The repellent group comprised 1,952.8 person-years with 60.45 ( 95 % C.I 48.30-72 .60 ) cases/1 ,000 person-years , demonstrating a non-significant 11.44 % reduction in malaria incidence rate in this group , ( Wilcoxon rank sum z = 0.529 , p = 0.596 ) .