Measles Outbreak among Male Prisoners in Maha Sarakham Province, Thailand, March - June 2013

Abstract

Background: On May 28^th, 2013 Maha Sarakham hospital’s staff notified a suspected measles case who referred from a provincial male prison. After verification, there were many cases that had fever and rash in the prison. The Surveillance and Rapid Response Team (SRRT) from Maha Sarakham provincial health offices, Mueang district, Chiang Yuen district, Office of disease prevention and control region 6th and Department of medical sciences jointed outbreak investigation during May 30^th – June 21^st, 2013. The objectives aimed to confirm the diagnosis and outbreak, to identify the risk factor of the outbreak and to implement control and prevention measures. We also evaluated the sensitivity and predictive positive value of Dried Blood Spots (DBS) collection compared to serum collection which tested by ELISA Measles IgM technique.
Methods: Descriptive and matched case-control studies were conducted. The randomized samples of 25 cases were enrolled and 75 controls were matched. Case definitions were divided into suspected, probable and confirmed. Data collection form was using ME2 standard form and modified questionnaire. We analyzed descriptive statistic, OR, 95%CI and multiple logistic regression analysis was done for identifying independent risk factor.
Results: Measles outbreak in Maha Salakham male prison is confirmed. Overall morbidity rate was 18.1/1000 population. There were 3 confirmed case (12%), 10 probable case (40%), 12 suspected case (48 %). Median age was 25 years, range 20 - 24 years. There were mild complication (5 cases) and no fatal case. The risk factors were share blankets (OR = 28.2, 95% CI 3.63- 220.01), close contact (OR = 5.5, 95% CI 1.75-17.28) and history of moving out of the prison 2 week before the illness began (OR = 4.0, 95% CI 1.14-14.7). Only share blanket reveled the strongest risk factor in the outbreak (ORadj = 24.8, 95% CI 2.79-219.83). Confirm diagnosis by DBS was high sensitivity (100%), specificity (100%) and positive predictive value (100%) with consensus was 96% when compared to serum. The viral culture was positive in one case and determined to be D8 genotype.
Conclusion: The outbreak was highly suspicious introduced from outside of the prison. There were affected to the prisoners who didn’t have measles immunity or the measles vaccine history was not clear. The important method to control outbreak was MMR vaccination all prisoners and staffs. And isolated measles case and health education to improve hygiene were implemented. We recommended to stopping sharing blanket and did not allow prisoner move to other prison during illness. New prisoner should be interview and vaccinate MMR before entry. Early reporting and rapid response is a crucial for successful outbreak control.