An outbreak of haemorrhagic fever has killed at least 23 people in Guinea's southeastern forest region since February, when the first case was reported, health authorities in the West African nation said.
At least 36 cases have been recorded by local health officials, said Sakoba Keita, the doctor in charge of the prevention of epidemics in Guinea's Health Ministry.
"Today, we have recorded 36 suspected cases and, of those 36, there have been 23 deaths in the prefectures of Gueckedou, Macenta specifically," Keita told Reuters news agency.
"The investigation team is going from village to village to figure out what was the source of this. That's why, for the moment, we cannot rule out Lassa fever, Ebola or Leptospirose, or the other sicknesses that are haemorrhagic fevers," Keita added.
No cases of the highly contagious Ebola fever have ever been recorded in the country.
Keita said most of the victims had been in contact with the deceased or had handled their bodies. He said those infected had been isolated and samples had been sent to Senegal and France for further tests.
A doctor in the capital Conakry, Dr. Ce Maomy, said on Thursday that the mysterious fever was worrying.
"Listening to the news and to see the effects of what is happening in the forest, it's true that a mysterious fever is striking the people. It's scaring us," he said.
More than half of the mineral-rich nation's 11.4 million people live on less than $1 a day and many lack access to basic medical facilities and qualified medical staff.