affiliation not provided to SSRN, University of Basel - Swiss Tropical and Public Health Institute, University of Basel - Swiss Tropical and Public Health Institute, University of Basel - Swiss Tropical and Public Health Institute, University of Basel - Swiss Tropical and Public Health Institute, affiliation not provided to SSRN, University of Basel - Swiss Tropical and Public Health Institute, affiliation not provided to SSRN, University of Basel - Swiss Tropical and Public Health Institute and University of Cape Town (UCT)