Sero-epidemiology of rubella in Imo State of Nigeria.

931 serum samples collected at random from healthy subjects in the four health zones of Imo State were analysed for the presence of rubella haemagglutination inhibition antibodies. Rubella antibodies were present in 625 of the samples giving a prevalence of 66.6%. There was a gradual increase in the prevalence of these antibodies with increase in age except in the age group 10 to 19 years which had a high prevalence of 80 to 90%. The distribution of antibodies appeared to be influenced by type of settlement. Okigwe and Umuahia health zones, in which settlements are close together had significantly higher numbers of seropositive individuals than Owerri and Aba zones, in which communities are widely spread. Immunity to the virus was influenced by socio-economic factors. The prevalence of antibodies to the virus was greater in individuals of low socio-economic status than those of high socio-economic status. The sex of the individual was also a factor in the distribution of antibodies to rubella, more females than males having antibodies. There was no difference between urban and rural populations in the prevalence of antibody to rubella.