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Background: The duration of protection afforded by hepatitis B vaccination is unknown. Objective: To determine antibody persistence and protection from hepatitis B virus (HBV) infection. Design: Prospective cohort study. Setting: 15 villages in southwest Alaska. Participants: 1578 Alaska Natives vaccinated at age 6 months or older. Intervention: During 1981-1982, participants received 3 doses of plasma-derived hepatitis B vaccine. This cohort was followed annually over the first 11 years, and 841 (53%) persons were tested at 15 years. Measurements: Antibody to hepatitis B surface antigen (anti-HBs), markers of HBV infection, and testing to identify HBV variants. Results: Levels of anti-HBs in the cohort decreased from a geometric mean concentration of 822 mlU/mL after vaccination to 27 mlU/mL at 15 years. Initial anti-HBs level, older age at vaccination, and male sex were associated with persistence of higher anti-HBs levels at 15 years when analyzed by a longitudinal linear mixed model. After adjustment for initial anti-HBs level and sex, those vaccinated at age 6 months to 4 years had the lowest anti-HBs level at 15 years. Asymptomatic breakthrough infections were detected in 16 participants and occurred more frequently in persons who did not respond to vaccination than those who responded (P= 0.01). Among infected persons with viremia, 2 were infected with wild-type HBV and 4 had HBV surface glyco-protein variants, generally accompanied by wild-type HBV. Limitations: The loss of participants to follow-up at 15 years was 47%. However, characteristics of persons tested were similar to those of persons lost to follow-up. Conclusions: Hepatitis B vaccination strongly protected against infection for at least 15 years in all age groups. Antibody levels decreased the most among persons immunized at 4 years of age or younger.

Background: To prevent serious pneumococcal infections, 23-valent pneumococcal polysaccharide vaccine is recommended for individuals over 24 months of age with chronic predisposing diseases and for healthy older adults. This nonrandomized controlled study in rural Alaska assessed the immunogenicity of revaccination in adults. Methods: Twenty-six adults, 33 to 88 years of age, vaccinated a mean of 7.4 years before this study, were matched to 26 previously unvaccinated subjects by age, number of chronic diseases, sex, and ethnicity. One or more chronic diseases were validated in 62% of subjects (32 of 52). All received a first or second intramuscular dose of pneumococcal vaccine. Antibody levels were determined by radioimmunoassay for 12 pneumococcal capsular serotypes immediately before and 20 to 84 days after vaccination. Results: Six to 9 years after primary vaccination, over one third of serotype-specific antibody levels were below 500 ng of antibody nitrogen per milliliter, equal to the percentage in unvaccinated subjects of similar age. Antibody levels against all pneumococcal serotypes rose to similar levels after primary vaccination and revaccination, and 54% and 55%, respectively, of subjects who received primary vaccination and revaccination had at least a 1.4-fold increase in antibody levels. Only the antibody level for serotype 4 remained low. Neither gender nor age affected peak response. For those with chronic diseases, there was a trend toward fewer low antibody levels against three or more serotypes after revaccination (two subjects [13%]) than after primary vaccination (five subjects [31%]). Conclusions: Following the initial immunization of high-risk and elderly patients with pneumococcal polysaccharide, pneumococcal antibody levels appear to wane with time. Primary vaccination and revaccination 6 or more years after a first dose of pneumococcal vaccine stimulate comparable mean antibody levels. (Arch Intern Med. 1994;154:2209-2214)

Eskimos living in rural southwestern Alaska depend on fish and marine mammals as major sources of subsistence food. Fatty acid concentrations in 80 Yupik Eskimos living in either a coastal or river village of southwestern Alaska were compared with those of non-Native control subjects. Concentrations of total plasma [omega]-3 fatty acids, eicosapentaenoic acid (20:5[omega]-3), and docosahexaenoic acid (22:6[omega])-3) were 4.3, 13, and 6.8 times higher, respectively, in Native participants than in non-Native control subjects. Concentrations of these fatty acids were higher in coastal-village than in river-village participants; concentrations paralleled consumption of marine mammal oil and marine fish. The ratios of eicosapentaenoic to arachidonic acid for adult coastal- and river-village participants were 1.16 and 0.70, respectively, 14 and 9 times those of non-Native adults, respectively. There was no increase in the mean bleeding times of Native participants of either village.

Similar RSV antibody levels in Alaska-native (AN) and non-AN womenAN infants’ cord blood RSV antibody levels lowerMaternal and cord blood influenza antibody levels lower in AN women and infantsAN mother–infant pairs’ RSV antibody transfer ratios significantly lower

Hepatitis B is an inflammatory condition affecting the liver that is caused by hepatitis B virus (HBV), which is transmitted mainly by blood and blood products. Protection against this chronic, sometimes fatal disease can often be afforded by immunization with a vaccine specific for HBV. To determine the efficacy and duration of protection that HBV immunization might confer on a large group of Yupik Eskimos (an Eskimo population with a high endemic HBV infection rate), a study was carried out in which 1,581 susceptible persons were immunized with the manufacturer-recommended three-dose regimen. Blood levels of HBV antibodies (molecules produced by the immune system to combat potential HBV infection) were measured annually for seven years. Antibody levels dropped off moderately for the first two years after immunization and were fairly constant for the remaining five years. An arbitrary standard was suggested as a first approximation of adequate HBV antibody levels for the purpose of indicating protection from HBV infection (10 milli-International Units per milliliter of blood); between 52 and 87 percent of the immunized subjects maintained these levels for the seven-year period, depending on age (older subjects showed a more rapid decline than younger). During the seven years following the first dose of vaccine, five responders (subjects who showed an increase in HBV antibody level) and three other persons showed blood changes suggestive of infection with HBV. No subjects developed overt symptoms of HBV, or showed evidence of HBV in the blood when tested by direct measurement. Hence, HBV immunization confers significant protection against infection by HBV. These results suggest that boosting the initial inoculation is not necessary for at least seven years. (Consumer Summary produced by Reliance Medical Information, Inc.)

ABSTRACTHepatitis B antibody persistence was assessed in individuals who had previously received a vaccine booster. We measured hepatitis B surface antigen antibody (anti-HBs) levels 7 to 9 years post-hepatitis B booster in individuals with primary vaccination at birth. While 95 (91.3%) of 104 participants had detectable anti-HBs (minimum, 0.1 mIU/ml; maximum, 1,029 mIU/ml), only 43 (41%) had protective levels of =10 mIU/ml. Pre- and week 4 postbooster anti-HBs levels were significant predictors of hepatitis B immunity at follow-up (P< 0.001). Almost all participants had detectable anti-HBs 7 to 9 years after the hepatitis B vaccine booster, but less than half had levels =10 mIU/ml.

During 1996 to 2000, Alaska Native children aged <5 years from Yukon Kuskokwim Delta (YKD) had invasive pneumococcal disease (IPD) rates 10-fold higher than non-Alaska Native children (547100,000yr versus 56100,000yr). After 7-valent pneumococcal conjugate vaccine (PCV7) introduction, IPD rates decreased to 148 per 100,000 during 2001 to 2004, increasing to 426 per 100,000 during 2005 to 2007 due to non-vaccine serotype disease. In 2009, we evaluated safety, immunogenicity and impact of 13-valent PCV (PCV13) in YKD children.

Objectives.To examine trends in diabetes prevalence, incidence, complications and mortality between 1985 and 2006 among Alaska Native people.Study design.We used data from the population-based Alaska Native Diabetes Registry, which includes all people who receive care in the Alaska Tribal Health System.Methods.We compared the periods of 1986–1990 and 2002–2006 for diabetes-related amputations, renal replacement and mortality using Poisson regression. Complications and mortality data were examined for trends using Poisson regression. Survival analyses for those diagnosed since 31 December 1985 were performed using the Cox proportional hazard model.Results.Age-adjusted diabetes prevalence increased from 17.3 in 1985 to 47.6/1,000 in 2006. The number of Alaska Native people living in Alaska with diabetes increased from 610 in 1985 to 3,386 in 2006. Diabetes incidence rates have also increased. Comparing age-adjusted rates for the 5-year periods 1986–1990 and 2002–2006, amputations decreased from 5.3 to 2.6/1,000, renal replacement decreased from 3.3 to 1.2/1,000 and mortality decreased from 41.7 to 33.2/1,000. Yearly analyses showed a downward trend for amputations, renal replacement and mortality rates. Survival analyses showed a significantly higher hazard ratio for any amputations, major amputations and renal replacement for the earlier time period compared to the most recent time period.Conclusions.An increase in risk factors, awareness, funding and case-finding may be contributing to the increase in prevalence and incidence of diagnosed diabetes. While diabetes prevalence and incidence are increasing among Alaska Native people, our results suggest that even in remote, rural areas, complications and mortality can be reduced.

From 1993 to 1996, Alaska Native infants younger than 1 year of age from the Yukon-Kuskokwim Delta region in Alaska experienced a respiratory syncytial virus (RSV) hospitalization rate 5 times higher than the U.S. general infant population rate. This article describes the trends in hospitalization and prolonged annual season of RSV hospitalizations in Yukon-Kuskokwim children from 1993 to 2004 and discusses factors associated with high rates of RSV hospitalization and the impact of interventions to decrease RSV hospitalizations in this population.

During 1993 to 1996, Alaska Native infants <1 year of age from the Yukon Kuskokwim (YK) Delta in Alaska experienced a respiratory syncytial virus (RSV) hospitalization rate 5 times the U.S. general infant population rate. We describe trends in lower respiratory tract infection (LRTI) and RSV hospitalizations in YK children from 1994 to 2004.

The relationship between atopic disease and serum IgE levels varies among populations and geographic regions. The close association of atopy with IgE may not occur in subarctic populations as it does in developed countries in temperate climates.

Background: Despite routine vaccination and declining disease rates, Haemophilusinfluenzae type b (Hib) invasive disease still occurs in rural Alaska. Colonization studiesindicate persistent transmission of Hib among village residents, including adults. As partof a project to eliminate Hib carriage in 3 rural villages, we evaluated a cohort of Alaskaadults for antibody response and reactogenicity to a single dose of Hib conjugate vaccine(HbOC).Methods: 75 previously unvaccinated, randomly-selected adults in one village received asingle dose of HbOC vaccine and completed a side-effects diary. Sera and oropharyngealspecimens were collected at baseline, 2 months and 1 year.Results: No participants were colonized with Hib or reported serious side-effects. Atbaseline, 97% of adults had IgG anti-PRP concentrations > 0.15 µg/mL, 69% >1 µg/mL,and 28% > 5 µg/mL. Two months post-vaccination, 100% of participants hadconcentrations > 0.15 µg/mL, 93% >1 µg/mL, and 86% >5 µg/mL. After 1 year, 98% hadIgG anti-PRP concentrations > 0.15 µg/mL, 86% > 1 µg/mL, and 67% >5 µg/mL. GMCswere 1.9, 33.3 and 8.4 µg/mL at baseline, 2 months and 1 year post-vaccine, respectively(p

Alaska Native (AN) children were at high risk of acquiring hepatitis B virus (HBV) infection before vaccination began in 1983. We evaluated the long-term protection from hepatitis B (HB) vaccination among AN children immunized when infants.

AbstractObjective.To compare characteristics of persons in rural northern communities who participated in a study on antimicrobial use and drug-resistant Streptococcus pneumoniae(SP) to those who did not participate.Study Design.The original study (1998–2000) was a community-based, controlled intervention trial designed to determine the penicillin susceptibility of nasopharyngeal SP isolates in relation to community-wide use of antibiotics. The study continued after 2000, in a subset of the original communities, to prospectively evaluate the impact of the heptavalent pneumococcal conjugate vaccine on the carriage of SP. The results presented here are an analysis of the first five years of data.Methods.We conducted annual surveys (1998–2002) for nasopharyngeal colonization of SP using a volunteer sample of residents in rural communities. Medical chart reviews for health clinic visitation and antibiotic use were completed for all village residents.Results.Participants were younger (22.8 vs. 28.4 years), had more health clinic utilization (3.3 vs. 2.4 visits) and received more antibiotics (1.0 vs. 0.6 courses) than non-participants. Differences between participants and non-participants were similar across all years of the study.Conclusions.Our study provides further empirical evidence that selection bias should be considered when designing studies. However, a volunteer sample provided internal consistency for comparison of our main study outcomes across time. (Int J Circumpolar Health 2005; 64(1):16–25)

The duration of protection after hepatitis B vaccination of infants is unknown.

To characterize the epidemiology of Alaska Native children hospitalized for respiratory syncytial virus infections, we reviewed records of hospitalizations during the winter seasons of 1991 to 1992 and 1992 to 1993 at a hospital in Anchorage and a rural hospital in the Yukon Kuskokwim Delta (YKD) region of southwestern Alaska. The median age of hospitalization for respiratory syncytial virus infection was 2 months of age for YKD residents and 4.5 months for Anchorage residents. Sixteen percent of the hospitalized YKD children were less than 1 month of age, whereas the same was true for only 3 of the Anchorage children. Eight percent of the YKD patients required mechanical ventilation, whereas none of the Anchorage patients required ventilation. The median hospital stay was 4.8 days for YKD patients and 3.2 days for Anchorage patients. Hospitalization rates for infants less than 1 year of age were 33/1000 for Alaska Natives in Anchorage and 100/1000 for those in the YKD region. The extremely high hospitaliza

Haemophilus influenzaetype b (Hib) is a major cause of serious childhood bacterial infections. Before 1989 Alaska Native infants in the Yukon Kuskokwim Delta (YKD) had the highest recorded Hib disease rate, 2960: 100 000 in children less than 1 year of age with 6 to 35 (mean, 13) cases/year between 1980 and 1988. In July, 1989, Alaska Area Nativa Health Service initiated a passive immunization project in the YKD using bacterial polysaccharide immunoglobulin (BPIG) administered at 3-month intervals to prevent Hib infections in infants less than 13 months of age. On January 1, 1991, after licensure of Hib conjugate vaccines for infants, the program was modified to a passive-active strategy using BPIG at birth and Pedvax HIB at 2, 4 and 12 months of age. Between July 1, 1989, and December 31, 1990, 80 of YKD children less than 1 year of age received at least 1 dose of BPIG. During this period there were 7 Hib cases in this age group, but only 1 of the cases had received any BPIG. Between January 1, 1991, and December 31, 1992, 4 Hib cases occurred in 2 YKD children. During the combined period, July 1, 1989, to December 31, 1992, the incidence of Hib disease for infants less than 1 year of age was 302:100 000. A dramatic decrease in Hib disease was observed in this high incidence region concurrent with implementation of passive and passive-active immunization strategies.

• OBJECTIVES. —To (1) determine the frequency and severity of sequelae of Haemophilus influenzae type b and Streptococcus pneumoniae meningitis in Alaska Native children, (2) compare morbidity and mortality of H influenzae b and S pneumoniae meningitis, and (3) evaluate the applicability of the Herson-Todd prognostic score (HTPS) to both H influenzae b and S pneumoniae meningitis in this population. DESIGN. —A retrospective study of all cases of H influenzae b and S pneumoniae meningitis in Alaska Native children younger than age 5 years. Data on meningitis sequelae, obtained from medical charts and records of the Infant Learning Program, were collected, and incidence of sequelae tabulated. Data obtained on admission to the hospital were used to calculate HTPS. SETTING. —Indian Health Service facility for the Yukon-Kuskokwin Delta region of southwest Alaska. STUDY SUBJECTS. —51 of 63 Alaska Native children with H influenzae b meningitis and 13 of the same 63 Alaska Native children with S pneumoniae meningitis occurring between 1980 and 1988. One child was infected with both organisms, producing a total of 64 cases for study. SELECTION PROCEDURES. —Cases were identified by surveillance for these diseases between January 1,1980, and December 31, 1988, maintained by the Arctic Investigations Program, Centers for Disease Control. MEASUREMENTS AND RESULTS. —Sequelae of bacterial meningitis caused by H influenzae b were equal to or exceeded rates of sequelae described in other children in the United States. After H influenzae b meningitis, motor abnormalities (29%) and hydrocephalus (7%) occurred two to four times more often in Alaska Native children than in children in other parts of the United States. Differences in severity of H influenzae b sequelae could not be accounted for by microbiologic markers of the H influenzae b strain, including ampicillin sensitivity, biotype, outer membrane protein type, or electropherotype. Numbers of cases of S pneumoniae meningitis were too small for statistically valid comparison, but sequelae of S pneumoniae meningitis occurred in roughly equal proportion as sequelae of H influenzae b meningitis. The HTPS was applied to Alaska Native children with H influenzae b meningitis and was found to be very accurate in predicting children with major sequelae. Analysis of the prognostic factors used in deriving the HTPS revealed a unique set of predictors for sequelae in Alaska Native children: seizures at admission, glucose levels in cerebrospinal fluid of less than 1.1 mmol/L; and male gender, with a significant predictive interaction between male gender and age less than 6 months at admission. CONCLUSIONS. —Alaska Native children suffer greater neurologic morbidity as a result of H influenzae b meningitis than do their non-Native counterparts. The HTPS was a good predictor of major sequelae in Alaska Native children with H influenzae b or S pneumoniae meningitis and could be useful in determining which patients need referral to a tertiary care center.(AJDC. 1992;146:560-566)

We analyzed hospitalizations for empyema among Alaska Native (AN) children and the general population of US children <10 years of age during the years 1998 to 2007. We also analyzed invasive pneumococcal disease in AN children. Between 1998 and 2000, the average annual hospitalization rate for empyema was higher for AN children (51.8 per 100,000/yr) than that for US children (24.2 95% confidence interval: 20.4, 27.9 per 100,000/yr), and had increased in 2004–2007 in both populations (59.6 and 36.0 95% confidence interval: 30.1, 41.8, respectively). Pneumococcal empyema increased in AN children despite a decrease in invasive pneumococcal disease pneumonia.

BackgroundCommunity-acquired methicillin-resistant Staphylococcus aureusand methicillin-sensitive S. aureusinfections are common to south-western Alaska and have been associated with traditional steambaths. More than a decade ago, recommendations were made to affected communities that included preventive skin care, cleaning methods for steambath surfaces, and the use of protective barriers while in steambaths to reduce the risk of S. aureusinfection.ObjectiveA review of community medical data suggested that the number of skin infection clinical encounters has increased steadily over the last 3 years and we designed a public health investigation to seek root causes.Study designUsing a mixed methods approach with in-person surveys, a convenience sample (n=492) from 3 rural communities assessed the range of knowledge, attitudes and practices concerning skin infections, skin infection education messaging, prevention activities and home self-care of skin infections.ResultsWe described barriers to implementing previous recommendations and evaluated the acceptability of potential interventions. Prior public health messages appear to have been effective in reaching community members and appear to have been understood and accepted. We found no major misconceptions regarding what a boil was or how someone got one. Overall, respondents seemed concerned about boils as a health problem and reported that they were motivated to prevent boils. We identified current practices used to avoid skin infections, such as the disinfection of steambaths. We also identified barriers to engaging in protective behaviours, such as lack of access to laundry facilities.ConclusionsThese findings can be used to help guide public health strategic planning and identify appropriate evidence-based interventions tailored to the specific needs of the region.

BackgroundThe American Association for the Study of Liver Diseases (AASLD) recommends semi-annual hepatocellular carcinoma (HCC) screening using ultrasound (US) in persons with chronic hepatitis B (CHB) virus infection at high risk for HCC such as Asian males aged ≥40 years and Asian females aged ≥50 years.ObjectiveTo analyse the cost-effectiveness of 2 HCC screening methods in the Alaska Native (AN) health system: US-alone, or screening by alpha-fetoprotein (AFP) initially and switching to US for subsequent screenings if AFP >10 ng/mL (AFP→US).DesignA spreadsheet-based model was developed for accounting the costs of 2 hypothetical HCC screening methods. We used epidemiologic data from a cohort of 839 AN persons with CHB who were offered HCC screening by AFP/US semi-annually during 1983–2012. We assumed that compared with AFP→US, US-alone identifies 33% more tumours at an early stage (defined as a single tumour ≤5 cm or ≤3 tumours ≤3 cm in diameter). Years of life gained (YLG) attributed to screening was estimated by comparing additional years of survival among persons with early- compared with late-stage tumours. Screening costs were calculated using Medicare reimbursement rates in 2012. Future screening costs and YLG were projected over a 30-year time horizon using a 3% discount rate.ResultsThe total cost of screening for the cohort by AFP→US would have been approximately $357,000 ($36,000/early-stage tumour detected) compared to $814,000 ($59,000/early-stage tumour detected) by US-alone. The AFP→US method would have yielded an additional 27.8 YLG ($13,000/YLG) compared with 38.9 YLG ($21,000/YLG) for US-alone. Screening by US-alone would incur an additional $114,000 per extra early-tumour detected compared with AFP→US and $41,000 per extra YLG.ConclusionsAlthough US-alone HCC screening might have yielded more YLG than AFP→US, the reduced costs of the AFP→US method could expand access to HCC screening in resource constrained settings.

IntroductionRecent epidemiologic research studies in rural Alaska have examined risk factors for infectious diseases collected at the household level. Examples include the health effects of in-home piped water and household air quality. Because the exposure is measured at the household level, it is necessary to determine if participants remained in the same house throughout the course of follow-up.MethodsWe used data from a pneumococcal nasopharyngeal carriage study in 8 rural Alaska villages [3 regions; average number of persons: 642 (min 210, max 720 per village) to quantify changes in household membership and individual movements from 2008 to 2010. We define a household as a group of individuals living in a home together. Because the same households participated in carriage surveys over several years, we could determine changes on an annual basis. We calculated the percentage of households with a ≥1 person change in household members from year to year. Additionally, we present the percentage of individuals that changed households during consecutive years.ResultsIn 3 regions of Alaska, the average household size was 5 persons. Between 2008 and 2009, 50% (250/497) of households had a change in their membership (≥1 person in-migrated or out-migrated). Fifty-three percent of households experienced some migration of their members between 2009 and 2010. A total of 27 and 15% of households had a change of ≥2 and ≥3 persons, respectively. The percentage of households with movement was similar among the 3 rural regions and varied from 42 to 63% between villages. At the individual level, an average of 11% of persons changed households between years. The group with the most movement between houses was persons 18–29 years of age (19%), and least movement was in 5–10 and 50–64 years of age (6%). There was no difference in movement by gender.ConclusionsIn rural Alaska, 52% of households experienced movement of members between years and 11% of individuals change households. These are important demographic figures to consider when planning and designing studies that measure an epidemiological exposure at the household level. Power and sample size calculations should account for the loss to follow-up associated with in- and out-migration of individuals from households.

From January 1986 through December 1990,672 cases of invasive pneumococcal disease were identified. From these, 574 pneumococcal isolates were recovered from normally sterile sites (blood, cerebrospinal and pleural fluid); 92% were serotypes represented in the 23-valent pneumococcal polysaccharide vaccine. The most common serotypes from children <2 years old were 4, 6B, 9V, 14, 18C, 19F, and 23F, recovered from 83% ofAlaska Native and 75.1%ofnonnative children with invasive disease. Moderate penicillin resistance (MIC, 0.1-1.0 “”g/mL) was found in 3.8% of isolates. All were sensitive to chloramphenicol, vancomycin, rifampin, ceftriaxone, cefotaxime, cephalothin, and cefaclor. However, in the Yukon-Kuskokwim Delta region, 16.9% of isolates were moderately resistant to penicillin, and 10.8% were resistant to erythromycin and 6.2% to trimethoprim-sulfamethoxazole; the number resistant to two or more antibiotics increased significantly during surveillance. All multiply resistant isolates were serotype 6B, and all were from Alaska Native patients < 2 years old.

To assess prevention strategies for pneumococcal disease in Alaska, prospective surveillance during 1986-1990identified672invasivepneumococcalinfections,including315amongAlaska Natives. Age-adjusted annual incidence was 74 per 100,000 for Alaska Natives and 16 per 100,000 for nonnatives. The annual incidence in Alaska Native children <2 years old was 624 per 100,000; rates of 84 per 100,000 for meningitis and 290 per 100,000 for bacteremic pneumonia were 8-10 times higher than for other US groups. By age 75, cumulative incidence (7%) and mortality (1%) in Alaska Natives were almost 4 times higher than for nonnatives. Only 17% of Alaska Native adults with predisposing conditions and invasive infections previously received pneumococcal vaccine. For Alaska Natives, a proposed heptavalent conjugate pneumococcal vaccinewillincludeserotypesresponsiblefor85%ofinvasiveisolatesfromchildren <2 yearsbut only 32% of those from adults. The 23-valent polysaccharide pneumococcal vaccine, which contains >94% of serotypes identified in Alaska Native toddlers and adults, should be used more widely.

Background Alaska Native women experience higher invasive cervical cancer incidence and mortality rates than US whites despite a long-standing cancer screening programme including recommendations for annual Pap smears. Methods To determine the frequency and results of cytological screening preceding their diagnoses, a histological and medical record review was completed for 44 of 46 Alaska Native cases of invasive cervical cancer from a defined population. An interval cancer (no prior dysplasia and a negative screening report within 3 years of diagnosis) was determined for 23 women. Mean number of negative reports during the 3- and 5-year intervals before diagnosis was 1.7 and 2.6 respectively. The age-adjusted incidence rate for all cervical cancer was 24.0/100 000 women/year and for interval cancer with single and multiple negative reports during the 3-year interval before diagnosis it was 11.6, and 9.6 respectively. Senssitivity of a Pap smear to demonstrate dysplasia during the year before diagnosis was 51%. Conclusions Annual cytological screening of all Alaska Native women with current methods would provide earlier diagnoses for only an additional 15% of cervical cancer cases. Plausible but unproven explanations indude rapid progression through precursor stages of neoplasia or random screening errors. Improved or ancillary screening methods appear necessary.

Cardiac disease mortality in Alaska, from both ischaemic and rheumatic heart disease, is of interest given the high consumption of fish and high streptococcal disease rates in the indigenous population. Uniformly coded underlying cause-of-death data for the period 1979–1988, compared with that from 1955–1965, indicated that deaths from all cardiac diseases combined, have been increasing in Alaska Natives over the past 30 years. Recent mortality from all cardiac, ischaemic, and rheumatic heart diseases in Alaska Natives were 80%, 61%, and 202% of those corresponding levels in Alaskan whites, whose cardiac mortality closely profiles US whites. Alaska Native men aged 30–45 years had higher overall mortality rates for cardiac diseases than did whites because of higher mortality rates of rheumatic heart disease and cardiomyopathy. Elderly Alaska Native men had lower rates than whites, reflecting less ischaemic heart disease mortality. The lowest levels of ischaemic heart disease mortality, less than one-third that of US whites, occurred in Alaskan Eskimos who lived in an area with documented patterns of high salmon consumption by individuals with high blood concentrations of omega-3 fatty acids. Elevated mortality from non-ischaemic heart disease and previously documented genetic markers suggest associations deserving further study.

Hepatitis B vaccine is effective in preventing infection with hepatitis B virus (HBV), but its duration of protection is unknown. To examine the effect of exposure to HBV on an immunized population, data were analyzed from a cohort of Alaska Natives who were immunized and then followed up annually for 10 years. A boost in antibody to hepatitis B surface antigen (anti-HBs) was defined as a fourfold rise in levels to 20 mIU/mL that was not accompanied by the presence of antibody to hepatitis B core antigen or attributable to interim vaccination. During 10 years of follow-up, 8.2% of 1,595 vaccinees had boosts in anti-HBs. Persons with boosts did not differ significantly from those without boosts in terms of age, gender, village, initial level of anti-HBs, or level of anti-HBs before the boost. These results underscore the continued exposure to HBV among vaccinees and the continued protection against disease that the vaccine provides.

To assess the epidemiologic characteristics of the population susceptible to hepatitis A virus (HAV) infection and determine the natural history of infection, a retrospective survey was done using banked serum specimens. A random sample of 4030 Alaska Natives statewide was selected, stratified by year of birth and community of residence. Overall, 1988 serum samples (49.3%) tested positive for antibody to HAV (anti-HAV). Past HAV infection was strongly age-related, increasing from 7% in persons born since 1975 to 85% among persons born before 1945. Prevalence of infection also varied between regions. In small communities, a clear demarcation typically existed between previously infected older persons and younger anti-HAV-negative persons. This indicated that village-wide outbreaks ofHAV infection have been the norm and appear to be dependent on the presence of a young susceptible population. Widespread vaccination with hepatitis A vaccine to maintain a high proportion of young anti-HAV-positive persons may be successful in preventing future epidemics.

Alaska Native women historically have high rates of sexually transmitted diseases (STDs) and invasive cervical cancer. Their prevalence of cervical infections with human papillomavirus (HPV) in relation to cervical dysplasia was determined with a commercial dot hybridization test for seven HPV genotypes. Type-specific HPV DNA, similarly distributed between genotype groups 16/18 and 31/33/35, was detected in 234 cervical specimens (21%) from 1126 Alaska Native women seeking routine care and colposcopy or from population-based lists. The prevalence of HPV DNA declined with age and increased with sexual activity and cigarette smoking. It was unrelated to use of oral contraceptives or condoms or to STDs. Relative risks associating HPV with increasing severe grades of cervical dysplasia increased markedly with HPV infection, up to 7.1 for high-risk genotypes 16/18 and 14.4 forcoinfection with 31/33/35. These genotypes were detected in 8% of women without dysplasia seeking routine care. Screening for strain-specific HPV DNA may identify women at highest risk for cervical neoplasia.

A hepatitis B virus vaccine demonstration project was conducted in southwest Alaska in 1981–1982 to determine the immunogenicity and efficacy of the vaccine. A total of 1630 susceptible persons in the Alaskan Native population were vaccinated with the recommended three-dose regimen of plasma-derived hepatitis B vaccine, and 94%demonstrated antibody to hepatitis B surface antigen (anti-HBs) at levels 10 mIU/mL. After 10 years of follow-up, 76% of those immunized had anti-HBs levels 10 mIU. During the 10 years following the first dose of vaccine, 13 study participants developed antibody to hepatitis B core antigen (10 vaccine responders, 3 nonresponders), and none developed sustained HBs positivity or had clinical hepatitis. These data suggest that immunization with hepatitis B vaccine continues to provide high levels of protection from clinical disease for at least 10 years.