Impact of a Nationwide Measles Immunization Campaign and Routine Immunization in Nigeria, 2006-2010: A Critical Review of South-South, Nigeria

Background: Measles remains a serious problem of infancy and childhood in the developing world, despite the availability of vaccine. Increasing urbanization is changing patterns of endemicity. Objective: This paper critically examines the epidemiological impact of this nationwide measles immunization campaign and routine immunization, while taking into account any changes in surveillance performance. Methods: Blood samples were obtained from 4159 client at the surveillance focal sites scattered across the 123 district (LGAs) and were tested for measles specific immunoglobulin M (IgM). Five (5) ml of blood was collected from each subject into plain sterile bottle following informed consent. Blood samples were centrifuged and sera were separated and stored at -20oC until used. Samples were analyzed in batches for measles specific IgM using commercial ELISA (MV-ELISA) (Enzygnost; Behring Diagnostics, Marburg, Germany) in accordance with the manufacturer’s instructions. Tests were read on a pre-programmed spectrophotometer Quantum II, wavelength 450/630nm, manufactured by Abbott. Results: In total, 465 (11.2%) tested positive for measles specific IgM antibodies. Of these, 1962 were male and 2197 were female. The highest number of IgM positive cases was found in those less than 5 years (79.8%), while those aged 5-15 years, and 15 years and above recorded 17.2% and 3.0% respectively. The distribution of measles burden between urban and rural setting indicates that urban dwellers 53.8% were more susceptible to measles than rural dwellers (46.2%), this relationship was established as statistically significant with (p< 0.0001) and odds ratio was also high 1.669 (95% CI 1.375-2.025). A high significance of association between development of measles and vaccination status of subjects is also observed in this study (p < 0.0001), while odds ratio was also observed to be high 6.144 (95% CI 4.977-7.511). Conclusions: Improved understanding of measles epidemiology and risk factors are prerequisites for effective control. Possible strategies should include vertical vaccination efforts in addition to routine programmes.