A survey of knowledge, attitudes, and practices towards skin and soft tissue infections in rural Alaska

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.

Antibody Levels and Protection After Hepatitis B Vaccine: Results of a 30-Year Follow-up Study and Response to a Booster Dose

BACKGROUND

The duration of protection in children and adults resulting from hepatitis B vaccination is unknown. In 1981, we immunized a cohort of 1578 Alaska Native adults and children from 15 Alaska communities aged ≥6 months using 3 doses of plasma-derived hepatitis B vaccine.

METHODS

Persons were tested for antibody to hepatitis B surface antigen (anti-HBs) levels 30 years after receiving the primary series. Those with levels <10 mIU/mL received 1 booster dose of recombinant hepatitis B vaccine 2-4 weeks later and were then evaluated on the basis of anti-HBs measurements 30 days after the booster.

RESULTS

Among 243 persons (56%) who responded to the original primary series but received no subsequent doses during the 30-year period, 125 (51%) had an anti-HBs level ≥10 mIU/mL. Among participants with anti-HBs levels <10 mIU/mL who were available for follow-up, 75 of 85 (88%) responded to a booster dose with an anti-HBs level ≥10 mIU/mL at 30 days. Initial anti-HBs level after the primary series was correlated with higher anti-HBs levels at 30 years.

CONCLUSIONS

Based on anti-HBs level ≥10 mIU/mL at 30 years and an 88% booster dose response, we estimate that ≥90% of participants had evidence of protection 30 years later. Booster doses are not needed.

Antibody Levels and Protection After Hepatitis B Vaccine: Results of a 30-Year Follow-up Study and Response to a Booster Dose

BACKGROUND

The duration of protection in children and adults resulting from hepatitis B vaccination is unknown. In 1981, we immunized a cohort of 1578 Alaska Native adults and children from 15 Alaska communities aged ≥6 months using 3 doses of plasma-derived hepatitis B vaccine.

METHODS

Persons were tested for antibody to hepatitis B surface antigen (anti-HBs) levels 30 years after receiving the primary series. Those with levels <10 mIU/mL received 1 booster dose of recombinant hepatitis B vaccine 2-4 weeks later and were then evaluated on the basis of anti-HBs measurements 30 days after the booster.

RESULTS

Among 243 persons (56%) who responded to the original primary series but received no subsequent doses during the 30-year period, 125 (51%) had an anti-HBs level ≥10 mIU/mL. Among participants with anti-HBs levels <10 mIU/mL who were available for follow-up, 75 of 85 (88%) responded to a booster dose with an anti-HBs level ≥10 mIU/mL at 30 days. Initial anti-HBs level after the primary series was correlated with higher anti-HBs levels at 30 years.

CONCLUSIONS

Based on anti-HBs level ≥10 mIU/mL at 30 years and an 88% booster dose response, we estimate that ≥90% of participants had evidence of protection 30 years later. Booster doses are not needed.

Impact of the 13-valent pneumococcal conjugate vaccine (pcv13) on invasive pneumococcal disease and carriage in Alaska

BACKGROUND

Alaska Native (AN) children have experienced high rates of invasive pneumococcal disease (IPD). In March 2010, PCV13 was introduced statewide in Alaska. We evaluated the impact of PCV13 on IPD in children and adults, 45 months after introduction.

METHODS

Pneumococcal sterile site isolates, reported through state-wide surveillance, were serotyped using standard methods. We defined a pre-PCV13 time period 2005-2008 and post-PCV13 time period April 2010-December 2013; excluding Jan 2009-March 2010 because PCV13 was introduced pre-licensure in one high-risk region in 2009.

RESULTS

Among Alaska children <5 years, PCV13 serotypes comprised 65% of IPD in the pre-PCV13 period and 26% in the PCV13 period. Among all Alaska children <5 years, IPD rates decreased from 60.9 (pre) to 25.4 (post) per 100,000/year (P<0.001); PCV13 serotype IPD decreased from 37.7 to 6.4 (P<0.001). Among AN children <5 years, IPD rates decreased from 149.2 to 60.8 (P<0.001); PCV13 serotype IPD decreased from 87.0 to 17.4 (P<0.001); non-PCV13 serotype IPD did not change significantly. Among persons 5-17 and ≥45 years, the post-vaccine IPD rate was similar to the baseline period, but declined in persons 18-44 years (39%, P<0.001); this decline was similar in AN and non-AN persons (38%, P=0.016, 43%, P=0.014, respectively).

CONCLUSIONS

Forty-five months after PCV13 introduction, overall IPD and PCV13-serotype IPD rates had decreased 58% and 83%, respectively, in Alaska children <5 years of age when compared with 2005-2008. We observed evidence of indirect effect among adults with a 39% reduction in IPD among persons 18-44 years.

Epidemiology of bacterial meningitis in the North American Arctic, 2000-2010

OBJECTIVE

To determine the incidence of meningitis caused by Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae in the North American Arctic during 2000-2010.

METHODS

Surveillance data were obtained from the International Circumpolar Surveillance network. We defined a case of bacterial meningitis caused by H. influenzae, N. meningitidis, or S. pneumoniae as a culture-positive isolate obtained from a normally sterile site in a resident with a meningitis diagnosis.

RESULTS

The annual incidence/100,000 persons for meningitis caused by H. influenzae, N. meningitidis, and S. pneumoniae among all North American Arctic residents was: 0.6, 0.5, and 1.5, respectively; the meningitis incidence among indigenous persons in Alaska and Canada (indigenous status not recorded in Greenland) for those three bacteria was: 2.1, 0.8, and 2.4, respectively. The percentage of pneumococcal isolates belonging to a 7-valent pneumococcal conjugate vaccine serotype declined from 2000-2004 to 2005-2010 (31%-2%, p-value <0.01). During 2005-2010, serotype a caused 55% of H. influenzae meningitis and serogroup B caused 86% of meningococcal meningitis.

CONCLUSIONS

Compared with all North American Arctic residents, indigenous people suffer disproportionately from bacterial meningitis. Arctic residents could benefit from the development of an H. influenzae serotype a vaccine and implementation of a meningococcal serogroup B vaccine.

PCV7-induced changes in pneumococcal carriage and invasive disease burden in Alaskan children

BACKGROUND

Changes in pneumococcal serotype-specific carriage and invasive pneumococcal disease (IPD) after the introduction of pneumococcal conjugate vaccine (PCV7) could inform serotype epidemiology patterns following the introduction of newer conjugate vaccines.

METHODS

We used data from statewide IPD surveillance and annual pneumococcal carriage studies in four regions of Alaska to calculate serotype-specific invasiveness ratios (IR; odds ratio of a carried serotype's likelihood to cause invasive disease compared to other serotypes) in children <5 years of age. We describe changes in carriage, disease burden, and invasiveness between two time periods, the pre-PCV7 period (1996-2000) and the late post-PCV7 period (2006-2009).

RESULTS

Incidence of IPD decreased from the pre- to post-vaccine period (95.7 vs. 57.2 cases per 100,000 children, P<0.001), with a 99% reduction in PCV7 disease. Carriage prevalence did not change between the two periods (49% vs. 50%), although PCV7 serotype carriage declined by 97%, and non-vaccine serotypes increased in prevalence. Alaska pre-vaccine IRs corresponded to pooled results from eight pre-vaccine comparator studies (Spearman's rho=0.44, P=0.002) and to the Alaska post-vaccine period (Spearman's rho=0.28, P=0.029). Relatively invasive serotypes (IR>1) caused 66% of IPD in both periods, although fewer serotypes with IR>1 remained in the post-vaccine (n=9) than the pre-vaccine period (n=13).

CONCLUSIONS

After PCV7 introduction, serotype IRs changed little, and four of the most invasive serotypes were nearly eliminated. If PCV13 use leads to a reduction of carriage and IPD for the 13 vaccine serotypes, the overall IPD rate should further decline.

NOTE

The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Hepatitis B virus antibody levels 7 to 9 years after booster vaccination in Alaska native persons

Hepatitis 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.

Risk Factors for Pneumococcal Colonization of the Nasopharynx in Alaska Native Adults and Children

BACKGROUND

Alaska Native children have high invasive pneumococcal disease (IPD) rates, and lack of in-home running water has been shown to have a significant association with infection. Pneumococcal conjugate vaccines reduced IPD; however, this population saw substantial replacement disease and colonization with nonvaccine serotypes. We evaluated risk factors for nasopharyngeal pneumococcal colonization in Alaska Native adults and children.

METHODS

We conducted annual surveys from 2008 through 2011 of residents of all ages in 8 rural Alaskan villages. Interviews were conducted, medical charts were reviewed, and nasopharyngeal swabs were cultured for Streptococcus pneumoniae. Multivariate logistic regression models were developed for 3 age groups (under 10 years, 10-17 years, and 18 years and older) to determine risk factors for colonization.

RESULTS

We obtained 12 535 nasopharyngeal swabs from 4980 participants. Our population lived in severely crowded conditions, and 48% of households lacked in-home running water. In children <10 years, colonization was associated with lack of in-home running water, household crowding, and more children in the home. Pneumococcal vaccination status was not associated with colonization. In older children and adults, increased number of persons in the household was associated with pneumococcal colonization.

CONCLUSIONS

Higher colonization prevalence may partially explain increased IPD rates seen in those lacking in-home water services. Improving availability of sanitation services and reducing household crowding may reduce the burden of IPD in this population.

Comparison of fecal occult blood tests for colorectal cancer screening in an Alaska Native population with high prevalence of Helicobacter pylori infection, 2008-2012

Introduction

Alaska Native colorectal cancer (CRC) incidence and mortality rates are the highest of any ethnic/racial group in the United States. CRC screening using guaiac-based fecal occult blood tests (gFOBT) are not recommended for Alaska Native people because of false-positive results associated with a high prevalence of Helicobacter pylori-associated hemorrhagic gastritis. This study evaluated whether the newer immunochemical FOBT (iFOBT) resulted in a lower false-positive rate and higher specificity for detecting advanced colorectal neoplasia than gFOBT in a population with elevated prevalence of H. pylori infection.

Methods

We used a population-based sample of 304 asymptomatic Alaska Native adults aged 40 years or older undergoing screening or surveillance colonoscopy (April 2008–January 2012).

Results

Specificity differed significantly (P < .001) between gFOBT (76%; 95% CI, 71%–81%) and iFOBT (92%; 95% CI, 89%–96%). Among H. pylori-positive participants (54%), specificity of iFOBT was even higher (93% vs 69%). Overall, sensitivity did not differ significantly (P = .73) between gFOBT (29%) and iFOBT (36%). Positive predictive value was 11% for gFOBT and 32% for iFOBT.

Conclusion

The iFOBT had a significantly higher specificity than gFOBT, especially in participants with current H. pylori infection. The iFOBT represents a potential strategy for expanding CRC screening among Alaska Native and other populations with elevated prevalence of H. pylori, especially where access to screening endoscopy is limited.

The problem of Helicobacter pylori resistance to antibiotics: a systematic review in Latin America

OBJECTIVES

Latin America has a high prevalence of Helicobacter pylori infection and associated diseases, including gastric cancer. Antibiotic therapy can eradicate the bacterial infection and decrease associated morbidity and mortality. To tailor recommendations for optimal treatments, we summarized published literature and calculated region- and country-specific prevalences of antibiotic resistance.

METHODS

Searches of PubMed and regional databases for observational studies evaluating H. pylori antibiotic resistance yielded a total of 59 independent studies (56 in adults, 2 in children, and 1 in both groups) published up to October 2013 regarding H. pylori isolates collected between 1988 and 2011. Study-specific prevalences of primary resistance to commonly prescribed antibiotics were summarized using random-effects models. Between-study heterogeneity was assessed by meta-regression. As a sensitivity analysis, we extended our research to studies of patients with prior H. pylori-eradication therapy.

RESULTS

Summary prevalences of antimicrobial primary resistance among adults varied by antibiotic, including 12% for clarithromycin (n=35 studies), 53% for metronidazole (n=34), 4% for amoxicillin (n=28), 6% for tetracycline (n=20), 3% for furazolidone (n=6), 15% for fluoroquinolones (n=5), and 8% for dual clarithromycin and metronidazole (n=10). Resistance prevalence varied significantly by country, but not by year of sample collection. Analyses including studies of patients with prior therapy yielded similar estimates. Pediatric reports were too few to be summarized by meta-analysis.

CONCLUSIONS

Resistance to first-line anti-H. pylori antibiotics is high in Latin American populations. In some countries, the empirical use of clarithromycin without susceptibility testing may not be appropriate. These findings stress the need for appropriate surveillance programs, improved antimicrobial regulations, and increased public awareness.

Influenza hospitalizations among american indian/alaska native people and in the United States general population

BACKGROUND

Historically, American Indian/Alaska Native (AI/AN) people have experienced a disproportionate burden of infectious disease morbidity compared with the general US population. We evaluated whether a disparity in influenza hospitalizations exists between AI/AN people and the general US population.

METHODS

We used Indian Health Service hospital discharge data (2001-2011) for AI/AN people and 13 State Inpatient Databases (2001-2008) to provide a comparison to the US population. Hospitalization rates were calculated by respiratory year (July-June). Influenza-specific hospitalizations were defined as discharges with any influenza diagnoses. Influenza-associated hospitalizations were calculated using negative binomial regression models that incorporated hospitalization and influenza laboratory surveillance data.

RESULTS

The mean influenza-specific hospitalization rate/100 000 persons/year during the 2001-2002 to 2007-2008 respiratory years was 18.6 for AI/AN people and 15.6 for the comparison US population. The age-adjusted influenza-associated hospitalization rate for AI/AN people (98.2; 95% confidence interval [CI], 51.6-317.8) was similar to the comparison US population (58.2; CI, 34.7-172.2). By age, influenza-associated hospitalization rates were significantly higher among AI/AN infants (<1 year) (1070.7; CI, 640.7-2969.5) than the comparison US infant population (210.2; CI, 153.5-478.5).

CONCLUSIONS

American Indian/Alaska Native people had higher influenza-specific hospitalization rates than the comparison US population; a significant influenza-associated hospitalization rate disparity was detected only among AI/AN infants because of the wide CIs inherent to the model. Taken together, the influenza-specific and influenza-associated hospitalization rates suggest that AI/AN people might suffer disproportionately from influenza illness compared with the general US population.

Streptococcus pneumoniae non-susceptibility and outpatient antimicrobial prescribing rates at the Alaska Native Medical Center

Background

American Indian/Alaska Native (AI/AN) people suffer substantially higher rates of invasive pneumococcal disease (IPD) than the general US population. We evaluated antimicrobial prescribing data and their association with non-susceptibility in Streptococcus pneumoniae causing IPD in AI/AN people between 1992 and 2009.

Methods

Antimicrobial use data were gathered from the electronic patient management system and included all prescriptions dispensed to Alaska Native patients aged 5 years and older from outpatient pharmacies at the Alaska Native Medical Center (ANMC). Antimicrobial susceptibility data were gathered from pneumococcal isolates causing IPD among Anchorage Service Unit AI/AN residents aged 5 years and older. Data were restricted to serotypes not contained in the pneumococcal vaccine (PCV7).

Results

Over the study period, overall antimicrobial prescribing increased 59% (285/1,000 persons/year in 1992 to 454/1,000 persons per year in 2009, p<0.001). Trimethoprim/sulfamethoxazole prescribing increased (43/1,000 persons/year in 1992 to 108/1,000 persons/year in 2009, p<0.001) and non-susceptibility to trimethoprim/sulfamethoxazole in AI/AN patients ≥5 years of age increased in non-PCV7 serotypes (0–12%, p<0.05). Similarly, prescribing rates increased for macrolide antibiotics (46/1,000 persons/year in 1992 to 84/1,000 persons/year in 2009, p<0.05). We observed no statistically significant change over time in erythromycin non-susceptibility among non-PCV7 serotypes in AI/AN patients aged 5 years or greater (0–7%, p=0.087).

Conclusion

Antimicrobial prescribing patterns of some antibiotics in the AI/AN population corresponded to increased antimicrobial resistance in clinical isolates. This study highlights the on-going threat of antimicrobial resistance, the critical importance of judicious prescribing of antibiotics and the potential utility of prescribing data for addressing this issue.

Effect of the 13-valent pneumococcal conjugate vaccine on nasopharyngeal colonization by Streptococcus pneumoniae--Alaska, 2008-2012

BACKGROUND

In 2010, a 13-valent pneumococcal conjugate vaccine (PCV13) replaced a 7-valent vaccine (PCV7) that contained all PCV7 serotypes plus 6 additional serotypes (PCV6+). We conducted annual surveys from 2008 to 2012 to determine the effect of PCV13 on colonization by pneumococcal serotypes.

METHODS

We obtained nasopharyngeal swabs for pneumococcal identification and serotyping from residents of all ages at 8 rural villages and children age <60 months at 2 urban clinics. We conducted interviews/medical records review for all participants.

RESULTS

A total of 18 207 nasopharyngeal swabs (rural = 16 098; urban = 2109) were collected. From 2008 to 2012, 84% of rural and 90% of urban children age <5 years were age-appropriately vaccinated with a PCV. Overall pneumococcal colonization prevalence remained stable among rural (66%) and urban (35%) children age <5 years, and adults age ≥18 years (14%). Colonization by PCV6+ serotypes declined significantly among rural children age <5 years, urban children age <5, and adults age ≥18 over the course of the study (25%-5%, 22%-9%, 22%-6%, respectively).

CONCLUSIONS

PCV13 was rapidly introduced into the Alaska childhood immunization schedule and reduced colonization by PCV6+ serotypes among children. Unvaccinated adults also experienced comparable reductions in vaccine serotype colonization indicating substantial indirect protection from PCV13.

Haemophilus influenzae serotype a invasive disease, Alaska, USA, 1983-2011

Before introduction of Haemophilus influenzae type b (Hib) vaccines, rates of Hib disease in Alaska’s indigenous people were among the highest in the world. Vaccination reduced rates dramatically; however, invasive H. influenzae type a (Hia) disease has emerged. Cases of invasive disease were identified through Alaska statewide surveillance during1983–2011. Of 866 isolates analyzed for serotype, 32 (4%) were Hia. No Hia disease was identified before 2002; 32 cases occurred during 2002–2011 (p<0.001). Median age of case-patients was 0.7 years; 3 infants died. Incidence of Hia infection (2002–2011) among children <5 years was 5.4/100,000; 27 cases occurred in Alaska Native children (18/100,000) versus 2 cases in non-Native children (0.5/100,000) (risk ratio = 36, p<0.001). From 12/2009 to 12/2011, 15 cases of Hia disease occurred in southwestern Alaska (in children <5 years, rate = 204/100,000). Since introduction of the Hib conjugate vaccine, Hia infection has become a major invasive bacterial disease in Alaska Native children.

Migration of persons between households in rural Alaska: considerations for study design

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). 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.

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.

Increasing trend in the rate of infectious disease hospitalisations among Alaska Native people

OBJECTIVES

To examine the epidemiology of infectious disease (ID) hospitalisations among Alaska Native (AN) people.

METHODS

Hospitalisations with a first-listed ID diagnosis for American Indians and ANs residing in Alaska during 2001-2009 were selected from the Indian Health Service direct and contract health service inpatient data. ID hospitalisations to describe the general US population were selected from the Nationwide Inpatient Sample. Annual and average annual (2007-2009) hospitalization rates were calculated.

RESULTS

During 2007-2009, IDs accounted for 20% of hospitalisations among AN people. The 2007-2009 average annual age-adjusted ID hospitalisation rate (2126/100,000 persons) was higher than that for the general US population (1679/100,000; 95% CI 1639-1720). The ID hospitalisation rate for AN people increased from 2001 to 2009 (17%, p < 0.001). Although the rate during 2001-2009 declined for AN infants (< 1 year of age; p = 0.03), they had the highest 2007-2009 average annual rate (15106/100,000), which was 3 times the rate for general US infants (5215/100,000; 95% CI 4783-5647). The annual rates for the age groups 1-4, 5-19, 40-49, 50-59 and 70-79 years increased (p < 0.05). The highest 2007-2009 age-adjusted average annual ID hospitalisation rates were in the Yukon-Kuskokwim (YK) (3492/100,000) and Kotzebue (3433/100,000) regions; infant rates were 30422/100,000 and 26698/100,000 in these regions, respectively. During 2007-2009, lower respiratory tract infections accounted for 39% of all ID hospitalisations and approximately 50% of ID hospitalisations in YK, Kotzebue and Norton Sound, and 74% of infant ID hospitalisations.

CONCLUSIONS

The ID hospitalisation rate increased for AN people overall. The rate for AN people remained higher than that for the general US population, particularly in infants and in the YK and Kotzebue regions. Prevention measures to reduce ID morbidity among AN people should be increased in high-risk regions and for diseases with high hospitalisation rates.

Molecular epidemiology of serotype 19A Streptococcus pneumoniae among invasive isolates from Alaska, 1986-2010

Background

After the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in Alaska, the incidence of invasive pneumococcal disease (IPD) due to non-vaccine serotypes, particularly serotype 19A, increased. The aim of this study was to describe the molecular epidemiology of IPD due to serotype 19A in Alaska.

Methods

IPD data were collected from 1986 to 2010 through population-based laboratory surveillance. Isolates were serotyped by the Quellung reaction and MICs determined by broth microdilution. Genotypes were assessed by multilocus sequence typing.

Results

Among 3,294 cases of laboratory-confirmed IPD, 2,926 (89%) isolates were available for serotyping, of which 233 (8%) were serotype 19A. Across all ages, the proportion of IPD caused by serotype 19A increased from 3.5% (63/1823) pre-PCV7 (1986–2000) to 15.4% (170/1103) post-PCV7 (2001–2010) (p<0.001); among children <5 years of age, the proportion increased from 5.0% (39/776) to 33.0% (76/230) (p<0.001). The annual incidence rate of IPD due to serotype 19A (all ages) increased from 0.73 cases pre-PCV7 to 2.56 cases/100,000 persons post-PCV7 (p<0.001); rates among children <5 years of age increased from 4.84 cases to 14.1 cases/100,000 persons (p<0.001). Among all IPD isolates with reduced susceptibility to penicillin, 17.8% (32/180) were serotype 19A pre-PCV7 and 64% (121/189) were serotype 19A post-PCV7 (p<0.001). Eighteen different sequence types (STs) were identified; ST199 or single locus variants of ST199 (n=150) and ST172 (n=59) accounted for the majority of isolates. Multidrug-resistant isolates were clustered in ST199 and ST320.

Conclusion

While PCV13 should significantly reduce the burden of disease due to 19A, these data highlight the need to continue surveillance for IPD to monitor the effects of vaccination on the expansion and emergence of non-PCV strains.

Influenza surveillance using electronic health records in the American Indian and Alaska Native population

OBJECTIVE

Increasing use of electronic health records (EHRs) provides new opportunities for public health surveillance. During the 2009 influenza A (H1N1) virus pandemic, we developed a new EHR-based influenza-like illness (ILI) surveillance system designed to be resource sparing, rapidly scalable, and flexible. 4 weeks after the first pandemic case, ILI data from Indian Health Service (IHS) facilities were being analyzed.

MATERIALS AND METHODS

The system defines ILI as a patient visit containing either an influenza-specific International Classification of Disease, V.9 (ICD-9) code or one or more of 24 ILI-related ICD-9 codes plus a documented temperature ≥100°F. EHR-based data are uploaded nightly. To validate results, ILI visits identified by the new system were compared to ILI visits found by medical record review, and the new system's results were compared with those of the traditional US ILI Surveillance Network.

RESULTS

The system monitored ILI activity at an average of 60% of the 269 IHS electronic health databases. EHR-based surveillance detected ILI visits with a sensitivity of 96.4% and a specificity of 97.8% based on chart review (N=2375) of visits at two facilities in September 2009. At the peak of the pandemic (week 41, October 17, 2009), the median time from an ILI visit to data transmission was 6 days, with a mode of 1 day.

DISCUSSION

EHR-based ILI surveillance was accurate, timely, occurred at the majority of IHS facilities nationwide, and provided useful information for decision makers. EHRs thus offer the opportunity to transform public health surveillance.

Molecular characterization of Streptococcus pneumoniae serotype 12F isolates associated with rural community outbreaks in Alaska

Outbreaks of invasive pneumococcal disease (IPD) caused by Streptococcus pneumoniae serotype 12F were observed in two neighboring regions of rural Alaska in 2003 to 2006 and 2006 to 2008. IPD surveillance data from 1986 to 2009 and carriage survey data from 1998 to 2004 and 2008 to 2009 were reviewed to identify patterns of serotype 12F transmission. Pulsed-field gel electrophoresis was performed on all available isolates, and selected isolates were characterized by additional genetic subtyping methods. Serotype 12F IPD occurred in two waves in Alaska between 1986 and 2008. While cases of disease occurred nearly every year in Anchorage, in rural regions, 12F IPD occurred with rates 10- to 20-fold higher than those in Anchorage, often with many years between disease peaks and generally caused by a single predominant genetic clone. Carriage occurred predominantly in adults, except early in the rural outbreaks, when most carriage was in persons <18 years old. In rural regions, carriage of 12F disappeared completely after outbreaks. Different 12F clones appear to have been introduced episodically into rural populations, spread widely in young, immunologically naïve populations (leading to outbreaks of IPD lasting 1 to 3 years), and then disappeared rapidly from the population. Larger population centers might have been the reservoir for these clones. This epidemiologic pattern is consistent with a highly virulent, but immunogenic, form of pneumococcus.

Duration of protection against hepatitis A for the current two-dose vaccine compared to a three-dose vaccine schedule in children

BACKGROUND

Hepatitis A is mostly a self-limiting disease but causes substantial economic burden. Consequently, United States Advisory Committee for Immunization Practices recommends inactivated hepatitis A vaccination for all children beginning at age 1 year and for high risk adults. The hepatitis A vaccine is highly effective but the duration of protection is unknown.

METHODS

We examined the proportion of children with protective hepatitis A antibody levels (anti-HAV ≥20 mIU/mL) as well as the geometric mean concentration (GMC) of anti-HAV in a cross sectional convenience sample of individuals aged 12-24 years, who had been vaccinated with a two-dose schedule in childhood, with the initial dose at least 5 years ago. We compared a subset of data from persons vaccinated with two-doses (720 EL.U.) at age 3-6 years with a demographically similar prospective cohort that received a three-dose (360 EL.U.) schedule and have been followed for 17 years.

RESULTS

No significant differences were observed when comparing GMC between the two cohorts at 10 (P=0.467), 12 (P=0.496), and 14 (P=0.175) years post-immunization. For the three-dose cohort, protective antibody levels remain for 17 years and have leveled-off over the past 7 years.

CONCLUSION

The two- and three-dose schedules provide similar protection >14 years after vaccination, indicating a booster dose is not needed at this time. Plateauing anti-HAV GMC levels suggest protective antibody levels may persist long-term.

Long-term immunogenicity of hepatitis A virus vaccine in Alaska 17 years after initial childhood series

The Centers for Disease Control and Prevention recommends hepatitis A virus (HAV) vaccination for all children at age 1 year and for high-risk adults. The vaccine is highly effective; however, protection duration is unknown. We report HAV antibody concentrations 17 years after childhood immunization, demonstrating that protective antibody levels remain and have stabilized over the past 7 years.

Modeling insights into Haemophilus influenzae type b disease, transmission, and vaccine programs

Flexible simulation model use can optimize vaccination programs and response to changes in vaccine supply.

In response to the 2007–2009 Haemophilus influenzae type b (Hib) vaccine shortage in the United States, we developed a flexible model of Hib transmission and disease for optimizing Hib vaccine programs in diverse populations and situations. The model classifies population members by age, colonization/disease status, and antibody levels, with movement across categories defined by differential equations. We implemented the model for the United States as a whole, England and Wales, and the Alaska Native population. This model accurately simulated Hib incidence in all 3 populations, including the increased incidence in England/Wales beginning in 1999 and the change in Hib incidence in Alaska Natives after switching Hib vaccines in 1996. The model suggests that a vaccine shortage requiring deferral of the booster dose could last 3 years in the United States before loss of herd immunity would result in increasing rates of invasive Hib disease in children <5 years of age.

Treatment eligibility in Alaska Native and American Indian persons with hepatitis C virus infection

Objectives

Treatment with pegylated interferon and ribavirin may prevent progression of liver disease among patients with chronic hepatitis C virus infection (HCV). Treatment initiation is based on published clinical eligibility criteria, patients’ willingness to undergo treatment and likelihood of success. We examined treatment eligibility in a cohort of Alaska Native and American Indian persons with chronic HCV infection.

Study design

Retrospective cohort study.

Methods

Medical records of all treatment naïve HCV RNA positive patients given an appointment by hepatology specialty clinic staff in 2003 and 2007 were evaluated by a hepatology provider to investigate documented reasons for treatment deferral.

Results

Treatment was initiated in 4 of 94 patients (4%) in 2003 and 14 of 146 patients (10%) in 2007. Major reasons for treatment deferral in 2003 versus 2007 included inconsistent appointment attendance (36% of deferrals vs. 18%), active substance abuse (17% vs. 22%), patient decision (17% vs. 27%), liver biopsy without fibrosis or normal ALT (8% vs. 3%), uncontrolled psychiatric condition (7% vs. 7%) and concurrent medical condition (6% vs. 9%). There was significant improvement in proportion of appointments attended in 2007 versus 2003 (76% vs. 67%, p =0.04) and the percentage of patients attending at least 1 appointment (84% vs. 66%, p=0.002).

Conclusions

Multiple reasons for treatment deferral were documented. Despite a significant improvement in hepatology clinic attendance and an increase in the number of patients started on treatment in 2007 compared to 2003, the overall percentage of those treated remained low.

Diagnostic accuracy of tests for Helicobacter pylori in an Alaska Native population

AIM: To evaluate the accuracy of two non-invasive tests in a population of Alaska Native persons. High rates of Helicobacter pylori (H. pylori) infection, H. pylori treatment failure, and gastric cancer in this population necessitate documentation of infection status at multiple time points over a patient’s life.

METHODS: In 280 patients undergoing endoscopy, H. pylori was diagnosed by culture, histology, rapid urease test, ¹³C urea breath test (UBT), and immunoglobulin G antibodies to H. pylori in serum. The performances of ¹³C-UBT and antibody test were compared to a gold standard defined by a positive H. pylori test by culture or, in case of a negative culture result, by positive histology and a positive rapid urease test.

RESULTS: The sensitivity and specificity of the ¹³C-UBT were 93% and 88%, respectively, relative to the gold standard. The antibody test had an equivalent sensitivity of 93% with a reduced specificity of 68%. The false positive results for the antibody test were associated with previous treatment for an H. pylori infection [relative risk (RR) = 2.8]. High levels of antibodies to H. pylori were associated with chronic gastritis and male gender, while high scores in the ¹³C-UBT test were associated with older age and with the H. pylori bacteria load on histological examination (RR = 4.4).

CONCLUSION: The ¹³C-UBT outperformed the antibody test for H. pylori and could be used when a non-invasive test is clinically necessary to document treatment outcome or when monitoring for reinfection.

2009 Pandemic influenza A H1N1 in Alaska: temporal and geographic characteristics of spread and increased risk of hospitalization among Alaska Native and Asian/Pacific Islander people

Alaska Native people have suffered disproportionately from previous influenza pandemics. We evaluated 3 separate syndromic data sources to determine temporal and geographic patterns of spread of 2009 pandemic influenza A H1N1 (pH1N1) in Alaska, and reviewed records from persons hospitalized with pH1N1 disease in 3 areas in Alaska to characterize clinical and epidemiologic features of disease in Alaskans. A wave of pH1N1 disease swept through Alaska beginning in most areas in August or early September. In rural regions, where Alaska Native people comprise a substantial proportion of the population, disease occurred earlier than in other regions. Alaska Native people and Asian/Pacific Islanders (A/PI) were 2-4 times more likely to be hospitalized than whites. Alaska Native people and other minorities remain at high risk for early and substantial morbidity from pandemic influenza episodes. These findings should be integrated into plans for distribution and use of vaccine and antiviral agents.