Health workers have warned that the outbreak, already one of the worst in decades, could take as long as a year to contain if infection rates do not flatten.
Aid agencies are racing to help health workers in the Democratic Republic of Congo. The virus is known to have killed at least 140 people, but the true toll may be far higher.
An Air France plane was sent to Montreal because a passenger from the Democratic Republic of Congo was on board. The U.S. has closed its borders to recent visitors to the African country.