Systematic review highlights knowledge gaps regarding which interventions really work for controlling cholera.
Dawn Taylor is the Water and Sanitation Advisor for Medecins Sans Frontieres in Amsterdam. Prior to her current role she studied her masters in Public Health in Developing Countries at LSHTM and then went on to work as a researcher within the Environmental Health Group. Dawn has a wealth of experience in responding to cholera outbreaks and through her work realised that too often the WASH interventions to address cholera are not always based on strong evidence.
To explore this further Dawn and her colleagues recently conducted a systematic review of the evidence around WASH interventions which are commonly used to control cholera. The full published article is available here via the PlosOne website. We asked Dawn some questions about the significance of the research:
Why is this study important?
Cholera remains a significant threat to global public health with an estimated 100,000 deaths per year. A wide variety of water, sanitation and hygiene (WASH) interventions are frequently implemented by responding organisations to the control outbreak but evidence on their effectiveness is often missing.
This review brings together a range of these interventions such as well chlorination, household water treatment, hygiene promotion and household disinfection and discusses the results and successes.
In the general WASH field the evidence is very limited on what works and what doesn’t, many studies do not adhere to the minimum standards of evaluation, often only stating how many households were exposed to an intervention without stating how many study participants had used the intervention, making it hard to recommend one intervention over the other.
In the emergency WASH field the evidence, as this survey showed, is even more limited, and the different organisations working in WASH emergencies have expressed their need for guidance on what to implement and where to use their limited resources. This systematic review is a first step to gather together current evidence and recommend the way forward.
What are the key findings of this study?
This review highlights a focus on particular routes of transmission, and the limited number of interventions tested during outbreaks. The majority of interventions tend to be related to water quality at source or point of use. We found that well chlorination is generally found to be ineffective in an emergency due the scale required and lack of trained staff. We would not recommend this is an outbreak. Furthermore hygienic water handling practices must be promoted otherwise any intervention at source will be undermined.
The most popular household water treatment option used to control cholera is the distribution of chlorine products. Our study found that these products are poorly used and depends on the availability and knowledge of the use. Distribution of these products must be accompanied by the appropriate education and will only likely be successful if the community is familiar with the products and willing to use them.
Despite the wealth of evidence for the promotion of hand washing with soap (HWWS) to reduce diarrhoeal disease, we were surprised at the lack of studies that evaluated hygiene promotion, with HWWS, for cholera control. Only one study presented results for self-reported use, and access to soap, which in itself can be subject to bias. The remaining 3 studies focussed on the effectiveness of hygiene promotion campaigns in changing behaviour and water treatment practices. Improved knowledge does not necessarily translate into improved practices, and as such there is a need to find ways to evaluate these interventions in more depth.
Finally we found that the practice of spraying the houses of cholera patients is ineffective and is increasingly being replaced with the use of household disinfection kits. The use of these kits may encourage sustained and improved hygiene at the household level and needs to being investigated further.
What were the key things you personally learnt while conducting the systematic review?
I think that the value of the systematic review lies in bringing together information that would otherwise remain isolated in the global evidence base. The key challenge for me was trying to describe a wide variety of relatively low quality studies according the standards required by PRISMA.
Our systematic review revealed a distinct lack of evidence for cholera control even though there are many international organisations out there responding every day. By publishing this review we hope to encourage organisations to integrate more robust research protocols into their response strategy, and make the necessary funding and resources available. The results of this much needed operational research will be invaluable to informing international WASH policy, standards and practice with the ultimate aim being, to contribute to reducing the global burden of cholera. Having started with this systematic review we hope to continue that process.