Outbreak of Influenza (H1N1) amongst children in a residential school

Background

An outbreak of pandemic Influenza H1N1 occurred from 13 Feb to 20 Feb 2010 in a residential school at Belgaum, India.

Methods

On report of sudden increase in number of students reporting sick with symptoms suggestive of flu like illness, an investigation was launched to detect the source of infection and to control the spread of infection amongst those not affected. Six random samples of throat from the initial cluster were collected and RT-PCR was done to confirm the diagnosis. The outbreak in this institution was effectively controlled by standard preventive & control measures in the absence of vaccine.

Result

In a school of 335 children, 96 cases of Influenza like illness possibly resulting from pH1N1 (2009) were reported with an attack rate of 28.6%. Out of a total of 96 cases reported, 73 (76%) were hospitalized and 23 treated as outdoor patients. Serogroup A of Influenza H1N1 pandemic was identified to be the agent responsible for this outbreak as 06 random samples drawn from initial cluster tested positive on RT-PCR. A visit to an exhibition in the city was possibly the source of exposure amongst the children.

Conclusion

An outbreak of Influenza H1N1 infection amongst students in a residential public School was found to be linked to a visit to an exhibition following which the secondary transmission led to further occurrence of cases.