Measles in Democratic Republic of Congo: an outbreak description from Katanga, 2010-2011

Background: The Democratic Republic of Congo experiences regular measles outbreaks. From September 2010, the number of suspected measles cases increased, especially in Katanga province, where Medecins sans Frontieres supported the Ministry of Health in responding to the outbreak by providing free treatment, reinforcing surveillance and implementing non-selective mass vaccination campaigns. Here, we describe the measles outbreak in Katanga province in 2010-2011 and the results of vaccine coverage surveys conducted after the mass campaigns. Methods: The surveillance system was strengthened in 28 of the 67 health zones of the province and we conducted seven vaccination coverage surveys in 2011. Results: The overall cumulative attack rate was 0.71% and the case fatality ratio was 1.40%. The attack rate was higher in children under 4 and decreased with age. This pattern was consistent across districts and time. The number of cases aged 10 years and older barely increased during the outbreak. Conclusions: Early investigation of the age distribution of cases is a key to understanding the epidemic, and should guide the vaccination of priority age groups.