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The association between the replacement disease and the overall decline in invasive pneumococcal disease among Alaska Native children is investigated. The results have shown that Alaska Native children are experiencing replacement invasive pneumococcal disease with serotypes not covered by heptavalent pneumococcal conjugate vaccine.

The precontact (ie, before contact with Western civilization) Alaska Native diet was primarily limited to protein from fish, moose, caribou, and marine mammals (1). Carbohydrate content increased from 3% to [...]

Background Alaska Native (AN) infants are at risk for severe disease due to respiratory syncytial virus (RSV) and influenza. Maternal immunization protects young infants through transplacental antibody transfer. RSV- and influenza-specific transplacental antibody transfer in mother–infant pairs has not previously been evaluated in the AN population. Methods Serum samples collected during pregnancy and at birth from AN mother–infant pairs in the Yukon-Kuskokwim Delta region (YKD) of Alaska (2000–2011; n = 75) and predominantly white pairs in Seattle, Washington (2014–2016; n = 57), were tested for RSV and influenza antibody using a microneutralization and hemagglutination inhibition assay, respectively, and compared between sites. Results Mean RSV antibody concentrations in pregnant women in YKD and Seattle were similar (log2 RSV antibody 10.6 vs 10.7, P =.86), but cord blood RSV antibody concentrations were significantly lower in infants born to mothers in YKD compared with Seattle (log2 RSV antibody 11.0 vs 12.2, P <.001). Maternal and cord blood influenza antibody concentrations were lower for women and infants in YKD compared with Seattle for all 4 influenza antigens tested (all P <.05). The mean cord to maternal RSV antibody transfer ratio was 1.15 (standard deviation [SD], 0.13) in mother–infant pairs in Seattle compared with 1.04 (SD, 0.08) in YKD. Mean cord blood to maternal antibody transfer ratios for influenza antigens ranged from 1.22 to 1.42 in Seattle and from 1.05 to 1.59 in YKD. Conclusions Though the transplacental antibody transfer ratio was high (>1.0) for both groups, transfer ratios for RSV antibody were significantly lower in AN mother–infant pairs. Further studies are needed to elucidate the impact of lower transplacental antibody transfer on infant disease risk in rural Alaska. Alaska Native and continental US mother-infant pairs have high transplacental antibody transfer ratios (>1.0) for influenza and respiratory syncytial virus, but anti-respiratory syncytial virus antibody levels are significantly lower in Alaska Native pairs than in those from the continental US. [ABSTRACT FROM AUTHOR]

Abstract: Background: Helicobacter pylori is one of the most common human infections in the world, and studies in Alaska Native people, as well as other Indigenous peoples, have shown a high prevalence of this gastric infection. This study was undertaken to determine the prevalence of H. pylori infection by urea breath test (UBT) and anti‐ H. pylori IgG among Alaskans living in four regions of the state and to identify factors associated with infection. Methods: A convenience sample of persons > 6 months old living in five rural and one urban Alaskan community were recruited from 1996 to 1997. Participants were asked about factors possibly associated with infection. Sera were collected and tested for anti‐ H. pylori IgG antibodies; a UBT was administered to participants > 5 years old. Results: We recruited 710 people of whom 571 (80%) were Alaska Native and 467 (66%) were from rural communities. Rural residents were more likely to be Alaska Native compared with urban residents (P < .001). Of the 710 people, 699 (98%) had a serum sample analyzed, and 634 (97%) persons > 5 years old had a UBT performed. H. pylori prevalence was 69% by UBT and 68% by anti‐ H. pylori IgG. Among those with a result for both tests, there was 94% concordance. Factors associated with H. pylori positivity were Alaska Native racial status, age ≥ 20 years, rural region of residence, living in a crowded home, and drinking water that was not piped or delivered. Conclusions: Helicobacter pylori prevalence is high in Alaska, especially in Alaska Native persons and rural residents. Concordance between UBT and serology was also high in this group. Two socioeconomic factors, crowding and drinking water that was not piped or delivered, were found to be associated with H. pylori positivity. [ABSTRACT FROM AUTHOR]

Objective: To measure the trends in traditional marine food intake and serum vitamin D levels in Alaska Native women of childbearing age (20-29 years old) from the 1960s to the present.Design: We measured a biomarker of traditional food intake, the δ15N value, and vitamin D level, as 25-hydroxycholecalciferol (25(OH)D3) concentration, in 100 serum samples from 20-29-year-old women archived in the Alaska Area Specimen Bank, selecting twenty-five per decade from the 1960s to the 1990s. We compared these with measurements of red-blood-cell δ15N values and serum 25(OH)D3 concentrations from 20-29-year-old women from the same region collected during the 2000s and 2010s in a Center for Alaska Native Health Research study.Setting: The Yukon Kuskokwim Delta region of south-west Alaska.Subjects: Alaska Native women (n 319) aged 20-29 years at the time of specimen collection.Results: Intake of traditional marine foods, as measured by serum δ15N values, decreased significantly each decade from the 1960s through the 1990s, then remained constant from the 1990s through the present (F 5,306=77·4, P<0·0001). Serum vitamin D concentrations also decreased from the 1960s to the present (F 4,162=26·1, P<0·0001).Conclusions: Consumption of traditional marine foods by young Alaska Native women dropped significantly between the 1960s and the 1990s and was associated with a significant decline in serum vitamin D concentrations. Studies are needed to evaluate the promotion of traditional marine foods and routine vitamin D supplementation during pregnancy for this population. [ABSTRACT FROM AUTHOR]

Here we describe the relationships between serotypes, genotypes, and antimicrobial susceptibility among isolates causing invasive pneumococcal disease in Alaskan children during the pneumococcal conjugate vaccine (PCV) era. From 2001 to 2013 we received 271 isolates representing 33 serotypes. The most common serotypes were 19A (29.5%, n = 80), 7F (12.5%, n = 34), 15B/C (6.3%, n = 17), and 22F (4.8%, n = 13). Multilocus sequence typing identified 11 clonal complexes (CC) and 45 singletons. Five CCs accounted for 52% (141/271) of the total: CC199 (21% [ n = 57], serotypes 19A, 15B/C), CC191 (12.2% [ n = 33], serotype 7F), CC172 (10.3% [ n = 28], serotypes 19A, 23A, 23B), CC433 (4.4% [ n = 12], serotype 22F), and CC100 (4.4% [ n = 12], serotype 33F). The proportion of isolates nonsusceptible to erythromycin and tetracycline increased after 13-valent PCV use (14% [ n = 30] versus 29% [ n = 14]; P = 0.010) and (4% [ n = 9] versus 22% [ n = 11]; P < 0.001), respectively. The genetic diversity also increased after 13-valent PCV use (Simpson's diversity index =0.95 versus 0.91; P = 0.022). [ABSTRACT FROM AUTHOR]

Background. The 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. Objective. To 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). Design. A 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 0US, 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. Results. The total cost of screening for the cohort by AFP 0US 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 0US and $41,000 per extra YLG. Conclusions. Although US-alone HCC screening might have yielded more YLG than AFP 0US, the reduced costs of the AFP 0US method could expand access to HCC screening in resource constrained settings. [ABSTRACT FROM AUTHOR]

Background. Community-acquired methicillin-resistant Staphylococcus aureus and methicillin-sensitive S. aureus infections 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. aureus infection. Objective. A 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 design. Using 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. Results. We 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. Conclusions. These 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. [ABSTRACT FROM AUTHOR]

Introduction. Recent 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. Methods. We 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. Results. In 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). Fiftythree 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. Conclusions. In 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background & Aims: Persistence of hepatitis B e antigen (HBeAg) in chronic hepatitis B has been associated with increased risk for development of cirrhosis and hepatocellular carcinoma. Five hepatitis B virus genotypes were identified in Alaska Native persons; we analyzed clearance of HBeAg by age and genotype. Methods: In this prospective cohort study, 1158 Alaska Native persons throughout Alaska were tested serially for HBeAg for a median of 20.5 years and were genotyped. Initial and final HBeAg-positive specimens, time to clearance, age at clearance, and subsequent HBeAg results were analyzed for persons initially HBeAg-positive. Subsequent HBeAg results were analyzed for persons initially negative. Results: Genotypes A, B, C, D, and F were identified. Genotype C persons initially HBeAg-positive were more likely than those with other genotypes to be positive on initial and final specimens (P < .001 for each) and time to HBeAg clearance was longer (P < .001). Age at which 50% of persons cleared HBeAg was <20 years for those infected with genotypes A, B, D, and F and 47.8 years in genotype C (P < .001). After losing HBeAg, those with genotypes C and F were more likely to revert to the HBeAg-positive state (P < .001). Conclusions: Genotype may have a strong effect on mode of transmission and outcome. Genotype C may have been responsible for most perinatal transmission, given that seroconversion from HBeAg occurs decades later than in other genotypes. [Copyright &y& Elsevier]

ABSTRACT. Objective. The incidence of hospitalization for respiratory syncytial virus (RSV) infection among Alaska Native children is much higher than among non-Native populations in the United States. We conducted this study to better understand factors associated with hospitalization attributable to RSV infection in this high-risk population. Design. Case-control study, including collection of cord blood for RSV-neutralizing antibody measurement. Setting. Remote region of southwest Alaska served by 1 regional hospital and 2 referral hospitals. Subjects. Case-patients identified through surveillance for RSV infection and matched control subjects without acute respiratory infection hospitalization. Results. Breastfeeding was associated with a lower risk of RSV hospitalization (odds ratio: 0.34), whereas underlying medical conditions (primarily prematurity) were associated with increased risk (odds ratio: 6.25). Environmental factors associated with a higher risk of hospitalization included household crowding (4 or more children in the household and crowding index ≥ 2). The level of maternal RSV-neutralizing antibody was not associated with the risk of hospitalization. Conclusions. In this region with extremely high risk of RSV hospitalization, several measures, such as encouraging breastfeeding and reducing household crowding, could reduce the risk of hospitalization attributable to RSV. Pediatrics 2002;109:210-216; respiratory syncytial virus, Alaska Natives, breastfeeding. [ABSTRACT FROM AUTHOR]