An improved method for thick film preparation using saponin as a lysing agent.

Thick film examination for malaria is often hampered by the presence of cellular debris obscuring parasites. This is a major problem for diagnostic laboratories that do not have a high exposure to material identification. Films that are relatively free of cellular debris, allowing easier identification of parasites are an obvious advantage. Saponin has been used by researchers to liberate malarial parasites for harvesting from infected erythrocytes. It has also been used for thick film preparations for diagnosis, but has not gained widespread acceptance, possibly due to the persistence of cellular debris inherent in the technique. In the present study the saponin method for thick film examination has been modified by the inclusion of a centrifugation step to remove cellular debris. Thick films were run in parallel with films made using the standard Fields stain technique and the original saponin. Results indicate that the modified saponin technique provides superior preparations free of cellular debris.