Seroprevalence of measles-specific IgM and IgG antibodies among children (0-12 years) with measles-like symptoms: a hospital-based cross-sectional study in Northeast Nigeria.

backgroundNigeria has one of the highest measles burdens and the lowest vaccination coverage worldwide. The WHO AFRO region, including Nigeria, is currently working towards a revised target of eliminating measles by 2030. Nigeria's strategy includes improving MCV1 coverage at 9 months, supplemental immunization for children aged 9-59 months, and intensified case-based surveillance. Recently, MCV2 was introduced and is being piloted. Achieving at least 95% coverage with MCV2 at 15 months is essential for herd immunity. Despite these efforts, measles outbreaks persist, worsened by armed conflicts and the COVID-19 pandemic in Northeast Nigeria which disrupts health infrastructures and ultimately affects immunization activities. This study evaluates serological patterns and confirms measles infection among symptomatic children attending healthcare facilities in Northeast Nigeria. By integrating serology with socio-demographic and clinical risk factors, we seek to evaluate the serological profile and identify proportion of susceptible individuals among symptomatic children in some selected clinical settings in Northeast Nigeria.

methodsChildren with clinically suspected measles cases were recruited from selected primary healthcare centres (PHC) in Yobe, Borno and Adamawa between November 2022-July 2023. The study analysed serum samples for measles-specific IgM antibodies (n = 558) and measles-specific IgG antibodies (n = 372). IgM antibodies were determined using the EUROIMMUN measles virus IgM ELISA kit, and IgG antibodies were determined using the Calbiotech measles IgG kit. Odds Ratio (OR) and 95% Confidence Intervals (CI) were calculated from 2 × 2 tables using a Univariate Logistic Regression model. The association between measles and socio-demographic and risk factors was analysed using chi-square. Statistical significance was set at P ≤ 0.05.

resultsIn this study, seroprevalence was defined by the presence of IgM to indicate recent infection and IgG to indicate past exposure or immunity. The results showed a seroprevalence of 29.2% for measles IgM and 32.8% for measles IgG. Measles IgM and IgG antibodies were detected more among males compared to females, with a seroprevalence of 30.6% and 33.3% respectively. No significant association was observed between sex and Measles virus seropositivity for either IgM or IgG (P > 0.05). Although the odds ratio for males was 1.23, the 95% confidence interval (0.82-1.82) indicated that this difference was not statistically significant. The highest IgM and IgG antibodies were observed amongst children aged 1-3 years with a prevalence of 40.8% and 46.5% respectively. Vaccination was associated with a significant reduction in the odds of measles infection (OR 0.30; 95% CI, 0.20-0.44; P ≤ 0.005). LIMITATIONS: This study is limited by potential selection and recall biases. By focusing exclusively on children presenting with measles-like symptoms, the findings are not representative of the general paediatric population. Furthermore, reliance on parental recall for vaccination history introduces a high likelihood of information bias.

conclusionOur study identifies a high frequency of measles seropositivity among symptomatic children in selected healthcare facilities in Adamawa, Borno and Yobe states. While this study highlights a high prevalence of non-vaccination among symptomatic children, further research should focus on the need for localised investigation into immunization history in symptomatic cases. CLINICAL TRIAL NUMBER: Not applicable.