MICROSCOPIC DIAGNOSIS OF BLOOD PARASITES FOLLOWING A CYTOCONCENTRATION TECHNIQUE

An isotonic fixative (formalin and thimerosal) solution, with a saponi n additive to lyse erythrocytes and platelets, has been developed. The formalin and thimerosal ensure good preservation of blood parasites. This fixative has led to the development of a new concentration techni que using cytocentrifugation (cytospin) in the search for Plasmodium s pp., Leishmania spp., and microfilariae, as well as leukocytes in whic h parasites or pigment may be present. The concentration of the parasi tes present in the sediment from 100 mu l of blood spread on a 6-mm di ameter circle results in good morphology that is well stained using th e usual Giemsa or Wright techniques. This new technique has the advant age of a relatively low cost and offers the possibility of isolating a nd identifying in the same sediment the main blood-stage parasites, wi th the exception of young trophozoites, of Plasmodium falciparum.