Pe. Simonsen et al., WUCHERERIA-BANCROFTI IN TANZANIA - MICROFILARIAL PERIODICITY AND EFFECT OF BLOOD-SAMPLING TIME ON MICROFILARIAL INTENSITIES, TM & IH. Tropical medicine & international health, 2(2), 1997, pp. 153-158
The circadian periodicity of Wuchereria bancrofti microfilarial (mf) i
ntensities in peripheral blood was analysed in a group of infected ind
ividuals from an endemic community in north-eastern Tanzania. The mf d
ensity was quantified at two-hourly intervals for 24 hours. A clear no
cturnal periodic pattern was observed. Mathematical analysis of the da
ta indicated a peak at 0152 h and a periodicity index of 117.5. A peri
odicity equation was developed describing the average relation between
mf intensity and hour of the day for the study area. Based on the obs
erved periodicity pattern, the effect of blood sampling before peak ti
me is discussed, and the importance of taking sampling time into consi
deration when analysing data from epidemiological studies is emphasize
d. A simple method is devised which can be used to adjust for the infl
uence of time on mf intensities, in studies where accurate information
on mf intensities is necessary, and where it is impossible to obtain
all samples at peak time.