Trends of measles in Namibia, a secondary data analysis: 2012-2015

Abstract

Introduction: measles is one of the vaccines preventable diseases (VPD) which are currently under surveillance in Namibia, due to the high incidence of cases reported worldwide rendering it a public health concern. We determined the trends of measles in Namibia and described the data in terms of person, place and time. Methods: we reviewed secondary data from the National Health Information System database on Measles from 2012-2016. The surveillance system detects cases based on the standard case definition for measles which includes any person, suspected by clinician having measles infection, or, any person with fever and maculopapular rash and cough, coryza or conjunctivitis. Diagnosis is confirmed by positive measles IgM laboratory result, or a suspected case epi linked to a confirmed case. We analyzed the data using Epi info version 7.2, frequencies were derived and data was described in terms of person, place and time. Results: during the 5-year period, a total of 1846 (26.86%) measles cases were confirmed by either IgM positive laboratory result or epidemiological link, out of 6873 reported cases. The trends of positive measles cases were 82 (17.26%) in 2012, 467 (35.43%) in 2013, 1069 (44.91%) in 2014, 196 (8.39%) in 2015 and 32 (8.79%) in 2016 (p-value < 0.001). Over the 5 years, the majority of cases were detected among children aged 0-10 years, 784 (42.47%). The mean age being 13.7 years, with a SD of 11.8 years. The median age of 9 years and mode of 1 year. The ratio of affected males to females was 1.05:1. Conclusion: only 26.86% of reported cases were found to be positive for measles, this is attributed to the sensitivity of the surveillance system. During the years 2013 and 2014 Namibia experienced measles outbreaks, which was detected by the surveillance system. Children under the age of 10 were most affected age group over the 5-year period, which raises concerns about vaccine efficacy and immunization coverage in that population group. We recommend a study on vaccine efficacy and immunization coverage.