"Two more people have been confirmed positive. These people had contact with the boy. We are still waiting for more results of blood tests," said health official Cestus Tarpeh.
Tarpeh, a spokesman for the health department in Margibi County, where the 17-year-old got sick, told AFP a herbalist who had treated him had evaded the authorities and was on the run.
The news came a day after Health Minister Bernice Dahn announced the boy - who has not been named - had died at a village near the west African nation's international airport, about an hour's drive southeast of Monrovia.
Dahn told reporters on Tuesday it was "likely that we will find additional cases" among the people with whom the unnamed boy had had contact.
The case comes with the country still reeling from a nightmarish outbreak which wrecked its health service and economy and left 4,800 Liberians dead.
Liberia had diagnosed its last victim, the wife of a cured patient, on March 20 - its only case in more than a month - and was finally declared Ebola-free on May 9.
Follow NDTV for latest election news and live coverage of assembly elections 2019 in Maharashtra and Haryana.
Subscribe to our YouTube channel, like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.