Liberian authorities on Tuesday quarantined two households after the corpse of a 17-year-old boy was found with Ebola, sparking fears the West African country could face another outbreak of the disease nearly two months after being declared Ebola-free.

"Liberia has got a re-infection of Ebola," Tolbert Nyenswah, deputy health minister and head of Liberia's Ebola response team, told The Associated Press.

The boy died at his home and was buried safely to avoid spread of the disease, Nyenswah said. The Nedowein area where he died is close to Liberia's international airport, about 30 miles (48 kilometers) south of the capital, Monrovia.

Teams are investigating how the boy became infected, Nyenswah said. The area is not near Liberia's borders with Sierra Leone and Guinea, neighboring countries that still have Ebola cases.

The World Health Organization declared Liberia Ebola-free on May 9, after it went 42 days without a new case. Liberia had been hardest hit with more than 4,800 deaths from this outbreak's total of more than 11,100 fatalities.

A single case of Ebola means a country has Ebola, said Dr. Margaret Harris, spokeswoman for WHO in Geneva.

Following the 42-day end of transmission period, there's a 90-day period of heightened alert with a surveillance system in place, Harris said.

"It does show that the system Liberia put into place is functioning well," she said, adding that it must be determined if this new Liberian case is isolated.

Ebola lingers in the body for a long time, said Ben Neuman, a virologist at the University of Reading in the U.K.

"The main concern here is: Did this man infect anybody else before he died?" Neuman said.

This is the only known case in Liberia for now, according to Liberia Ebola response chief Nyenswah.

The boy died on June 28 and was buried that day, said Liberian official Nyenswah, correcting his earlier statement that he died on June 24.

Food is being sent to the quarantined homes, he said.

Ebola is transmitted through direct contact with the bodily fluids of someone with the virus. The bodies of people killed by Ebola are also highly infectious.

The West African outbreak of Ebola is the worst ever recorded and the disease is hanging on stubbornly in Sierra Leone and Guinea, where Ebola was first reported in March 2014.