Application of Dried Blood Spots on Filter Paper for Detection of HIV Antibodies: Effect of Temperature and Duration of Storage

Background: Acquired immunodeficiecy syndrome (AIDS) is now adays a worldwide health problem affecting both the developed and developing countries. It has greater burden on the developing countries because of the increased cost of testing including specimen collection, transport, storage and laboratory examination. Moreover the present technique of collecting blood for diagnosis is associated with increased risk of infection, loss and contamination of specimen. This study aimed at evaluating the use of blood spot dried on filter paper (under different storage conditions) for detection of HIV antibodies in patient\'s serum as an alternative cheap and relatively safe method. Materials and methods: venous blood was collected from 100 known HIV infected patients and 50 healthy volunteers. Filter papesr (Whattman number 1) were soaked with the specimens, air-dried and then divided into 3 groups. Each group is containing a sample from each subject under study. The three groups were subjected to different storage conditions (room temperature, incubator at 37 o C and refrigerator at 4oC). PBS elutes from each group were tested for HIV antibodies using ELISA at regular intervals (48 hrs., 7,15, 30, 45, 60, 75, 90 and 105 days). Results: All the dried blood on filter paper remained positive for HIV antibodies for one month. Thereafter some of the specimens started to progressively show negative results. Specimens stored in the refrigerator were more stable for HIV antibodies than those kept at room temperature and the incubator. Discussion: In this study, the results of testing elutes of dried blood spots on filter paper for HIV antibodies were found to be 100% positive in concordance with those of testing serum samples. HIV antibodies were stable in all specimens for one month under the different storage conditions. Conclusion: dried blood spot on filter paper can remain positive for HIV antibodies for at least one month under different storage conditions. It can therefore be recommended as a cheap, simple and reliable technique for collection of blood for HIV testing under field surviellance as it does not require complex setting and instruments and moreover it eases transportation of specimen. Keywords: immunodeficiency syndrome (AIDS), storage, heparinized, ELISA.Sudan Journal of Medical Sciences Vol. 3 (2) 2008: pp. 147-15