population treatments, as shown in Figure 1 (72). Of interest are: the drop in mean absolute eosinophil counts on Rongelap Atoll during broad-spectrum anthelminthic treatment with mebendazole, followed by resurgence during the post-treatment period; and the relatively stable eosinophilia on Utirik, de- spite ascaricidal treatment, which appears to correlate with temporal observa- tions on helminth prevalence on that atoll. T T TT | o = PYRANTEL PAMOATE (UTIRIK) * =MEBENDAZOLE (RONGELAP) | (per cu. mm.) MEAN ABSOLUTE EOSINOPHILIA 1 -3 LL 0 1 3 i 67 L 9 19 MONTHS Fig. D. 1. Peripheral eosinophilia in populations for intestinal parasites. treated Conclusions The results of the parasitic surveys undertaken during suppressive ef-~ forts on Rongelap Atoll from 1977 to 1979 and on Utirik Atoll from 1978 to 1979 have indicated the presence of those intestinal helminths expected in non-urban populations living in the tropical climate of the mid-Pacific, and, though with less complete documentation, also of the expected intestinal protozoa. The introduction of Ascaris lumbricoides onto Rongelap Atoll following the 1958 survey is well documented in this study. However, the extent of its success in becoming established, as well as its presence to the same extent on Utirik Atoll, suggest that its absence during the 1958 survey may have been partly anomalous, and may have resulted from the Rongelapese population's preceding three-year absence from their island. Certainly, the people are now very aware of the presence of roundworm. The extent to which diarrheal dis- ease may be attributed to endemic intestinal parasites is unclear, although a partial cause-and-effect relationship is quite probable with regard to the protozoal pathogens detected. On the other hand, the results of a recent re- port on shigellosis in the Marshall Islands (73) would suggest that bacterial species may also be involved in diarrhea on the outer atolls; considerable contact now occurs (albeit at infrequent intervals) between Rongelap, Utirik, Ebeye, and Majuro, on the latter two of which an outbreak of Shigella flexneri diarrheal illness was well documented. - 41+