Diethylcarbamazine induces loss of microfilarial sheath of Wuchereria bancrofti

Light microscopy analyses of microfilariae of Wuchereria bancrofti treated with DEC revealed a striking loss of the microfilarial sheath. However, no effect was observed on microfilariae of Litomosoides chagasfilhoi treated with DEC. For quantitative analyses microfilariae of W. bancrofti were processed for SEM. Controls, which have not received DEC, had 29.8% of exsheathed microfilariae. Conversely, the number of exsheathed microfilariae increased as increased DEC concentrations: 5 μg/ml (75.9%), 10 μg/ml (80.1%), and 50 μg/ml (87.7%). After DEC treatment some of sheathed microfilariae showed a wrinkled surface, and in some microfilariae, sheaths were observed being liberated almost intact from the larvae surface. But, frequently residues of the lost sheath over the surface were also observed. No damage was observed in the microfilariae cuticle. The present work shows quantitative data on the loss of the microfilarial sheath of W. bancrofti after treatment with DEC. Since no loss of microfilarial sheath was observed in microfilariae of L. chagasfilhoi submitted to the same conditions, DEC may present different mechanisms of action for distinct filarial species.