A young girl, who contracted Ebola in Guinea, died in the latest flare-up of the epidemic that has killed thousands of people in the country as well as Sierra Leone and Liberia since 2013, Reuters reported Saturday. The latest death, the fourth in the country, comes even as the World Health Organization (WHO) declared the flare-up to have ended in neighboring Sierra Leone Thursday.

Fode Tass Sylla, spokesman for the center that coordinates Guinea's efforts to tackle the Ebola virus, said, according to Reuters: “The young girl who was hospitalized at the Ebola treatment center in Nzerekore [city] is dead.” It was not immediately clear on how many people from Korokpara, about 60 miles from Nzerekore, have contracted Ebola, but the area had resisted efforts to fight the Ebola virus during the initial epidemic.

The report added that three others have died due to the disease since Feb. 29, while health workers in the region increased their efforts Saturday to track those who could have come in contact with the girl’s family. The disease, which killed over 11,300 people in Guinea, Sierra Leone and Liberia, is believed to have started in Guinea, according to Reuters.

The Ebola virus had killed about 2,500 people in Guinea by December last year, when WHO said that the disease was not being transmitted actively anymore, Reuters reported. However, the organization warned that the disease could resurface anytime because the virus can linger on in the eyes, central nervous system and bodily fluids of some of the survivors.

WHO declared the flare-up of Ebola to have ended in Sierra Leone after 42 hours, or two incubation periods, had passed since the last known victim of the Ebola virus tested negative, the New York Times reported. However, Guinea announced that two people had tested positive for the virus, just hours after WHO’s announcement.

The virus has killed 3,590 people in Sierra Leone in the epidemic.