An Outbreak of Measles among adolescents in a Health Care Setting, Bangalore, Karnataka, India

Abstract

Background: Despite high immunization coverage, outbreaks of measles do occur, but occurrence
of measles outbreak among adolescents in a health care institution setting in India, is rather unusual
or unreported. Methods: On the 21st November 2013, cases of suspected measles among the students
were reported at St. John’s Medical College, Bangalore. The preliminary investigation using the
epidemiological case sheet identified seven suspected cases of measles. This led to a detailed
investigation for a suspected outbreak at the campus. The outbreak was notified to the government
authority. A measles outbreak investigation case sheet was distributed among the students and a door
to door survey was carried out. The laboratory confirmation of suspected measles cases was done at
the National Institute of Virology, Bangalore by IgM test for measles specific antibodies, viral culture
and RT PCR. Results: The outbreak occurred during the months of November and December 2013.
A total of 13 confirmed cases of measles were identified with an overall attack rate of 2%. Five cases
were confirmed by IgM test for measles antibodies, besides virus isolation and RT PCR was positive
for two cases. More than half (54%) of the suspected cases were vaccinated for measles and the rest
were unvaccinated (23%) or had an unknown vaccination status (23%). There were no complications or
deaths due to measles. Conclusion: An outbreak of measles among a group of adolescents in a health
care institutional setting who were mostly vaccinated raises a concern about the vaccine effectiveness
and the duration of vaccine efficacy after immunization. Along with improving the immunization
coverage of two doses of measles vaccine, research is needed to determine the most-effective timing of
delivering the second routine dose to bring down the susceptible population.