Wormy persons: contributions to the nature and patterns of overdispersion with Ascaris lumbricoides, Ancylosotma duodenale, Necator americanus and Trichuris trichiura.

The dominant intestinal helminths in the Iranian villages of Kargar Malleh (hookworms), Bandar Abbas (hookworms) and Jazin (Ascaris lumbricoides and Trichuris trichiura), were recorded with their frequency distributions, in 80, 40 and 111 villagers, respectively in 1977-78. Anthelminthics were then used to remove all intestinal stages which were identified and counted. Analyses showed clumped or over-dispersed patterns in all cases. Each community contained 'wormy persons', 1 to 3% of the individuals carried 11, 16, 30, 38 or 84% of all the worms collected. 'Wormy persons' could only be identified for one parasite, thus those with the highest infestations of one species were not prone to higher infestation with another. In Jazin, 111 persons with measured initial worm burdens of A. lumbricoides, T. trichiura and Trichostrongylus spp. were followed without further therapy or change in habits for up to 12 months during re-infection. There was no significant correlation between those persons with high initial worm burdens and those with high burdens after 12 months. The public health significance of these findings is discussed.