Friday 31 October 2014

The bad the worse and the over-interpreted...

EVD case numbers between WHO reports. 
The World Health Organization (WHO) Ebola virus disease (EVD)case numbers that came out on 29-Oct were pretty big (see graph on the left). As if there weren't already enough new cases and deaths every 2-5 days, now there is this bolus of 3,562 cases added to the total. And a net change in deaths of -2? What the heck?  

Let's see if we can add some context.

According to a number of past WHO reports, a lot of effort has been going in to trying to collect data more effectively including improving the linkage of lab results to cases, cases to deaths, lab data to deaths and probably a million other things. 

Dr Bruce Aylward
In the previous Roadmap SitRep and Roadmap update, the Liberian numbers did not move - they even had the same date. That was new and it was concerning because it suggested that reporting had been stopped or collapsed entirely. However this new large download of cases is in some way good news because it suggests reporting is working and the systems and processes are coping - although undoubtedly still stressed - again. 

The thing to be aware of is that these are not cases that have all been detected or all occurred since the last report 5 days previously. According to Dr Bruce Aylward, WHO Assistant Director-General, Polio and Emergencies, during a preceding media conference (and my thanks Martin Enserink for asking the important question; underlining is mine)..

In terms of the jump in the number of cases, one of things that we've talked about in the past on this is that with the huge surge in cases in certain countries, particularly in September and October, people got behind on their data.
They ended up with huge piles of paper in terms of cases, etc, and we knew and I actually said to you the last time, we are going to see jumps in cases at certain times that are going to be associated more with new data coming in but it's actually on old cases.
And a couple of days there were about 2,000 additional cases in, if I remember correctly, it was actually the Liberia case report but most of these were old cases because remember they got swamped a couple of months ago with a lot of new cases and just got behind on their data, so a lot of that is about reconciling new data.
If we look at sort of a seven day rolling average number of cases which have been around 1,000, just under that, about 900, there hasn't been a big change in that in the recent weeks.
So the 3,562 cases come largely from the past as well as the present. It's not that the sky has fallen in the past 5 days. Which is good news. But of course, that puts us back to "just" 1,000 or so Ebola virus disease cases a week. In other words, in just 1 week there are more cases than in any individual outbreak since 1976. 

The cumulative EVD case curve at 29-Oct
However, this week has seen a few articles and comments noting that the number of new cases in parts of Liberia seem to have fallen slightly. 

This seems to be a real trend in that there are fewer burials and more empty treatment beds and fewer cases found when sought in the community. Why there are fewer is not precisely known and it is far to early to rely on this yet. But we do know that there are better numbers of safe burials, better education, more experience with the disease, more help and facilities and more PPE comapred to when this started. 

The three countries with intense transmission still require a lot of help from us though - that urgency must not let up. Remember that cases had dropped a lot back in May - and now look where we are.  

If you can't get there in person to offer specialist help, and most of us cannot, keep bringing the issue to the attention of your country's leaders, learn about the virus and the disease from trusted sources and help teach others and head off ignorant comments, and donate some (some more) money to those groups who can make a real difference on your behalf (I've listed some great options here). 

Fighting the fire at its source is still the best way to help save lives in Guinea, Sierra Leone and Liberia and to stop new outbreaks from occurring in other countries.


  1. WHO Ebola Roadmap SitRep#10
  2. Virtual Press Conference transcript

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