The periodicity of the microfilaria of wuchereria bancrofti. Preliminary report of some injection experiments

Abstract
Summary 1. A series of experiments is reported in which blood containing microfilariae was injected into non-filarial human subjects. 2. A method of blood examination for microfilaria is described. 3. Microfilariae were found to have great difficulty in passing through the peripheral capillaries. 4. Microfilariae are less active in day blood than in night blood. It is suggested that because of this, they are not able to work their way through the capillaries in the daytime, hence the mechanism of nocturnal periodicity. 5. In one subject the injected microfilariae lived 14 days and observed typical nocturnal periodicity. 6. In another subject who showed clinical signs of filariasis, the injected microfilariae (which were injected into the brachial artery) never passed through the peripheral capillaries. This suggests an acquired resistance to the parasites, and that in an immune patient the microfilariae are stopped in the capillaries and perish there. 7. In a subject showing elephantiasis the microfilariae survived only 2 days.