Health workers leave after they took a blood specimen from a child to test for the Ebola virus in a area were a 17-year old boy died from the virus on the outskirts of Monrovia, Liberia, Tuesday, June 30, 2015. (Abbas Dulleh /AP)

Liberia confirmed a second Ebola case on Wednesday and warned of possible new infections as the reemergence of the virus several weeks after its elimination in the West African country raised fears of hidden pockets of the disease.

More than 11,200 people have died since last year in the worst Ebola outbreak on record, nearly all of them in the three neighboring countries of Liberia, Sierra Leone and Guinea.

Liberia, where 4,800 people perished, had been viewed as a rare success story, having been declared Ebola-free May 9.

But Tuesday’s confirmation of an Ebola case in a rural area of Margibi County, about 30 miles from the capital, Monrovia, raised fears of a resurgence of the disease.

The World Health Organization (WHO) said Liberian authorities were monitoring more than 100 people thought to have come into contact with Abraham Memaigar, who died Sunday.

The 17-year-old, initially misdiagnosed with malaria, was buried the same day, but tests on his body confirmed his infection. A neighbor later tested positive.

“We have two confirmed cases today in Liberia,” Moses Massaquoi, case management team leader for Liberia’s Ebola task force, said Wednesday.

Some residents of Memaigar’s village said that those showing symptoms of Ebola had recently eaten a dog, a practice common in Liberia. In past outbreaks, humans have been infected by eating monkey flesh.

“This might mean that there is a reservoir of Ebola in animals that we have not been paying attention to,” Philip Ireland, an Ebola survivor, said at John F. Kennedy Medical Center in Monrovia. “It could pop up anywhere.”

In the village of Nedowein, Memaigar’s mud-brick home was under quarantine Wednesday. Health officials wearing rubber boots and gloves went from house to house talking to residents confined to their homes.

“At present we have four people of high risk that have been taken to . . . Monrovia. They are all from the community,” said John Sumo, a member of the incident management team.

Ebola, spread through bodily fluids, is most contagious in the late stages, when victims can suffer bleeding from the eyes and ears as well as vomiting and diarrhea.

The disease can remain present in semen long after a patient is cured. It is also possible that the new infections resulted from a previously unidentified pocket of the disease. Ebola is now thought to have been present in an area straddling the three countries long before the current outbreak was identified.