Sub-national stratification of malaria risk in mainland Tanzania: a simplified assembly of survey and routine data by Thawer, SG, Chacky, F, Runge, M, Reaves, E, Mandike, R, Lazaro, S, Mkude, S, Rumisha, SF, Kumalija, C, Lengeler, C, Mohamed, A, Pothin, E, Snow, RW, Molteni, F