The following points are based upon microfilarial counts of the blood of two patients parasitized with Wuchereria bancrofti.
1.Microfilariae were present at all hours of the day and night regardless of whether or not the parasitized individuals were awake or asleep.
2.In these two cases peak counts over 26 hour periods were diurnal, the peaks occurring between noon and 8:00 p.m.
3.Conversely, the lowest densities were nocturnal, occurring between midnight and 8:00 a.m.
4.The ratio of the mean high and low daily counts in both patients was low, being 3.4 in the case of patient A and 2.3 in the case of patient B.
5.In patient A the count over a seven and one-half month period showed some increase in numbers of microfilarise in spite of drug therapy with stibanose.
6.In patient B the peak density occurred 11 months after microfilariae were first demonstrated in the patient's blood. Three months and a half later the count showed a decrease, although the patient received no therapy.
7.It is suggested that the term “diurnal periodicity” might be found to be more appropriate than the terms “non-periodic” or “aperiodic” which appear widely in the literature.
S. A. Scientist, U. S. Public Health Service, National Institute of Health.
Major, P. C., U. S. A., Chief, Division of Parasitology, Army Medical School, Washington, D. C.
Biologist, Division of Parasitology, Army Medical School.