Attack rate and household secondary attack rate of acute conjunctivitis during an outbreak in South India: A community‑based survey.
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Date
2016-04
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Abstract
Introduction: Knowledge on epidemiology of the disease in the contemporary world will help to
develop appropriate strategies to curtail the transmission during an outbreak. This study was carried
out during an outbreak of conjunctivitis in selected areas of Puducherry, South India, to assess the attack
rate of conjunctivitis, identify factors associated with developing conjunctivitis and calculate household
secondary attack rate (HSAR) of conjunctivitis and its correlates. Methodology: During December 2014,
a community‑based survey was conducted in a selected urban and rural area in Puducherry, South India.
Simple random sampling was used to select primary sampling units and systematic sampling to select
households. All individuals in the selected households were studied. A questionnaire was used to
obtain data on sociodemographic characteristics, conjunctivitis during September–November, 2014,
and number of household contacts who developed conjunctivitis within 7 days of index case. The
attack rate and HSAR of conjunctivitis was expressed as percentage. Multivariate logistic regression
was used to find factors independently associated with developing conjunctivitis and also 100% HSAR.
Results: Of 3193 study participants from 772 households, 509 (15.9%, 95% confidence interval 14.7–17.2%)
had an attack of conjunctivitis during the reference period. Of the 772 households, 218 (28.2%) had at least
one case of conjunctivitis. Of 218 households, 33 (15.1%) households had 100% HSAR. Lower age, not
being unemployed, low socioeconomic status, and residing in rural area were independently associated
with developing conjunctivitis. Index case being male and living in a household with ≥5 members were
independently associated with 100% HSAR. Conclusion: In the outbreak under study, more than one‑fourth
of households had at least one case of conjunctivitis and about one in every six individuals had an attack
of conjunctivitis.
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Keywords
Attack rate, conjunctivitis, outbreak, secondary attack rate
Citation
Thekkur Pruthu, Reddy Mahendra M, Naik Bijaya Nanda, Subitha L, Kar Sitanshu Sekhar. Attack rate and household secondary attack rate of acute conjunctivitis during an outbreak in South India: A community‑based survey. Indian Journal of Ophthalmology. 2016 Apr; 64(4): 266-271.