Rubella outbreak investigation, Gokwe North District, Midlands province, Zimbabwe, 2014 - a case control study

Abstract

Introduction: Rubella is a contagious disease, caused by rubella virus and transmitted via the  respiratory route. Rubella in pregnancy may cause Congenital Rubella Syndrome (CRS), characterized by multiple defects to the brain, heart, eyes and ears. Gokwe North experienced an increase in rubella cases from 6 cases (24 June 2014) to 374 cases (12 August 2014). The study was conducted to determine risk factors associated with contracting rubella.

Methods: A 1:1 unmatched case control study was conducted. A case was a child <15 years, resided in Gokwe North, with maculopapular rash and tested positive for rubella specific IgM or was linked  epidemiologically to a laboratory confirmed case. Blood was collected for laboratory diagnosis. An  interviewer administered questionnaire was used. Epi InfoTM was used to analyze data.

Results: Eighty eight cases and 88 controls were recruited, median age for cases was 7 years (Q1=4, Q3=8) and 6 years (Q1=3, Q3=9) for controls. Independent risk factors for contracting rubella were; classmate contact (AOR 9.44; (95% CI 4.29-20.77)) and having >3 children in a household (AOR 2.59; 95%CI (1.23-5.42)). Only 10.2% and 6.8% of the caregivers' cases and controls respectively, knew  rubella is spread through contact with an infected person (p=0.57). Majority of caregivers (97.8%) reported to the health facility within two days of onset of rash.

Conclusion: Outbreak was driven by contact at school and was spread into the community through  school children. Screening and isolation of the sick controlled the outbreak. Routine rubella vaccination could be considered to prevent similar outbreaks.

Key words: Rubella outbreak, risk factors, Gokwe North