Those closely watching the Ebola virus disease (EVD) outbreak  – or any outbreak – will have noticed that some of the daily numbers go up and down very quickly. This churn is mostly due to the suspected cases; ill people who have signs and symptoms of disease that cannot easily be distinguished from those due to infection by Ebola virus without the use of laboratory testing.

Hopefully suspect cases also have some travel history to a house, village, town or city where a known case(s) was identified and contact with a known EVD case. I say hopefully because there are sometimes requests during an outbreak, for testing for an emerging or outbreak virus even though it’s incredibly unlikely that the suspected person was ever anywhere near a location of the active outbreak or had any contact with a known or probable case. This can waste precious time and resources. 

A new graph I’ve thrown together highlights the churn in suspected (green bars) EVD cases. It also shows that from 25th May 2018 onwards, laboratory-confirmed EVD cases (pink bars) have been rare. The rapidly changing suspected case numbers underline how active the surveillance teams have been and how successful they are at finding ill patients of concern, testing specimens and (mostly) finding them to be ill due to something that is not Ebola virus.

Churn is a good sign because it suggests that the laboratory testing is working well and turning around results quickly.

Another encouraging sign is the slowing number of confirmed Ebola virus cases.