MONROVIA, Liberia — 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 Tolbert Nyenswah said.

The boy died at his home Sunday 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, 30 miles south of Monrovia.

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.