Analysis of the Wuchereria bancrofti population in the people of American Samoa.

Recent interest in mathematical descriptions of the epidemiology of helminth parasites has prompted several attempts to obtain quantitative estimates of reproduction and survival at all stages in their life-histories. The availability of microfilarial counts, repeated on many people over 4(1/2) years, suggested that these estimates could be made for Wuchereria bancrofti. Important values that were calculated are the duration of patency for single infections (2(1/2) years), the maximum density of microfilariae achieved by 1 female (70/60 mm(3) of peripheral blood), the average output of larvae by a female during her lifetime (1.32x10(7)), the death rate of mated females (0.02-0.05 per month), the average load of reproducing female worms per blood-positive person (6.91 for men, 6.07 for women, 2.93 for children), and the average total load of worms in infected people (11.18 for men, 7.70 for women, 4.02 for children).The implications of the approach taken are important from the standpoints of epidemiology and control. The construction of a complete ecological life-table for the parasite is a distinct possibility. Life-tables from several areas differing in transmission rates should make it possible to predict the critical density of hosts, below which the parasite population should die out spontaneously.