Barely two months after the World Health Organization declared Sierra Leone to be Ebola-free, local officials on Sunday confirmed a new death caused by the disease, according to the Agence France-Presse. Officials also stated that 109 people, 28 of whom are considered to be at high risk for infection, had been quarantined in an attempt to prevent the disease’s further spread.

"We are worried and concerned about this new development but call on the general public not to panic ,” Ishmael Tarawally, the national coordinator of Sierra Leone’s Office of National Security, said at a press conference. “More than ever before, all Sierra Leoneans must work together to prevent further infection."

The victim, a 22 year-old woman whose identity has not yet been released, died in Magburaka, the largest city in the northern district of Tonkolili. According to the World Health Organization, she fell ill near the Guinean border last week, but presented no visible signs of being infected with Ebola when she visited the Magburaka Government Hospital. Sierra Leone’s chief medical officer, Dr. Brima Kargbo, said that the government would “revisit” the Ebola case definition.

Ever since an outbreak of Ebola first erupted in Guinea at the end of 2013, it has terrorized West Africa, killing more than 11,000 people, the vast majority in countries including Sierra Leone, Guinea and Liberia, which all border one another. The Centers For Disease Control and Prevention reported that other deaths were confirmed in Mali, Senegal, Italy, Spain and Portugal.

Public health officials in the region thought they had reason to breathe a sigh of relief, after the WHO pronounced Liberia to be free of Ebola cases. Last month, Guinea had heard the same, though all three countries were in the midst of a 90-day period of enhanced surveillance. 

Tarawally also said that active case investigations are underway in three separate locations where the victim is reported to have traveled, including Kambia, Port Loko, Bombali and Freetown.