sampling in March 1978. Both immediate follow-up periods extended through September 1979, but a "final" long-term sampling follow-up is planned for November 1980, possibly as a prelude to institution of long-term parasite- suppressive efforts. The treatment plan for the two atolls, though not theoreticaily ideal, was based on logistical realities as to what would be attainable in the con- text of health surveys and physician visits. Following initial stool surveys, treatment with each agent was to be given at quarterly intervals to all inhabitants of the respective atolls except pregnant women and children aged <2 years. Follow-up surveys were to be conducted just before the third quarterly treatment and 9 months thereafter. On Rongelap the schedule was maintained, but ship damage caused schedule alterations during the eradication/suppression attempt on Utirik which resulted in some variation from the treatment/sampling plan. The actual schedules attained are shown in Table 1. Sampling (S) and treatment (T) schedules on Rongelap and Utirik Atolls, 1977-1979. January March June September -. s - s - - - : iHAteis March June September t 1979: January rrinmninis 1978: June September Utirik tAaade 1977: 1M EN Ronge lap ‘ Table 1. Ss - Sampling. To the extent that they were in any way reachable, all inhabitants of Rongelap Atoll were prevailed upon to submit stool specimens at each sampling period. In spite of strong fecal taboos, samples were obtained from at least 90% of the population by diligent follow-up of dispensed stool containers. Lo The larger population of Utirik (4300) precluded the possibility of total sampling during the limited survey period. Instead, a cohort of 20+% of the population was followed to the extent possible, and was used as an index of the population as a whole. If cohort members were not present on the is- land during a survey (away at school, on a visit, etc.), replacements were picked at random to fill out the three categories: adult males, adult fe- males, and children. Again, diligent follow-up of dispensed containers provided the requisite popirlation samples. Processing of Specimens. An aliquot of 0.5 to 1 g of each specimen returned each day was put into an individually identified l-dram vial ~- 37 -