Update: Just hours after the WHO made its announcement on Thursday, officials from Sierra Leone confirmed a woman who died earlier in the week tested positive for Ebola. A statement from the WHO said the case reflected the ongoing risk of flare-ups. The woman potentially exposed up to 27 people, according to Reuters.
- The World Health Organization on Thursday declared Liberia to be free of Ebola, marking the first time in the two years all three West African countries hit by the tragic epidemic have seen no new cases in 42 days.
- Sierra Leone beat back the disease in November of last year, followed by Guinea in December. Forty-two days represents two full incubation cycles of Ebola, and is used as a standard timeline to judge whether the disease's spread has been halted.
- Liberia previously stopped the transmission of Ebola in May, 2015, but the disease flared up twice since then. The WHO cautioned robust surveillance and medical response will still be needed in the country for some time.
The West African Ebola epidemic, which began in December, 2013 in Guinea, infected nearly 29,000 people and took the lives of about 11,300 people worldwide. The epidemic severely strained the healthcare systems of Guinea, Sierra Leone, and Liberia, and highlighted deficiencies in the global capacity to handle major health epidemics in Africa.
The World Bank in April, 2015 estimated the effects of the epidemic cost the three countries a total of $2.2 billion in GDP. Sierra Leone's economy was hit the hardest from the outbreak, with a loss of $1.4 billion in GDP (out of the broader $2.2 billion figure).
In its announcement, the WHO warned that all three countries remain at high risk for additional outbreaks. Although transmission has been halted, the virus can remain in survivors and be re-transmitted. Male survivors have to be particularly careful as the virus can be present in semen for up to one year following infection.
There have been ten new flare ups of the disease identified by the WHO to date. The organization will continue to work with the three countries to screen for Ebola.
Yet, reaching zero new cases in all three countries is a hugely significant milestone.
"Detecting and breaking every chain of transmission has been a monumental achievement,” said Dr. Margaret Chan, the Director-General of the WHO. “So much was needed and so much was accomplished by national authorities, heroic health workers, civil society, local and international organizations and generous partners.”