Cholera epidemiology in Mozambique using national surveillance data.

Background: Mozambique has experienced cholera for several decades. This study was undertaken to evaluate epidemiologic patterns to assist in guiding public health interventions.
Methods: We evaluated district-level Ministry of Health data for 123 consecutive weeks starting 1 January 2009. Cholera cases reported to the national level were based on clinical suspicion rather than microbiological confirmation. Time and space analyses with mapping and spatial statistics were undertaken.
Results: During 2009-2011, Mozambique identified 220 deaths among the 25 431 reported suspected cholera cases (case fatality ratio [CFR], 0.87%). There were 108 outbreaks that occurred in 73 (50%) of Mozambique's 145 districts. Five distinct spatial clusters were identified involving inland and coastal as well as rural and urban populations. Among 78 outbreaks whose duration was known, average duration was 7.2 weeks (median, 6; range, 1-25). During weeks 1-3, 4-6, 7-9, and ≥ 10 after an outbreak, CFRs were 1.6%, 0.66%, 0.33%, and 0.25%, respectively. During 2010, districts that experienced an outbreak during 2009 had a CFR of 0.2% compared with 4.3% among other districts.
Discussion: Mozambique continues to experience widespread cholera outbreaks of short duration involving distinct spatial clusters. These findings will influence choice of public health strategies.