More than 100 of the 157 people suspected of being infected have died in Guinea, where the deadly hemorrhagic fever first struck in mid-March.
A mob in the south of that country has since attacked international aid workers, whom they blame for bringing in the disease.
Neighboring Liberia and Mali have also reported a few suspected infections.
Senegal has closed its land border with Guinea in an effort to keep the virus from spreading further.
Despite isolated resistance, WHO is rushing in workers to teach residents how to avoid being infected, and how to handle those who are.
“Ebola is clearly a severe disease. It’s an infection with a high fatality rate. But it’s also an infection that can be controlled,” said Keiji Fukuda, assistant director-general of the World Health Organization.
Photo: Doctors Without Borders