END OF EBOLA?

The article in the January issue about Ian Crozier, the doctor who beat Ebola and then had to contend with an instance of isolated recrudescence, was a real eyeopener. (Pun intended!) It made me think about various outbreaks that have come and gone. It’s easy to forget about them when they’re not front and center in our minds, but even after the news dies down the problem persists somewhere. What’s the current status of the Ebola epidemic? Is the outbreak completely over, or is there a chance it could return with full force again? Peter Stanton via email

Despite dropping out of the headlines, the Ebola outbreak is not quite over. In June of 2015 new cases of Ebola surfaced in Liberia, though the country had initially been declared free of Ebola virus transmission the month before on May 9. But on September 3 the World Health Organization once again declared Liberia free of the virus. In neighboring Guinea and Sierra Leone, though, limited Ebola cases are still occurring—albeit at levels nowhere near those seen at the height of the 2014 outbreak. A country is considered free of human-to-human transmission once 42 days have passed, marking two 21-day incubation periods. However, the risk remains for some time: Ebola pathogens have been found in the semen of male survivors up to three months after their blood samples have tested negative for the virus. As Francis Karteh from Liberia’s Ebola management department warns: “As long as there is one person with Ebola in our region, Ebola is still a threat.”