The Ebola death toll in Guinea has risen to 80, while 122 suspected cases have been registered, health authorities said Tuesday.
The outbreak was "unprecedented" because the spread of the disease across the small West African nation made it very difficult to control, Medical charity Medecins Sans Frontieres (MSF) warned.
"We are facing an epidemic of a magnitude never before seen in terms of the distribution of cases in the country," said MSF project coordinator Mariano Lugli.
President Alpha Conde announced a "health emergency," but snubbed Guinea's northern neighbour Senegal, which closed its borders to protect its population from the virus, for "causing panic."
In Liberia, to Guinea's south-east, at least two people died from the virus. The health ministry announced at least 11 suspected cases last week. Ebola is one of the most contagious viral diseases known, often resulting in death.
The virus cannot be prevented with a vaccine and is untreatable with medication.