Rubella Outbreak among Drivers in Vehicle Department, Bangkok, December 2010 – January 2011

Abstract

Background: On 17^th January 2011, Bureau of Epidemiology (BoE) was notified about 2 suspect rubella cases in vehicle department, Bangkok from Medical Sciences Center. An investigation was conducted during 19^th – 20^th January 2011 by Bangkok and BoE investigation team.
Methods: We interviewed cases, their colleagues and physicians who treated patients. We reviewed their serological results to rubella titer at Phramongkutklao hospital and collected blood, throat swab and sent to Department of Medical Sciences for rubella identification. A suspect case was defined as a person who worked in the vehicle department, had generalized erythematous rash during 1^st December 2010 to 31^st January 2011. A probable case was a suspect case with borderline IgM for rubella and a confirmed case was defined a case with positive IgM or positive cell isolation for rubella. Asymptomatic case was a person who had positive IgM for rubella without any symptom of rubella. We also conducted environmental survey in the vehicle department.
Results: There were 2 probable cases and 3 confirmed cases with a couple case had rubella genotype 2B. Only one asymptomatic case was found. All cases were male, median age was 29.5 years old (IQR 26-32). 5 cases worked in vehicle department and 1 case worked in cloth department. In vehicle department, their works divided to 2 shift, odd day and even day. 4 cases worked on odd day with attack rate (AR) was 3.3% and only 1 case worked on even day with AR=8.3%. They rested in the same crowded room with separated air condition and shared their beds was a suspect exposure. Mass MMR vaccination was implemented. Case isolation, big cleaning in vehicle department’s bed room and active surveillance for new cases was recommended.
Conclusions: This is an outbreak of rubella genotype 2B among drivers in vehicle department during December 2010 – January 2011. Among drivers who worked together on the odd day and shared crowded bed room with the first case was a high risk of rubella infection.