Mass screening tools for glucose-6-phosphate dehydrogenase deficiency: validation of the WST8/1 -methoxy-PMS enzymatic assay in a highly malaria-endemic area in Uganda by De Niz Mariana, Eziefula Alice C, Maiteki-Sebuguzi Catherine, Gonahasa Sam, DiLiberto Deborah, Tumwebaze Patrick, Staedke Sarah G, Drakeley Chris J