Ebola cases exceed 1000 new cases per week

Based on World Health Organization  (WHO) data, in early September I projected that new Ebola cases would exceed 1000 cases per week by September 21, 2014 (link).  As of the most recent WHO update on September 26, 2014 ( with data current through September 23, 2014), the number of new cases exceeded 1000 in week number 39, starting on September 21. See graph below. 

WHO has not provided a more recent update of the Ebola cases counts. But given the multitude of media reports about many additional uncounted cases and deaths in several of these West African nations, the WHO numbers are probably very low and don't reflect the nature and severity of the Ebola outbreak that is evolving in West Africa.

By September 21, 2014 Ebola could be infecting more than 1000 people a week in Africa

A World Health Organization (WHO) official made a dire prediction about the Ebola outbreak today. Christopher Dye, director of strategy in the WHO Director General’s office, stated in a media interview

"If we make a simple projection on what has happened over the last, say, 10 weeks ... and make a projection forward, then what we're faced with is not hundreds of cases a week, which is what we see at the moment, but thousands of cases a week going into next month.”

Based on WHO data, graphing the number of new Ebola cases for each of the last 10 weeks does show the increasing rate of cases each week. After applying a trend line to the data, week number 39 starting on September 21, 2014 appears to be the week when the 1000-cases-per-week milestone will be passed (see graph below). Given the reporting delays in case numbers, this milestone may not be confirmed until a week or two later. 

While media pundits like round numbers and milestones to emphasize talking points, there is nothing unique about a week with 1000 Ebola cases versus 800 cases the week before or perhaps 1300 cases a week later. The focus should be on implementing a plan to reduce the transmission of Ebola in these areas and provide care and services to the unfortunate victims. 

Graph: Projection of the number of new Ebola cases in Africa within the next several weeks, September 5, 2014  

Graph notes: Only cases from the Ebola outbreak in Guinea, Liberia, and Sierra Leone are used in this graph. The cases from Nigeria are not included in the week totals, but would not appreciably affect the projected rate of growth of new cases. All data are from WHO.

Ebola infections in West Africa continue to grow

In a previous post (Ebola is not yet under control in any West African country), I criticized an article that suggested that Ebola infections were declining in several countries in West Africa because the effective reproductive rate was less than 1. 

The graph below depicts the number of new weekly infections in the three West African countries (Guinea, Liberia, and Sierra Leone).  Cumulatively, the number of Ebola infections is continuing to grow. The World Health Organization has indicated today (link) that these countries have widespread intense transmission of Ebola. 

Graph notes: The data used in this graph are derived from World Health Organization and are current through August 31, 2014. Graph notes: Only cases from the Ebola outbreak in Guinea, Liberia, and Sierra Leone are used in this graph. The cases from Nigeria are not included in the week totals, but would not appreciably affect the projected rate of growth of new cases. All data are from WHO.