Evaluation of the Measles Surveillance System in Kaduna State, Nigeria (2010-2012)

Abstract

ObjectiveTo evaluate the case-based Measles surveillance system in Kaduna State of Nigeria and identify gaps in its operation.Introduction In Africa, approximately 13 million cases of measles and 650,000 deaths occur annually, with sub-Saharan Africa having the highest morbidity and mortality (1). Measles infection is endemic in Nigeria and has been documented to occur all year round despite high measles routine and supplemental immunisation coverage (2,3). The frequent outbreaks of Measles in Kaduna State prompted the need for the evaluation of the Measles case-based surveillance system.Methods We interviewed stake holders and  adapted the updated 2001 CDC guidelines on surveillance evaluation to assess the systems usefulness, representativeness, timeliness, stability and acceptability. A retrospective record review of the measles case-based surveillance data from 2010– 2012 was carried out to assess data quality and representativeness. We calculated the annualized detection rate of measles and non-measles febrile rash, proportion of available results, proportion of Districts (LGAs) that investigated at least one case with blood, proportion of cases that were IgM positive and the incidence of measles. We compared the results with WHO (2004) recommended performance indicators to determine the quality and effectiveness of measles surveillance system. Results According to the Stake holders, the case-based surveillance system is useful and acceptable. Median interval between specimen collection and release of result was 38  days (Range: 16 – 109) in 2011, 11 days (Range: 1 – 105) in 2012. The best median turnaround time of 7days (1 – 25) was recorded in 2010. The annualized detection rate of measles rash in 2011 was 1.0 (target: ≥2), in 2012 it was 1.4 (target: ≥2). The annualized detection rate of non-measles febrile rash in 2011 was 0.6 (target: ≥2) while it was 0.8 (target: ≥2) in 2012. Case definitions are simple and understood by all the operators. We found a progressive decline in  timeliness and data quality in the years under review.ConclusionThis evaluation showed that the surveillance system was still useful. Also, the efficiency and effectiveness of the laboratory component as captured by the “median interval between specimen collection and the release of results improved in 2010 and 2012 compared to 2011. However, there was a progressive decline in the timeliness and completeness of weekly reports in the years under review.Keywords:  Measles; Case-based; Surveillance; Evaluation; Nigeria