Measles outbreak in the adolescent population - Matter of concern?

Introduction: Measles is a disease predominantly seen in young children and infants. It is an unusual occurrence of the disease in the adolescent population warranting an investigation. This would help understand the possible cause-effect relation, changing epidemiology of the disease and immunity gaps to initiate targeted interventional strategies. Aim: To determine the time, place and person distribution of an outbreak and calculate the attack rates and vaccine efficacy. Materials and Methods: Investigation of an outbreak was conducted by an emergency rapid response team following the report of a case of measles on 18^th November 2013, in and around the campus of the study university in search of suspects and undetected cases. W.H.O developed standard outbreak investigation formats, were used for obtaining the data. The subjects were chosen by purposive sampling. All the contacts of the cases were approached along with a house to house survey in the surrounding residential area for active case finding. Measles was clinically diagnosed based on the standard case definition of measles as per the WHO guidelines and confirmed through measurement of measles specific IgM antibody levels in the serum of suspected/clinically confirmed cases. Results: The outbreak lasted for duration of six weeks during which a total of 20 laboratory confirmed cases were found. Most of the cases were in the age group of 21-25 years. The overall attack rate was 3.5% and vaccine efficacy was calculated to be 75%. Conclusion: There is an epidemiological shift in the age of occurrence of measles in the region among students coming from various regions of the country staying predominantly in hostels.