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A study modelling the effects of different types of interventions attempting to control Ebola in West Africa has been published in the journal Science. The researchers suggest that a number of practises already being implemented can be effective in limiting the spread of the disease, but that they would have been more effective at earlier stages of the outbreak.
Prof Andrew Easton, Professor of Virology, University of Warwick, said:
“This paper describes a modelling analysis of the current Ebola virus outbreak primarily using data from Liberia available to the authors at the time of writing. The primary conclusions are that the four key steps identified by WHO to control virus outbreaks do indeed appear to be highly relevant. These are: taking precautions to protect healthcare workers from infection, isolation of infectious patients, tracing contacts and subsequent quarantine to limit spread of infection, and precautions during burial of victims of the infection. The conclusions are that all of these are effective, with care during the burial of victims potentially having the greatest impact.
“An essential issue raised is the scale of under-reporting of cases which, if sufficiently large, will have a serious effect on estimates of the likely longevity of the outbreak and the ability of the current procedures to offer the possibility of control.
“Despite the issue of unreported cases, two important messages come from this study: firstly that effective implementation of the known protective procedures at an early stage would probably have limited the scope and scale of the infection, and secondly that same measures still offer the opportunity to bring the situation under control if they are implemented with sufficient rigour as soon as possible. This is a message that needs to be heard and appreciated.”
Prof David Evans, Professor of Virology, University of Warwick, said:
“This is one of several recent papers that attempts to predict the course of the Ebola virus outbreak in West Africa based upon historic outbreaks and current case numbers. It extends this analysis to investigate the differential impact of a variety of containment practices on the spread of the disease.
“In this study, the R0 calculated for Ebola virus – the basic reproductive number, or the number of new cases arising from each infected patient – was 1.63. The impact of reduced infections in hospitals, sanitary burial, isolation, contact tracing and quarantine on the R0 was then predicted. Of these, unsanitary burial practices had the most dramatic impact, alone reducing the R0 below 1. R0 must be below 1 for the outbreak to be controlled.
“In contrast, reductions in transmissions in hospitals and the community had a much less marked effect. Curfews and similar movement restrictions were also ineffective in controlling the outbreak and a previous attempt to impose these in the West Point slum region of Monrovia resulted in rioting.
“As awareness of the disease and routes of infection become more widely advertised and accepted it is likely that there will be a reduction in funeral transmission which, in previous outbreaks in DRC and Uganda, was already known to be important in controlling the disease. However, as the numbers of cases inexorably increases it becomes increasingly difficult to either trace contacts or – unless the scale of the relief effort is significantly increased – isolate them in hospitals.
“This paper does not fundamentally change our understanding of Ebola virus transmission and how to control it. It emphasises the importance of education of the population to achieve the maximum benefit. It also makes clear that the prompt application of these very same containment methods in March, April and May would have resulted in the outbreak being controlled by now.”
‘Strategies for containing Ebola in West Africa’ by Abhishek Pandey et al. published in Science on Thursday 30 October 2014.
All our previous output on this subject can be seen at this weblink:
http://www.sciencemediacentre.org/ebola-outbreak/
Declared interests
None declared