Objective To analyze the trend of chickenpox outbreak in Minhang District, Shanghai from 2009 to 2011, and to provide basis for developing chickenpox control and prevention measures.
Methods Data about chickenpox outbreak from 2009 to 2011 in Minhang Distrct were analyzed using descriptive epidemiological methods.
Results A total of 69 chickenpox outbreaks involving 681 cases occurred in Minhang District from 2009 to 2011. All outbreak spots were educational institutions, in which the outbreaks occurred in primary schools accounted for 65.64% of total outbreaks. The outbreak spots covered 120 098 students and the attack rate was 0.57%. An uprising trend of chickenpox was suggested. Two incidence peaks were identified: between March and May and between October and December in each selected year. The patients aged 5-14 years old accounted for 80.76% of all the cases. The ratio of male to female was 1.65:1. Regional variations in the chickenpox outbreaks were found, and more outbreaks occurred in the towns(neighborhoods)with more centralized schools. The breakthrough varicella cases accounted for 37.15% of all the cases. Nearly all(95.41%)of the intervals between vaccination and boarding ranged from 3 to 10 years, and most of which was from 5 to 7 years. The median interval between chickenpox outbreak reporting and the first onset was 8 days, and the maximum was 35 days.
Conclution The severe chickenpox outbreaks indicate that the school campuses are the focus of chichenpox related disease control strategy. Effective measures should be adopted for chickenpox prevention and control.
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