When the Ebola epidemic was terrifying the world a few months ago, experts measured its soaring growth rate by counting how swiftly the cases doubled. Today, there's a new metric: how fast they are halving.
For the first time, the worst seems over. The World Heath Organization on Thursday announced dramatic declines in the number of new Ebola cases in all of the hardest-hit countries of West Africa. As swiftly as it escalated, the crisis now appears to be receding.
The WHO and other experts are warning that it is much too early to be complacent, since Ebola has shown an ability to come roaring back as soon as the world loses focus. Intense hot spots remain, and the United Nations is still trying to raise a further $1-billion to help defeat Ebola completely by June.
But the figures on Thursday were encouraging. The number of new Ebola cases is now dropping in half every 10 days in Guinea, every two weeks in Liberia and every 19 days in Sierra Leone, the WHO reported.
In Liberia, there were more than 300 new infections a week at the peak of the crisis in August and September. That frightening rate has now tumbled to just eight new cases a week this month.
Sierra Leone, the country with the largest number of Ebola cases, had seemed to defy every effort at control. But now it, too, is showing dramatic progress. "Case incidence is decreasing quickly in Sierra Leone," the WHO said on Thursday.
There were 117 new confirmed cases in Sierra Leone in the week ending Jan. 18, the report said, compared with 184 in the previous week and 248 in the week before that. That is a dramatic improvement from the peak in December, when it was reporting 550 cases a week.
Sierra Leone announced on Thursday that the progress is allowing the country to plan on reopening schools in March. Schools have been empty since last July because of the Ebola emergency.
In Guinea, the number of new cases has dropped for three consecutive weeks. Only 20 new cases were reported in the latest week, less than half the number of the previous week. It is the smallest number of new cases in Guinea in more than five months. Guinea, too, is reopening its schools.
At the worst of the crisis, U.S. analysts were warning that there could be 1.4 million cases of Ebola by this year. Instead, there have been fewer than 22,000 officially reported cases. Small outbreaks of Ebola have been successfully contained in several countries, including Nigeria, Senegal and Mali.
The reasons for the breakthrough are many. The world's huge effort against Ebola, led by heroic health workers in West Africa itself, is finally paying off. The number of treatment beds has increased sharply, so that Ebola patients are not turned away from hospitals. Communities are more engaged in the battle against the virus, with greater awareness of how to prevent the infection.
Safe burials are increasingly common, so that mourners and grieving families are less likely to catch the virus from the dead. When outbreaks occur, contact-tracers have quickly tracked down and monitored everyone in contact with the virus.