example, approximately 60% of inhabitants of American Samoa and 40% of the population of Ponapeare reported to have serologic evidence of past infection with this virus (Wong, Purcell, and Rosen 1979). The clinical significance of the cellular immune response in hepatitis B infection is unclear (Hansonet al. 1984; Rustgiet al. 1984). In contrast to hepatitis A, serious late manifestations of disease (chronic active hepatitis, cirrhosis, and hepatocellular carcinoma) are not rare with hepatitis B. It has been suggested that Japanese atomic bombing survivors in the United States do not have a deficit in natural cell-mediated cytotoxicity (Bloom et al. 1983), but studies of the Radiation Effects Research Foundation have revealed an impaired response of lymphocytes to phytohemagglutinin in Japanese receiving >100 rads (Akiyamaet al. 1983). If the radiation-exposed Marshallese have an impaired immune mechanism, it is possible that they will be atincreased risk for serious hepatic sequelae if they acquire the infection. For this reason, a serological evaluation of radiation-exposed and unexposed Marshallese was performed in conjunction with the Hepatitis Branch, Division of ’ Viral Diseases, Centers for Disease Control, Atlanta, GA (Dr. Howard Fields and Dr. Stephen Hadler). . Analysis of the results of serologic testing of 314 Marshallese tested revealed that 91.8% gave serologic evidenceof past hepatitis B infection. The surveyed population included 98% of the Rongelap group, 82% of the Utirik group, 70% of the comparison population, and 46 younger persons. The last group, ranging in age from 10 to 28 years, was included to evaluate the agespecific prevalence of infection. A tabulation of the hepatitis experience of the different sub- groups is presented in Table 2. There was no difference in the prevalence of serologic evidence of hepatitis B infection among the three exposure groups. However,a significant group differencein the prevalence of hepatitis B surface antigen wasdetected, with the high-exposure Rongelap group having the lowest prevalence (X?= 8.17, df= 2, p< 0.02). This finding contrasts with that of the Radiation Effects Research Foundation, which indicated that the Japanese atomic bombing survivors who received > 100 rads had a significantly higher prevalenceof hepatitis B surface antigen ae rms uMuUuL a J than the low-dose groups (3.4% vs 2.0%) (Kato et al. 1983). The reasonfor the relative infrequency of hepatitis B surface antigenemia among the exposed Rongelap group (2 of 61 personstested) is not known. However,it is morelikely related to local factors rather than to radiation dose becausethe prevalenceof this hepatitis B marker among the unexposed comparison population was notsignificantly different from that of the Rongelap exposed (X?= 1.93, df=1, p> 0.10). Serological evidence of delta agent was not found in anyof the persons tested. Delta agent is a co-infecting virus which can affect the host response to hepatitis B. Since the frequency of serious chronic liver disease can be much greater in delta antigen-positive individuals, its absence in the Marshallese is reassuring from thepublic health perspective. Tuberculin and Candida - Sensitivity Impaired cellular immunity increasesthe risk of manytypes of infection. A survey of skin test responsiveness to mycobacteria and Candida was therefore undertaken to determine whether the exposed Marshallese reacted appropriately to these antigens. Another reasonfor the choice of M. tuberculosis testing is the increasing prevalenceof tuberculosis in many parts of the world, including Micronesia. Mostpersons were evaluated in March 1983. Screening was performed with the Mantoux tuberculin test, where 0.1 ml of PPD containing 5 TU was injected intracutaneously into the forearm in a manner recommended by the American Thoracic Society. A dosage of 0.1 ml of Candida antigen was injected into the opposite arm to test for anergy. After 48 to 72 hours, the amountof induration was measured, with 10 mm or more of induration being considered a positive test. Most individuals with a positive test had a chest x ray taken. Exceptions included those persons who were known,either by personal] history or from the medical program records, to have had a positive PPD in earlier years. A total of 323 PPD tests were applied and read in adults (those = 15 years of age). Of those tested, 147 had a positive test, for a prevalence of 45.5%. One hundred and ten persons received a chest x ray; none revealed evidence of tuber-