Evaluating communicable disease surveillance in resource-poor settings : a new approach applied to meningitis surveillance in Chad

Background The costs of improving surveillance systems in resource-poor settings are largely unknown. Though several communicable disease surveillance systems have been evaluated, they rarely provide precise evidence to facilitate decision making or support appeals to increase and sustain surveillance system investments. This thesis seeks to empirically test the potential benefit of a novel evaluation approach, which assesses both cost and performance of surveillance. Methods The thesis and PhD research compromises four components: 1) a structured literature review to describe and examine evaluation methods of communicable disease surveillance systems; 2) an application of the ingredients costing approach to retrospectively determine meningitis surveillance costs in Chad in 2012; 3) a work-process analysis structured evaluation and identification of performance gaps through interviews at health facilities and at each administrative level across seven districts in southern Chad; and 4) an estimation of the costs to upgrading and implementing a more sensitive system to assess the long term impact of the newly introduced serogroup A meningococcal conjugate vaccine in Chad. Results The literature review highlighted the necessity of granular evaluation methods in low-resource settings where surveillance data at supra-peripheral levels are less reliable. In Chad, optimal surveillance was severely hampered by limited resources. Only four percent of probable meningitis cases had a known outcome. Missing and unreliable data affected case detection; in three of the districts, zero meningitis cases were reported during 2012. In the other four districts, reported cases varied between 11 and 149 per 100,000 populations. The total costs of meningitis surveillance in Chad were estimated at US$ 393,000, equivalent to US$ 0.03 per capita. The work-process analytic 3 approach was used to detail an upgrading plan of resources and inputs and a 123% incremental increase in annual costs was estimated as needed to upgrade meningitis surveillance to an optimal standard. Sentinel district case-based surveillance was recommended as the most feasible and sustainable strategy. Conclusion The systematic approach for assessing performance gaps and the associated costs provided rich data that stakeholders found useful for policy and programme change. This approach underscores the benefit of understanding specific contexts in order to yield the most relevant and meaningful evidence for surveillance system strengthening.