Two more people have contracted the Ebola virus in Liberia, one day after the body of a 17-year-old boy was found tested positive for the virus and nearly six weeks after the country was deemed free of it by the World Health Organization (WHO), according to Liberia’s Ministry of Information.

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

Massaquoi told the New York Times that his team was hoping to determine whether it was an “isolated outbreak or new strain of the virus.”

“The Ebola fight is not over, but we must not lose hope,” Dr. Bernice Dahn, Liberia’s minister of health, said. Officials are now calling for calm, in hopes that the recent cases do not mark a return of an outbreak.

“It is critical that Liberians and all those residing in our borders remain vigilant, do not panic and continue all the preventive measures to stop this thread,” said Dahn.

These two people lived with the 17-year-old victim, who has been identified as Abraham Memaigar, at his home in a community called Smell-No-Taste. The city is approximately 30 miles from the country’s capital of Monrovia, according to BBC Africa, and has been frequently cited in the media’s coverage of the outbreak.

Memaigar first became ill on June 21 after showing symptoms of a virus at a local health facility, where he was treated for malaria and discharged. He died one week later. The early symptoms of Ebola can mimic many other far more common viruses, including malaria.

“An oral swab taken before the burial subsequently tested positive twice for [Ebola],” reported the WHO, which added that while more than 100 contacts have been identified, that number is expected to grow. “At this stage the origin of infection is not known. The case reportedly had no recent history of travel, contact with visitors from affected areas, or funeral attendance,” it adds.

In a tweet, a public health physician working at the International Rescue Committee said the latest cases show the “limits” of the “Ebola-free concept when surrounding countries [are] still epidemic and Liberian health system far from fixed.”

While Liberia had been pronounced Ebola-free on May 9, neither of its neighbors that were also hard-hit have reached that goal. Cases continue to show up in both Sierra Leone and Guinea.

In fact, the virus may soon hop yet another border, since at least four cases of Ebola were recently detected in the northern Guinea prefecture of Boke, which borders the nation of Guinea-Bissau. That country has not yet had a case of Ebola. Because of fears that the disease may cross another border, the WHO has deployed two epidemiologists and two community engagement experts to Guinea-Bissau.

There have been nearly 27,500 reported confirmed, probable and suspected cases of the Ebola virus in the three countries, with more than 11,000 reported deaths, according to the WHO’s latest situational report, which was released on Wednesday. Twelve new confirmed cases were reported in Guinea in the past week and eight in Sierra Leone.

Some information in this report is provided by The Associated Press. Andrew Freedman also contributed to this report.