Measles outbreak in Qassim, Saudi Arabia 2007: epidemiology and evaluation of outbreak response.

BACKGROUND Worldwide efforts for measles elimination are made possible due to the availability of a highly effective measles vaccine. In spite of highly vaccinated population, a measles outbreak occurred in Qassim province of Saudi Arabia, during January-August 2007. METHODS An outbreak investigation was conducted to describe the epidemiology of outbreak. An audit of performance of control measures taken by the Primary Health Care team was done according to World Health Organization standards. RESULTS Of 230 cases reported, more than one-third (37.8%) patients were 0-4 years of age. Children aged 6-11 months accounted for 51.7% cases amongst 0-4 years age group. The performance indicator targets of >or=80% for outbreak control measures were achieved regarding investigation of cases within 48 hours, and blood sample extraction within the optimal period. However, 66.8% cases reported within 48 hours of rash onset and only 16.4% of laboratory test results were received within 7 days of receipt of the specimen in laboratory. CONCLUSION This outbreak demonstrates the increased susceptibility of unvaccinated children aged 6-11 months. To prevent future outbreaks, community awareness, review of measles vaccination schedule, enhanced surveillance and measles 'catch-up' mass immunization campaign to interrupt chains of transmission, are required.