Case incidence

Country estimates [as opposed to National Malaria Programme (NMP) and health management information system (HMIS) reports of cases and deaths, which in most countries under-state population-level burdens] were obtained from WHO’s Global Malaria Programme, for malaria case incidence (comprising uncomplicated and severe cases) and malaria-attributable deaths [1].

For most sub-Saharan African countries with stable falciparum malaria, WHO’s case and death estimates were based on an epidemiological model that projects case incidence from parasite prevalence measured through household surveys [2]. For 12 mostly lower-endemic countries, WHO estimates are based on NMP-reported clinical cases, with adjustment for (public) clinic coverage and reporting completeness, which sometimes resulted in case incidence trends over time that were at variance with those estimated by MAP (see below), and/or with WHO’s mortality trend estimates (giving fluctuating or eccentric case fatality rates). To avoid inconsistencies within Spectrum’s display of historic (pre-projection) burden trends for these 12 countries, Spectrum took WHO-based 2015 case incidence estimate and derived numbers and rates for 2000–2014 by applying the historic trend in case incidence from MAP, assuming either a same fixed difference in annual case numbers over 2000–2014 as in 2015, or a proportional scaling (Additional file 1).

WHO’s all-age-aggregated national case numbers were allocated across three age groups and Admin1 units, using annual age- and Admin1-specific case incidence estimates from MAP, who combined a spatial–temporal statistical description of PfPR (see below) with a statistical model of the PfPR-case incidence relationship, fitted to simulations from OpenMalaria and two other transmission models and accounting for local history of exposure and treatment coverage [18].