Serosurvey of rubella in five blocks of Tamil Nadu

Rubella, normally a mild, self-limiting disease characterized by rash, fever and lymphadenopathy, is a vaccine preventable disease. It carries little morbidity and apparently only minor complications in children. Infection during early pregnancy may lead to congenital rubella infection. Presence of rubella specific IgG in an unvaccinated population is a long term marker of previous rubella infection, which helps to assess the immune status of that population. Though many seroprevalence studies on rebella have been reported earlier from India, no study has been conducted in recent years. We undertook this study in 2003 in five blocks identified by the Integrated Child Development Scheme (ICDS), in the five districts of Tamil Nadu to assess the immune status to rubella in two age groups (1-5 yr boys and girls and 10-16 yr adolescent girls) before vaccination and draw strategies for future vaccination programme.

A total of 300 blood samples were collected by vein puncture from girls and boys of 1-5 yr age and adolescent girls of 10-16 yr age. Samples were tested for the presence of rubella specific IgG antibody by ELISA.

Of the 300 samples tested, 145 (48.3%) were negative for rubella IgG antibodies. The seronegativity was 82.2 per cent in 1-5 yr and 13.5 per cent in the 10-16 yr age groups, the difference was statistically significant (P<0.001).

Large percentage of children, 82.2 per cent in the 1-5 yr age group and 13.5 per cent in 10-16 yr population were susceptible to rubella infection highlighting the fact that there was a risk of congenital rubella syndrome. There is a need to implement routine measles, mumps, rubella (MMR) immunization programme for under five children and mass scale one time immunization with monovalent rubella vaccine for adolescent girls.