WHO has released a report contradicting U.S. officials assessment of the Ebola incubation period..
In the WHO’s Ebola situation assessment newsletter released October, 14, 2014, it notes that 1 in 20 Ebola infections actually has an incubation period twice as long as the 21 days claimed by the CDC.
Are the Ebola outbreaks in Nigeria and Senegal over?
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.
The period of 42 days, with active case-finding in place, is twice the maximum incubation period for Ebola virus disease and is considered by WHO as sufficient to generate confidence in a declaration that an Ebola outbreak has ended.
Recent studies conducted in West Africa have demonstrated that 95% of confirmed cases have an incubation period in the range of 1 to 21 days; 98% have an incubation period that falls within the 1 to 42 day interval. WHO is therefore confident that detection of no new cases, with active surveillance in place, throughout this 42-day period means that an Ebola outbreak is indeed over.
If this interpretation of the WHO’s statistics are correct, it would mean that:
• 1 in 20 Ebola infections may result in incubations lasting significantly longer than 21 days
• The 21-day quarantine currently being enforced by the CDC is entirely insufficient to halt an outbreak