believed to have killed more than 10,600 people and infected 25,791 in Guinea, Sierra Leone and Liberia, according to the WHO.

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