Wednesday, 28 January 2015

Are fewer Ebola virus disease cases being confirmed than previously?

A very quick graph plotting the proportion (percentage, %) of laboratory-confirmed Ebola virus disease (EVD) cases reported by the WHO over time. That is, the of samples taken from clinically suspected EVD cases that are RT-PCR positive for Ebola virus in a given report, divided by the total number of suspected + probable + confirmed cases in that report.

Taken from my static
EVD tallies and graphs
page here
. Updated
28JAN2015 AEST.
Click on graph to enlarge. 
Looking at the graph below, it seems like a lower proportion of total cases are being confirmed now compared to before the total case load began decreasing (especially from December onwards-see adjacent graphic). 

Presumably this is due to the larger number of other infectious diseases in the region that cause signs and symptoms, especially early signs and symptoms, that cannot be easily clinically differentiated from EVD; more suspect cases that don't test positive for EVD than before.

When considered in the context of the now smaller number of EVD cases overall, the non-EVD infection's background "noise" has become louder.

But the bottom line is that EVD cases are steadily declining thanks to the many efforts of many people and the changes to habits, traditions and practices that increased risky contact.

The proportion (%) of EVD detection that are laboratory confirmed at each World Health Organization Situation Report or Situation Summary. Anomalous values have been removed. Click on graph to enlarge.