Isolation and concentration of microfilariae from peripheral blood of Wuchereria bancrofti infected patients by density gradient centrifugation.

A Ficoll-Hypaque gradient centrifugation technique was used for isolation and concentration of microfilariae from peripheral blood of 30 subjects with clinically and parasitologically diagnosed Wuchereria bancrofti infections. 86% of the microfilariae were found in the Ficoll-Hypaque layer. None were detected in the plasma, leucocyte layer or lower erythrocyte layer. 14% of microfilariae were identified on the top part of the erythrocyte layer. A 35 fold concentration and 88% quantitative recovery of parasites was achieved by conventional centrifugation of microfilariae-rich Ficoll-Hypaque layer. Following the centrifugation procedures, living motile microfilariae were separated. These results indicate that Ficoll-Hypaque centrifugation technique could be an effective method for the detection of low levels of microfilaraemia, and for obtaining relatively pure suspensions of living microfilariae for metabolic studies, production of antigen-rich excretory-secretory products and antigen analysis.