Not quite yet.

If the active surveillance for new cases that is currently in place continues, and no new cases are detected, WHO will declare the end of the outbreak of Ebola virus disease in Senegal on Friday 17 October. Likewise, Nigeria is expected to have passed through the requisite 42 days, with active surveillance for new cases in place and none detected, on Monday 20 October.

For Nigeria, WHO confirms that tracing of people known to have contact with an Ebola patient reached 100% in Lagos and 98% in Port Harcourt. In a piece of world-class epidemiological detective work, all confirmed cases in Nigeria were eventually linked back to the Liberian air traveller who introduced the virus into the country on 20 July.

The anticipated declaration by WHO that the outbreaks in these 2 countries are over will give the world some welcome news in an epidemic that elsewhere remains out of control in 3 West African nations.

In Guinea, Liberia, and Sierra Leone, new cases continue to explode in areas that looked like they were coming under control. An unusual characteristic of this epidemic is a persistent cyclical pattern of gradual dips in the number of new cases, followed by sudden flare-ups. WHO epidemiologists see no signs that the outbreaks in any of these 3 countries are coming under control.

How does WHO declare the end of an Ebola outbreak?

A WHO subcommittee on surveillance, epidemiology, and laboratory testing is responsible for establishing the date of the end of an Ebola outbreak.

The date is fixed according to rigorous epidemiological criteria that include the date when the last case with a high-risk exposure completes 21 days of close medical monitoring and tests negative for the virus.

According to WHO recommendations, health care workers who have attended patients or cleaned their rooms should be considered as “close contacts” and monitored for 21 days after the last exposure, even if their contact with a patient occurred when they were fully protected by wearing personal protective equipment.

For health care workers, the date of the “last infectious contact” is the day when the last patient in a health facility tests negative using a real-time reverse-transcriptase polymerase chain reaction (RT-PCR) test.

Read the complete WHO advisory here.