A total of 2,574 residents in Yaeyama District of Okinawa, Japan, were investigated using real time ultrasonography to determine the real prevalence of fatty liver in the general population and to define its associated factors. Overall prevalence of fatty liver was 14.0%. Prevalence of fatty liver in persons under 19 years old was only 1.2%, and increased with age to a maximumin persons 40-49 years of age and then decreased. For persons over 20 years old, obesity index and serum levels of triglyceride and total cholesterol were measured, and alcohol consumption was asked. Prevalence of fatty liver was significantly higher in drinkers than non-drinkers (p <0.01), and increased with alcohol consumption. Furthermore, in persons not suffering from obesity prevalence of fatty liver was significantly higher in drinkers than in non-drinkers (p < 0.001). The results of logistic regression analysis indicated that obesity and elevated serum triglyceride level in both sexes, and alcohol in males were significant predictors of fatty liver. In conclusion, prevalence of fatty liver increased with age to a maximumin persons 40-49 years of age and overall was 14.0%. Obesity was the strongest associated factor in both sexes and in males alcohol was also a strong factor.

In an investigation of the mode of transmission of adult T cell leukemia virus (ATLV) in family settings, 275 male and 444 female subjects positive for antibody to ATLV-associated antigen (anti-ATLA) were studied. Their children were surveyed for anti-ATLA status. None of the 82 children of a positive father and a negative mother were positive for anti-ATLA. In contrast, the antibody prevalence among children with a positive mother and a positive or negative father was 27.9% and 19.9%, respectively. Of 39 parents who had one or more anti-ATLA-positive children less than 20 years old, 56.3% of the fathers and 97.1% of the mothers were anti-ATLA positive. Algorithm computation showed the possibility of ATLV transmission from husband to wife to be 60.8% and from wife to husband to be 0.4% over a 10-year period. These data suggest that ATLV is transmitted from mother to child and from husband to wife in family settings.

A total of 2,584 healthy residents in the Yaeyama District of Okinawa, Japan, were investigated in 1984 to determine the prevalence of gallstone disease and its associated factors. Diagnosis of gallstone disease was assessed by real-time ultrasonography. For participants over 20 years of age, obesity index and serum levels of total cholesterol and triglycerides were measured. Overall prevalence of gallstone disease was 3.2%. Prevalence increased with age from 0% under 19 years of age to 11.4% over 70 years of age and was higher in females (4.0%) than in males (2.5%). The results of the logistic regression analysis indicated that age and fatty liver were significant predictors of gallstone disease. The results of the automatic interaction detector analysis indicated that age and fatty liver were strong factors associated with gallstone disease and that prevalence was highest in females over age 50 with fatty liver.

We examined the effects of various factors, including duration of breastfeeding, the status of mother's anti-p40tax, and titre of mother's anti-human T cell lymphototropic virus type-I (HTLV-I) on mother to child transmission of HTLV-I in 76 HTLV-I carrier mothers and 175 of their children. The overall prevalence of anti-HTLV-I among children was 16.0%. The prevalence of anti-HTLV-I among children breastfed for over 3 months was significantly higher (27.6%) than that of those breastfed for under 3 months (5.1%; P = 0.012). Of the 78 bottle-fed children, 10 (12.8%) were positive for anti-HTLV-I. In the children breastfed for over 3 months, the prevalence of anti-HTLV-I among 37 children of anti-p40tax positive mothers was 37.8% and that of 21 children of anti-p40tax negative mothers was 9.5%, a significant difference (P = 0.044). These data suggest that about 13% of bottle-fed children born to carrier mothers are infected with HTLV-I by routes other than breast milk, and that the mother's anti-p40tax can serve as a marker of infectivity of HTLV-I in the case of breastfeeding for over 3 months.

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The prevalence of hepatitis C virus infection in hemodialysis patients in Japan was examined using sera from 418 patients from six dialysis units in 1989. The authors made use of an enzyme-linked immunosorbent assay (Ortho Diagnostics). Antibody to hepatitis C virus (anti-HCV) was detected in 127 patients (30.4%), the frequency varying from 20.0% to 34.9% in different units. The mean prevalence of anti-HCV was 20 times higher than that in blood donors. Anti-HCV positivity was not associated with antibody to hepatitis B core antigen, which was not a surrogate marker for non-A, non-B hepatitis agents in this study. Another striking finding of this study was that 84.3% of the anti-HCV-positive patients had normal liver function. Anti-HCV positivity correlated positively with the number of blood transfusions and increased with the duration of hemodialysis; however, it was 22.1% even in 113 patients never given blood transfusion. Acquisition of hepatitis C virus by dialysis patients is, therefore, not only through blood transfusions but also because of hepatitis C virus present within the unit itself. Liver dysfunction in the anti-HCV-positive patients was rare.

To investigate the physiologic significance of antibody to human T cell leukemia virus type 1 (HTLV-1) tax gene product (p40tax), 147 male and 243 female HTLV-1 carriers were examined for anti-p40tax, and 104 carriers were checked for anti-p40tax an average of 5.4 times during an 8-year period. Prevalence of anti-p40tax was significantly higher in female (62.6%) than in male subjects (51.0%; P less than .05). Anti-p40tax status did not change in most during the observation period. There were significantly more HTLV-1 carriers among children of anti-p40tax-positive mothers (45.3%) than among those from anti-p40tax-negative mothers (20.0%; P less than .01). However, no significant difference was observed between wives of p40tax-positive and -negative men. The p40tax antibody may be a marker of relative infectivity of HTLV-1, albeit an imperfect one.

The authors investigated families with at least one hepatitis B surface antigen (HBsAg) carried in Okinawa, Japan, to determine possible routes of hepatitis B virus transmission within family units. A total of 175 members of 37 families on the western part of Iriomote Island, Okinawa, were followed up for 2-13 years; 68 were HBsAg-positive at least once. Sera were collected once a year. All serum samples were assayed by radioimmunoassay to determine presence of HBsAg, antibody to HBsAg (anti-HBs), hepatitis B e antigen (HBeAg), antibody to hepatitis B e antigen (anti-HBe) and antibody to hepatitis B core antigen (anti-HBc). In five of the 15 families with a positive mother and negative father, one or more HBsAg-positive children were found. In contrast, an HBsAg-positive child was found in only one of the eight families with a negative mother and positive father. In nine of the 14 families with both parents negative, two or more children were positive. Apparent sibling-to-sibling hepatitis B transmission occurred during the period of observation in four of the families with both parents negative. Eight children less than four years old were HBsAg-positive when first surveyed or became HBsAg carriers when four years of age or younger. No one over four years of age changed from HBsAg-negative to positive. This study found 1) in the family setting, there were cases of apparent maternal transmission but there were more cases of apparent sibling-sibling transmission, and 2) children under four years of age seemed to become carriers more easily than older children.