Incidence and prevalence of Parkinson's disease among Navajo people living in the Navajo nation.

Parkinson's disease (PD) is largely unstudied among American Indians. Unique populations might harbor clues to elusive causes. We describe the incidence and prevalence of PD among Navajo people residing in the Navajo Nation, home to the largest American Indian tribe in the United States. We analyzed 2001-2011 inpatient and outpatient visit data for Navajo people obtained from the Indian Health Service, which provides health care to American Indian people living on the Navajo Reservation. Cases were defined by at least two inpatient or outpatient visits with the diagnosis of PD. Crude and age-adjusted incidence and prevalence rates were calculated overall as well as by age, sex, region of residence, and time period. Five hundred twenty-four Navajo people with median age-at-onset of 74.0 years were diagnosed with PD during the study period, yielding an average annual crude incidence rate of 22.5/100,000. Age-specific incidence was 232.0 for patients 65 years of age or older and 302.0 for 80 years of age or older. Age-adjusted incidence was 35.9 overall (238.1 for ≥65 years), was higher in men than in women (47.5 vs. 27.7; P<0.001), varied by region (P=0.03), and was similar between time periods (2002-2004 vs. 2009-2011). The age-adjusted point prevalence rate was 261.0. The rate of PD among Navajo People appears to be as high as or higher than rates reported in many other populations. Rates increased to the highest age group, consistent with population-based studies. Further investigation is warranted to examine risk factors for PD in this remote population.

Effect of rapid influenza diagnostic testing on antiviral treatment decisions for patients with influenza-like illness: southwestern U.S., May-December 2009.

Rapid influenza diagnostic tests (RIDTs) had low test sensitivity for detecting 2009 pandemic influenza A (H1N1pdm09) infection, causing public health authorities to recommend that treatment decisions be based primarily upon risk for influenza complications. We used multivariate Poisson regression analysis to estimate the contribution of RIDT results and risk for H1N1pdm09 complications to receipt of early antiviral (AV) treatment among 290 people with influenza-like illness (ILI) who received an RIDT ≤48 hours after symptom onset from May to December 2009 at four southwestern U.S. facilities. RIDT results had a stronger association with receipt of early AVs (rate ratio [RR] = 3.3, 95% confidence interval [CI] 2.4, 4.6) than did the presence of risk factors for H1N1pdm09 complications (age <5 years or high-risk medical conditions) (RR=1.9, 95% CI 1.3, 2.7). Few at-risk people (28/126, 22%) who had a negative RIDT received early AVs, suggesting the need for sustained efforts by public health to influence clinician practices.

Understanding the burden of tuberculosis among American Indians/Alaska Natives in the U.S.: a validation study.

OBJECTIVE: We validated cases of active tuberculosis (TB) recorded in the Indian Health Service (IHS) National Patient Information Reporting System (NPIRS) and evaluated the completeness of TB case reporting from IHS facilities to state health departments. METHODS: We reviewed the medical records of American Indian/Alaska Native (AI/AN) patients at IHS health facilities who were classified as having active TB using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnostic codes from 2006 to 2009 for clinical and laboratory evidence of TB disease. Individuals were reclassified as having active TB disease; recent latent TB infection (LTBI); past positive tuberculin skin test (TST) only; or as having no evidence of TB, LTBI, or a past positive TST. We compared validated active TB cases with corresponding state records to determine if they were reported. RESULTS: The study included 596 patients with active TB as per ICD-9-CM codes. Based on chart review, 111 (18.6%) had active TB; 156 (26.2%) had LTBI; 104 (17.4%) had a past positive TST; and 221 (37.1%) had no evidence of TB disease, LTBI, or a past positive TST. Of the 111 confirmed cases of active TB, 89 (80.2%) resided in participating states; 81 of 89 (91.2%) were verified as reported TB cases. CONCLUSIONS: ICD-9-CM codes for active TB disease in the IHS NPIRS do not accurately reflect the burden of TB among AI/ANs. Most confirmed active TB cases in the IHS health system were reported to the state; the national TB surveillance system may accurately represent the burden of TB in the AI/AN population.

Molluscum contagiosum in a pediatric American Indian population: incidence and risk factors.

BACKGROUND: Molluscum contagiosum virus (MCV) causes an innocuous yet persistent skin infection in immunocompetent individuals and is spread by contact with lesions. Studies point to atopic dermatitis (AD) as a risk factor for MCV infection; however, there are no longitudinal studies that have evaluated this hypothesis. METHODS: Outpatient visit data from fiscal years 2001-2009 for American Indian and Alaska Native (AI/AN) children were examined to describe the incidence of molluscum contagiosum (MC). We conducted a case-control study of patients <5 years old at an Indian Health Service (IHS) clinic to evaluate dermatological risk factors for infection. RESULTS: The incidence rate for MC in children <5 years old was highest in the West and East regions. MC cases were more likely to have a prior or co-occurring diagnosis of eczema, eczema or dermatitis, impetigo, and scabies (p<0.05) compared to controls; 51.4% of MC cases had a prior or co-occurring diagnosis of eczema or dermatitis. CONCLUSIONS: The present study is the first demonstration of an association between AD and MC using a case-control study design. It is unknown if the concurrent high incidence of eczema and MC is related, and this association deserves further investigation.

American Indian and Alaska Native infant and pediatric mortality, United States, 1999-2009.

OBJECTIVES: We described American Indian/Alaska Native (AI/AN) infant and pediatric death rates and leading causes of death. METHODS: We adjusted National Vital Statistics System mortality data for AI/AN racial misclassification by linkage with Indian Health Service (IHS) registration records. We determined average annual death rates and leading causes of death for 1999 to 2009 for AI/AN versus White infants and children. We limited the analysis to IHS Contract Health Service Delivery Area counties. RESULTS: The AI/AN infant death rate was 914 (rate ratio [RR] = 1.61; 95% confidence interval [CI] = 1.55, 1.67). Sudden infant death syndrome, unintentional injuries, and influenza or pneumonia were more common in AI/AN versus White infants. The overall AI/AN pediatric death rates were 69.6 for ages 1 to 4 years (RR = 2.56; 95% CI = 2.38, 2.75), 28.9 for ages 5 to 9 years (RR = 2.12; 95% CI = 1.92, 2.34), 37.3 for ages 10 to 14 years (RR = 2.22; 95% CI = 2.04, 2.40), and 158.4 for ages 15 to 19 years (RR = 2.71; 95% CI = 2.60, 2.82). Unintentional injuries and suicide occurred at higher rates among AI/AN youths versus White youths. CONCLUSIONS: Death rates for AI/AN infants and children were higher than for Whites, with regional disparities. Several leading causes of death in the AI/AN pediatric population are potentially preventable.

Pneumonia and influenza mortality among American Indian and Alaska Native people, 1990-2009.

OBJECTIVES: We compared pneumonia and influenza death rates among American Indian/Alaska Native (AI/AN) people with rates among Whites and examined geographic differences in pneumonia and influenza death rates for AI/AN persons. METHODS: We adjusted National Vital Statistics Surveillance mortality data for racial misclassification of AI/AN people through linkages with Indian Health Service (IHS) registration records. Pneumonia and influenza deaths were defined as those who died from 1990 through 1998 and 1999 through 2009 according to codes for pneumonia and influenza from the International Classification of Diseases, 9th and 10th Revision, respectively. We limited the analysis to IHS Contract Health Service Delivery Area counties, and compared pneumonia and influenza death rates between AI/ANs and Whites by calculating rate ratios for the 2 periods. RESULTS: Compared with Whites, the pneumonia and influenza death rate for AI/AN persons in both periods was significantly higher. AI/AN populations in the Alaska, Northern Plains, and Southwest regions had rates more than 2 times higher than those of Whites. The pneumonia and influenza death rate for AI/AN populations decreased from 39.6 in 1999 to 2003 to 33.9 in 2004 to 2009. CONCLUSIONS: Although progress has been made in reducing pneumonia and influenza mortality, disparities between AI/AN persons and Whites persist. Strategies to improve vaccination coverage and address risk factors that contribute to pneumonia and influenza mortality are needed.

Infectious disease mortality among American Indians and Alaska Natives, 1999-2009.

OBJECTIVES: We described death rates and leading causes of death caused by infectious diseases (IDs) in American Indian/Alaska Native (AI/AN) persons. Methods. We analyzed national mortality data, adjusted for AI/AN race by linkage with Indian Health Service registration records, for all US counties and Contract Health Service Delivery Area (CHSDA) counties. The average annual 1999 to 2009 ID death rates per 100,000 persons for AI/AN persons were compared with corresponding rates for Whites. RESULTS: The ID death rate in AI/AN populations was significantly higher than that of Whites. A reported 8429 ID deaths (rate 86.2) in CHSDA counties occurred among AI/AN persons; the rate was significantly higher than the rate in Whites (44.0; rate ratio [RR] = 1.96; 95% confidence interval [CI] = 1.91, 2.00). The rates for the top 10 ID underlying causes of death were significantly higher for AI/AN persons than those for Whites. Lower respiratory tract infection and septicemia were the top-ranked causes. The greatest relative rate disparity was for tuberculosis (RR = 13.51; 95% CI = 11.36, 15.93). CONCLUSIONS: Health equity might be furthered by expansion of interventions to reduce IDs among AI/AN communities.

Encephalitis-associated hospitalizations among American Indians and Alaska Natives.

Encephalitis produces considerable morbidity in the United States, but morbidity rates among American Indian/Alaska Native (AI/AN) people have not been described. Hospitalization records listing an encephalitis diagnosis were analyzed by using Indian Health Service direct/contract inpatient data. For 1998-2010, there were 436 encephalitis-associated hospitalizations among AI/AN people, an average annual age-adjusted hospitalization rate of 3.1/100,000 population. The rate for infants (11.9) was more than double that for any other age group. Death occurred for 4.1% of hospitalizations. Consistent with reports for the general U.S. population, the rate was high among infants and most (53.9%) hospitalizations were of unexplained etiology. The average annual rate during the study period appeared lower than for the general U.S. population, due particularly to lower rates in the elderly. Future community-based surveillance and mortality studies are needed to confirm these findings and examine reasons underlying the low rates of encephalitis in AI/AN people.

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.

Severe acute respiratory infections caused by 2009 pandemic influenza A (H1N1) among American Indians--southwestern United States, May 1-July 21, 2009.

BACKGROUND: During April-July 2009, U.S. hospitalization rates for 2009 pandemic influenza A (H1N1) virus (H1N1pdm09) infection were estimated at 4·5/100 000 persons. We describe rates and risk factors for H1N1pdm09 infection among American Indians (AIs) in four isolated southwestern U.S. communities served by the Indian Health Service (IHS). METHODS: We reviewed clinical and demographic information from medical records of AIs hospitalized during May 1-July 21, 2009 with severe acute respiratory infection (SARI). Hospitalization rates were determined using denominator data provided by IHS. H1N1pdm09 infection was confirmed with polymerase chain reaction, rapid tests, or convalescent serology. Risk factors for more severe (SARI) versus milder [influenza-like illness (ILI)] illness were determined by comparing confirmed SARI patients with outpatients with ILI. RESULTS: Among 168 SARI-hospitalized patients, 52% had confirmed H1N1pdm09 infection and 93% had >1 high-risk condition for influenza complications. The H1N1pdm09 SARI hospitalization rate was 131/100 000 persons [95% confidence interval (CI), 102-160] and was highest among ages 0-4 years (353/100 000; 95% CI, 215-492). Among children, asthma (adjusted odds ratio [aOR] 3·2; 95% CI, 1·2-8·4) and age<2 years (aOR 3·8; 95% CI, 1·4-10·0) were associated with H1N1pdm09 SARI-associated hospitalization, compared with outpatient ILI. Among adults, diabetes (aOR 3·1; 95% CI, 1·5-6·4) was associated with hospitalization after controlling for obesity. CONCLUSIONS: H1N1pdm09 hospitalization rates among this isolated AI population were higher than reported for other U.S. populations. Almost all case patients had high-risk health conditions. Prevention strategies for future pandemics should prioritize AIs, particularly in isolated rural areas.

Incidence of amyotrophic lateral sclerosis among American Indians and Alaska natives.

IMPORTANCE: More thorough evaluation of amyotrophic lateral sclerosis (ALS) and motor neuron disease in unique populations could provide clues to etiologies for these idiopathic conditions, and educational programs for American Indian and Alaska Native (AI/AN) people and health care professionals on reservations could improve awareness, understanding, diagnosis, and treatment. In the ongoing search for susceptibility genes, studying particular racial groups, such as AI/ANs,might facilitate the identification of new mutations. OBJECTIVE: To provide better understanding of ALS and secondarily of motor neuron disease among AI/AN people by estimating the incidence and prevalence among AI/ANs served by the Indian Health Service health care system. DESIGN AND SETTING: Analysis of electronic records for AI/ANs with ALS and with motor neuron disease separately for the calendar years 2002-2009 using inpatient and outpatient visit data from the Indian Health Service, which provides health care to eligible AI/ANs nationwide. PARTICIPANTS: Cases were defined by at least 2 inpatient or outpatient visits with the diagnosis. MAIN OUTCOME MEASURES: Crude and age-adjusted incidence and prevalence rates were calculated. RESULTS: Seventy-one AI/ANs were diagnosed with ALS, yielding an average annual crude incidence rate of 0.63 cases per 100 000 and an age-adjusted incidence of 0.92. The median age at onset was 56.0 years and was higher among women than men (62.0 vs 55.0 years; P=.06). Age-specific incidence increased to 70 to 74 years. The crude and age-adjusted point prevalence rates were 2.00 and 4.12, respectively. The crude and age-adjusted incidence rates for motor neuron disease were 1.08 and 1.50, respectively. The annual rates were unchanged across the study period. CONCLUSIONS AND RELEVANCE: The incidence of ALS among AI/ANs appears to be lower than that reported for white populations, a finding congruent with reports of other minority populations. Community-based studies are important to confirm these findings and to examine reasons for the low rate of ALS among AI/ANs.

Dog bite injuries among American Indian and Alaska Native children.

OBJECTIVE: To examine dog bites among American Indian (AI) and Alaska Native (AN) children visiting Indian Health Service and tribal health facilities. STUDY DESIGN: We retrospectively analyzed hospitalizations and outpatient visits with a diagnosis of dog bite between 2001 and 2008 in AI/AN children aged <20 years. Rates of dog bite hospitalizations and outpatient visits were estimated by age group, sex, region, and number and location of open wounds using Indian Health Service data. Analyses of hospitalizations for the general US population aged<20 years used the Nationwide Inpatient Sample. RESULTS: The average annual dog bite hospitalization rate was higher among AI/AN children in Alaska (6.1/100,000 population) and the Southwest region (5.3/100,000) compared with the general US child population (3.1/100,000; 95% CI, 2.9-3.3/100,000). The average annual outpatient visit rate in AI/AN children was highest in the Alaska (596.4/100,000), Southwest (540.0/100,000), and Northern Plains West (537.6/100,000) regions. The hospitalization rate was highest in both AI/AN and US males aged<5 years, and outpatient visit rates were highest in AI/AN males aged 5-9 years. Open wounds diagnoses were most commonly seen on the head, neck, and face in hospitalized children (45.5% of open wounds in AI/AN children, 59.3% in US children; SE, 1.0%) and on the leg in AI/AN outpatients (35.6%). CONCLUSION: Dog bites represent a significant public health threat in AI/AN children in the Alaska, the Southwest, and Northern Plains West regions of the US. Enhanced animal control and education efforts should reduce dog bite injuries and associated problems with pets and stray dogs, such as emerging infectious diseases.

Parkinson's disease among American Indians and Alaska natives: a nationwide prevalence study.

BACKGROUND: The objective of this study was to determine the prevalence of Parkinson's disease (PD) among American Indian and Alaska Native (AI/AN) people. METHODS: We analyzed records for AI/AN people between 2002 and 2009 using inpatient and outpatient visit data from the Indian Health Service. Crude and age-adjusted prevalence, using the 2000 projected US population as the standard, was determined overall and by age group, sex, period, and region. RESULTS: An estimated 2613 AI/AN people carried the diagnosis of PD (crude prevalence, 143.8/100,000). Prevalence increased with age through 84 years. The age-adjusted rate was 355.7 and was higher among men than women (P < .0001). Rates differed by region (P < .0001). CONCLUSIONS: Parkinson's disease is prevalent among AI/AN people. The prevalence increases with age, varies by geographic region, and is higher among men than women. Community-based studies are needed to define incidence, examine risk factors, and determine reasons for sex and regional differences in PD among AI/AN people.

Epidemiology of ehrlichiosis and anaplasmosis among American Indians in the United States, 2000-2007.

Ehrlichiosis and anaplasmosis infections among American Indians (AIs) have never been specifically examined, despite high rates of other tick-borne rickettsial diseases among AIs. The epidemiology of ehrlichiosis and anaplasmosis among AIs was analyzed using the National Electronic Telecommunications System for Surveillance (NETSS), Case Report Forms (CRFs), and Indian Health Service (IHS) inpatient and outpatient visits. The 2000-2007 average annual ehrlichiosis and anaplasmosis incidence among AIs reported to NETSS was almost 4-fold lower (4.0/1,000,000) than that using IHS data (14.9). American Indian cases reported from CRFs had a higher proportion of hospitalization (44%) compared with IHS (10%). American Indian incidence of ehrlichiosis and anaplasmosis was higher and showed a different age and geographical distribution than other races. These results highlight the need to improve collaboration between the ehrlichiosis and anaplasmosis surveillance systems for AIs so as to develop interventions that target the unique epidemiology and mitigate the burden of disease among this high-risk population.

Impact of rotavirus vaccine on diarrhea-associated disease burden among American Indian and Alaska Native children.

OBJECTIVE: Beginning in 2006, the Indian Health Service (IHS) began rotavirus vaccination of American Indian and Alaska Native (AI/AN) infants. To assess vaccine impact, we examined trends in IHS diarrhea-associated hospitalization and outpatient visits among AI/AN children in the pre- and postrotavirus vaccine era. METHODS: Diarrhea-associated hospitalizations and outpatient visits among AI/AN children <5 years of age during 2001 through 2010 were examined by gender, age group, and region for prevaccine years 2001-2006 and postvaccine years 2008, 2009, and 2010. To account for secular declining trends observed in prevaccine years, expected diarrhea-associated hospitalization and outpatient rates for postvaccine years were generated by using Poisson regression analysis of the 2001-2006 annual rates. RESULTS: Coverage with at least 1 dose of rotavirus vaccine among AI/AN infants aged 3 to 5 months in the first half of 2008, 2009, and 2010 ranged from 48% to 80% in various IHS regions. The prevaccine average annual diarrhea-associated hospitalization rates among AI/AN children <5 years of age was 63 per 10 000 persons (range: 57-75 per 10 000), and declined to 39, 31, and 27 per 10 000 in 2008, 2009, and 2010, respectively. Observed 2008, 2009, and 2010 rates were 24%, 37%, and 44% lower than expected rates, respectively. Decreases in diarrhea-associated hospitalizations and outpatient visits were observed in all IHS regions. CONCLUSIONS: Diarrhea-associated hospitalization and outpatient visit rates among AI/AN children have declined after implementation of rotavirus vaccination in AI/AN populations.

Outbreak of lower respiratory tract illness associated with human enterovirus 68 among American Indian children.

Human enterovirus 68 (EV68) infections are rarely reported. We describe a respiratory outbreak associated with EV68 among 18 children admitted to a remote Indian Health Service facility during August 11, 2010 through September 14, 2010. Clinical illness was characterized by pneumonia and wheezing. EV68 should be considered as an etiology in outbreaks of lower respiratory tract illness.

Trends in clinical diagnoses of Rocky Mountain spotted fever among American Indians, 2001-2008.

American Indians are at greater risk for Rocky Mountain spotted fever (RMSF) than the general U.S. population. The epidemiology of RMSF among American Indians was examined by using Indian Health Service inpatient and outpatient records with an RMSF International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis. For 2001-2008, 958 American Indian patients with clinical diagnoses of RMSF were reported. The average annual RMSF incidence was 94.6 per 1,000,000 persons, with a significant increasing incidence trend from 24.2 in 2001 to 139.4 in 2008 (P = 0.006). Most (89%) RMSF hospital visits occurred in the Southern Plains and Southwest regions, where the average annual incidence rates were 277.2 and 49.4, respectively. Only the Southwest region had a significant increasing incidence trend (P = 0.005), likely linked to the emergence of brown dog ticks as an RMSF vector in eastern Arizona. It is important to continue monitoring RMSF infection to inform public health interventions that target RMSF reduction in high-risk populations.

Epidemic assistance from the Centers for Disease Control and Prevention involving American Indians and Alaska Natives, 1946-2005.

The authors describe 169 Centers for Disease Control and Prevention epidemic-assistance investigations involving American Indians and Alaska Natives that occurred during 1946-2005. The unique relation between the US federal government and American Indian and Alaska Native tribes is described in the context of transfer in the 1950s of responsibility for Indian health to the US Public Health Service, which at the time included the Communicable Disease Center, the Centers for Disease Control and Prevention's precursor. The vast majority of epidemic-assistance investigations were for infectious disease outbreaks (86%), with a relatively limited number, since 1980 only, involving environmental exposures and chronic disease. Although outbreaks investigated were often widespread geographically, the majority were limited in scope, typically involving fewer than 100 patients. Epidemic-assistance investigations for hepatitis A, gastrointestinal and foodborne infectious diseases, vaccine-preventable diseases, zoonotic and vectorborne diseases, acute respiratory tract infections, environmental exposures, and chronic diseases are described chronologically in more detail.

Changing trends in viral hepatitis-associated hospitalizations in the American Indian/Alaska Native population, 1995-2007.

OBJECTIVE: We described the changing epidemiology of viral hepatitis among the American Indian/Alaska Native (AI/AN) population that uses Indian Health Service (IHS) health care. METHODS: We used hospital discharge data from the IHS National Patient Information Reporting System to determine rates of hepatitis A-, B-, and C-associated hospitalization among AI/ANs using IHS health care from 1995-2007 and summary periods 1995-1997 and 2005-2007. RESULTS: Hepatitis A-associated hospitalization rates among AI/AN people decreased from 4.9 per 100,000 population during 1995-1997 to 0.8 per 100,000 population during 2005-2007 (risk ratio [RR] = 0.2, 95% confidence interval [CI] 0.1, 0.2). While there was no significant change in the overall hepatitis B-associated hospitalization rate between time periods, the average annual rate in people aged 45-64 years increased by 109% (RR=2.1, 95% CI 1.4, 3.2). Between the two time periods, the hepatitis C-associated hospitalization rate rose from 13.0 to 55.0 per 100,000 population (RR=4.2, 95% CI 3.8, 4.7), an increase of 323%. The hepatitis C-associated hospitalization rate was highest among people aged 45-64 years, males, and those in the Alaska region. CONCLUSIONS: Hepatitis A has decreased to near-eradication levels among the AI/AN population using IHS health care. Hepatitis C-associated hospitalizations increased significantly; however, there was no significant change in hepatitis B-associated hospitalizations. Emphasis should be placed on continued universal childhood and adolescent hepatitis B vaccination and improved vaccination of high-risk adults. Prevention and education efforts should focus on decreasing hepatitis C risk behaviors and identifying people with hepatitis C infection so they may be referred for treatment.