Age, spatial and temporal variations in hospital admissions with malaria in Kilifi County, Kenya: A 25 year longitudinal observational study by Bejon, P, Mogeni, P, Williams, T, Fegan, G, Nyundo, C, Bauni, E, Mwai, K, Omedo, I, Njuguna, P, Newton, C, Osier, F, Berkley, J, Hammitt, L, Lowe, B, Mwanbingu, G, Awuondo, K, Mturi, N, Peshu, N, Snow, R, Noor, A, Marsh, K