Reactivity of blood samples spotted onto filter papers in the WST-8 method for screening of G6PD deficiency.

� ��������������������������������������������������������������������������������������������������������-����������������� � �������������������������������������������������������� ������������������������������������������������������������-������������Defi ciency of glucose‑6‑phosphate dehydrogenase (G6PD causes acute hemolytic anemia triggered by oxidative drugs such as primaquine. It is therefore essential in malaria‑endemic areas for malaria patients to be confi rmed for their G6PD activity before taking primaquine. The WST‑8 method a newly established screening method for G6PD defi ciency has been demonstrated to be suitable for fi eld conditions particularly for on‑site malaria surveys. Here we report a laboratory evaluation by this method of the reactivity of blood‑spotted fi lters. A time‑course experiment was conducted to evaluate the reactivity of blood samples spotted onto 4 types of fi lter paper Whatman 31ET Chr (ET 3MM Chr (3MM P81 and Advantec No. 2 (AD2. The rank of the relative reaction intensity was ET > 3MM = AD2 > P81. Blood‑spotted fi lters stored at 4C gradually decreased G6PD reactivity with the passage of storage time whereas those stored at room temperature rapidly reduced their reactivity. Unexpectedly saponin supplementation reduced the reactivity of blood‑spotted fi lters. In conclusion 1 ET is the most suitable fi lter for the WST‑8 method ; 2 blood‑spotted fi lters stored in cold condition can be assayed within 14 days or those stored at room temperature should be tested within 3 days ; and 3 reaction mixtures should not contain saponin.