The case, confirmed this week after testing by the Pasteur Institute in Dakar and the National Institute of Biomedical Research, originated from a local mosquito, said the WHO's Eugene Kabambi, and therefore was not an imported case from neighbouring Angola.

The worst yellow fever outbreak in decades has killed 250 people in Angola and is straining global vaccine supplies, posing a dilemma for health officials who fear it could spread further in Africa and possibly into Asia.