enabled Red Cross staff and partners to decide whether follow up, investigation or response was required for alerts. Scripts in Rstudio were furthermore used to generate automatic epidemiological reports based on SMS database and case investigation data, and shared with stakeholders to monitor trends over time.Results: The CBS system had the sensitivity and specificity required to detect cholera outbreaks, as evidenced by comparing temporal variation in the rate of occurrence of cases in the CBS data with available line-list data from cholera treatment facilities. However, the data from the CBS system is noisy. Our results show positive proof of concept for disease surveillance by volunteers with mobile phones, and the ability, for the first time, to detect cholera in rural areas that are often missed in formal surveillance. Furthermore, our results illustrate that community-based surveillance works best when integrated with the formal healthcare system-coupling the high sensitivity and low specificity of community surveillance with the high specificity and low sensitivity of formal surveillance, which cannot always penetrate rural areas, or areas recently affected by environmental or humanitarian emergencies.Conclusion: Community-based surveillance is an important strategy to broaden the reach of public health surveillance to rural communities in resource poor settings, especially during outbreaks. The project demonstrates the potential for scale and sustainability by utilising existing volunteer networks in response to disease outbreaks.http://dx.

Purpose: The objective of this study was to explore the volunteers' experiences with and perspectives on the community event-based surveillance system in Sierra Leone.Methods and materials: 62 volunteers from 14 different chiefdoms participated in in-depth interviews and focus group discussions, which were audio recorded and transcribed. A comprehensive and systematic thematic analysis was conducted, which identified key benefits and challenges. Results:The volunteers believe CEBS positively impacts their communities. CEBS increases knowledge and behavior change, contributing to the prevention of Ebola and other diseases and decreasing overall mortality. Volunteers are motivated to participate by an aspiration of helping their community, although many volunteers also participated in the hope of receiving monetary incentives. Communities were initially reluctant to participate in surveillance due to fear of Ebola, but acceptance increased with improved community engagement. Reporting by phone call and SMS was perceived as a quick and simple way of reporting, although challenges with access to mobile network, sim registration and cost for charging were identified. Many of the volunteers could not repeat or explain the different case definitions and explained reporting on symptoms solely or other health events, suggesting that the volunteers did not have a clear understanding of case definitions or purpose of CEBS.Conclusion: SMS reporting directly from the community is perceived as a timely, easy and reliable way of sharing important information, but the usefulness of the system relies not only on the structure of the system itself, but also on external factors, such as the relationship between the community members and the volunteers, and the logistical structure.