INVESTIGATION OF MEASLES OUTBREAK IN FARASH TOWN, ISLAMABAD, PAKISTAN. A CASE CONTROL STUDY
Keywords:Measles, routine immunization, risk factors, misconception
Background: On April 14, 2017, two measles cases were reported by local health practitioner from Farash Town. A team of FELTP fellows were deputed to investigate the outbreak.
Methods: Outbreak investigation was carried out from April 18 to 30th April, 2017. Active case finding was conducted through house-to-house survey.Case was defined as "onset of maculopapular rash with fever and presence of any of the sign/symptoms like coryza, conjunctivitis and cough in a resident of Farash Town from March 25, 2017 to April 30, 2017". Community-based age and sex-matched controls were selected.Vaccine coverage survey was conducted in cluster of 450 houses.Frequencies were calculated, attack rates computed and vaccine efficacy was determined. Blood samples of 03 suspected cases were sent to Public Health Laboratories at NIH Islamabad for confirmation.
Results: A total of 15 cases were identified.Mean age was 44.5 months (range 05-120 months). The cases were predominantly male n=9(60%). Overall attack rate was 1.15% and most severely affected age group was 24-36 months (n=4, AR=10.81%) followed by 12-24 months (n=3, AR=8.10%). Diarrhea developed in n=12 (80%) and pneumonia developed in n=2 (13.3%). Vaccine efficacy was calculated to be 60%. The most significant reason for non-vaccination was misconception about vaccination (OR: 26 c.0, CI: 4.9-116.1). All blood samples were positive for measles-specific IgM on ELISA.
Conclusion: Low immunization status was the most probable cause of outbreak. The results were communicated to district health authorities for mass vaccination. Health awareness session was conducted for all households.No new case was reported during two weeks follow-up.