Eight years of Legionnaires' disease transmission in travellers to a condominium complex in Las Vegas, Nevada.

Travel is a risk factor for Legionnaires' disease. In 2008, two cases were reported in condominium guests where we investigated a 2001 outbreak. We reinvestigated to identify additional cases and determine whether ongoing transmission resulted from persistent colonization of potable water. Exposures were assessed by matched case-control analyses (2001) and case-series interviews (2008). We sampled potable water and other water sources. Isolates were compared using sequence-based typing. From 2001 to 2008, 35 cases were identified. Confirmed cases reported after the cluster in 2001-2002 were initially considered sporadic, but retrospective case-finding identified five additional cases. Cases were more likely than controls to stay in tower 2 of the condominium [matched odds ratio (mOR) 6·1, 95% confidence interval (CI) 1·6-22·9]; transmission was associated with showering duration (mOR 23·0, 95% CI 1·4-384). We characterized a clinical isolate as sequence type 35 (ST35) and detected ST35 in samples of tower 2's potable water in 2001, 2002, and 2008. This prolonged outbreak illustrates the importance of striving for permanent Legionella eradication from potable water.

Suspected transmission of norovirus in eight long-term care facilities attributed to staff working at multiple institutions.

This study reports on gastroenteritis outbreaks suspected of being norovirus infections in eight long-term care facilities. A descriptive epidemiological investigation was used to depict sources of infections and control measures. Outbreaks affected 299 (31%) of 954 residents and 95 (11%) of 843 staff. Attack rates were higher in residents (range 17-55%) than staff (range 3-35%). Person-to-person spread was suspected. The case-hospitalization rate was 2·5%, and no death occurred. Eight staff members were employed at multiple affected facilities and may have introduced disease into three facilities. Thirty-two stool specimens were positive for norovirus by real-time reverse transcriptase-polymerase chain reaction or enzyme immunoassay. Sequenced specimens were closely related to GII.4 New Orleans. A concurrent Clostridium difficile outbreak was also detected at one facility. Staff members who work at multiple facilities may transmit norovirus between them. Regulatory agencies should consider precluding ill staff from working in multiple facilities during outbreaks. Guidelines to control norovirus must be applied promptly and meticulously by facilities.

Injuries associated with snowmobiles, Alaska, 1993-1994.

OBJECTIVE: To characterize the nature and burden of snowmobile injuries in Alaska by examining injury deaths and hospitalizations associated with snowmobiles and comparing these with injury deaths and hospitalizations associated with on-road motor vehicles. METHODS: The authors used vital statistics, medical examiner, Department of Public Safety, and Department of Transportation records to identify snowmobile injury deaths, and used vital statistics mortality files to identify on-road motor vehicle injury deaths. The Alaska Trauma Registry provided data on hospitalizations. The number of vehicles in use in 1993-1994 was estimated from snowmobile sales and on-road motor vehicle registrations. RESULTS: For 1993-1994, injury death and hospitalization rates were greater for snowmobiles than for on-road motor vehicles. In northern Alaska, snowmobile injuries outnumbered on-road motor vehicle injuries. A total of 26 snowmobile injury deaths were reported; 7 decedents drowned after breaking through ice and 8 were ejected from vehicles. More than half (58%) of the snowmobile injury deaths involved a natural object such as a boulder, ravine, or river. Of the 17 decedents for whom blood alcohol concentrations were available, 11 (65%) had blood alcohol concentrations > or = 100 mg/dL. CONCLUSIONS: Natural obstacles and alcohol intoxication contribute to the high risk of injury death associated with snowmobile use. Injury control strategies, including trail development and improvement, should be evaluated.

Trace metals in ancient hair from the Karluk Archaeological Site, Kodiak, Alaska.

Considerable interest exists in characterizing the extent of changes in methylmercury exposures from preindustrial to modern-day times. Hair is often preserved over centuries and has been useful in determining the extent of dietary trace metal exposures, particularly methylmercury. We examined 16 human hair samples taken from human hair bundles buried in the soil of the Karluk One Archaeological site located near the current Karluk village on the Kodiak Archipelago of Alaska. Hair samples were analyzed for total mercury, methylmercury, selenium, and cadmium. The mean total mercury level was 1.33 ppm (SD = 1.09). The mean methylmercury level, however, was considerably lower than the total mercury concentration: the mean methylmercury level was 0.03 ppm (SD = 0.02). The mean cadmium level was 0.15 ppm (SD = 0.14) and the mean selenium level was 5.22 ppm (SD = 5.73). While the concentration of total mercury in the Karluk hair samples is comparable to those observed in ancient hair from other locations, direct methylmercury quantization demonstrated that methylmercury levels were less than 2% of the total mercury in these hair samples. Because the hair was subjected to a variety of environmental influences over the centuries, the possibility of degradation of methylmercury in the hair over the last 400 to 800 years cannot be ruled out. The use of hair from remains found in more protected frozen or dry environments may provide the best evidence for the extent of preindustrial exposures to methylmercury and other trace metals.

Measles outbreak in Juneau, Alaska, 1996: implications for future outbreak control strategies.

OBJECTIVE: To determine the most effective outbreak control strategy for school-based measles outbreaks as the proportion of children with two doses of measles-containing vaccine (MCV) increases. SETTING: A school-based measles outbreak during 1996 involving 63 cases in Juneau, Alaska (population 29 288), where systematic revaccination with MCV was not implemented. DESIGN: A retrospective evaluation using chain-of-transmission data of three possible outbreak control strategies: no school revaccination, targeted school revaccination (affected schools only), and community-wide school revaccination (all schools). Two-dose MCV coverage among students was estimated from school vaccination records and a survey issued to parents. PRIMARY OUTCOME MEASURES: Potentially preventable cases of measles and doses of MCV administered per case prevented. RESULTS: Two-dose MCV coverage among Juneau students was estimated to be 44% and 53% immediately before and after the outbreak, respectively. Of all the measles cases, an estimated 24 to 28 and 27 to 31 were potentially preventable by the targeted and community-wide school revaccination strategies, respectively. Either strategy might have optimally decreased the outbreak duration by 1 month, sparing one of seven affected schools and 10 of 12 unvaccinated children who had measles. Approximately 133 to 155 and 139 to 160 doses of MCV per case prevented would have been required for targeted and community-wide school revaccination, respectively. CONCLUSIONS: Either targeted or community-wide school revaccination would have been effective control strategies for this outbreak. Targeted school revaccination is probably the intervention of choice for school-based measles outbreaks in larger communities with higher two-dose MCV coverage. As two-dose MCV coverage continues to increase in the United States, public health control measures to respond to outbreaks need to be reevaluated.

Confirmed previous infection with Chlamydia pneumoniae (TWAR) and its presence in early coronary atherosclerosis.

BACKGROUND: Chlamydia pneumoniae has been identified in coronary atheroma, but concomitant serum antibody titers have been inconsistently positive and unavailable before the detection of early or advanced atherosclerotic lesions. METHODS AND RESULTS: This retrospective investigation was performed on premortem serum specimens and autopsy tissue from 60 indigenous Alaska Natives at low risk for coronary heart disease, selected by the potential availability of their stored specimens. Serum specimens were drawn a mean of 8.8 years (range, 0.7 to 26.2 years) before death, which occurred at a mean age of 34.1 years (range, 15 to 57 years), primarily from noncardiovascular causes (97%). Coronary artery tissues were independently examined histologically and, for C pneumoniae organism and DNA, by immunocytochemistry (ICC) and polymerase chain reaction (PCR) with species-specific monoclonal antibody and primers. Microimmunofluorescence detected species-specific IgG, IgA, and IgM antibody in stored serum. C pneumoniae, frequently within macrophage foam cells, was identified in coronary fibrolipid atheroma (raised lesions, Stary types II through V) in 15 subjects (25%) and early flat lesions in 7 (11%) either by PCR (14, 23%) or ICC (20, 33%). The OR for C pneumoniae in raised atheroma after a level of IgG antibody > or =1:256 >8 years earlier was 6.1 (95% CI, 1.1 to 36.6) and for all coronary tissues after adjustment for multiple potential confounding variables, including tobacco exposure, was 9.4 (95% CI, 2.6 to 33.8). CONCLUSIONS: Serological evidence for C pneumoniae infection frequently precedes both the earliest and more advanced lesions of coronary atherosclerosis that harbor this intracellular pathogen, suggesting a chronic infection and developmental role in coronary heart disease.

Fetal alcohol syndrome in Alaska, 1977 through 1992: an administrative prevalence derived from multiple data sources.

OBJECTIVES: The prevalence and characteristics of fetal alcohol syndrome cases and the usefulness of various data sources in surveillance were examined in Alaska to guide prevention and future surveillance efforts. METHODS: Sixteen data sources in Alaska were used to identify children with fetal alcohol syndrome. Medical charts were reviewed to verify cases, and records were reviewed to provide descriptive data. RESULTS: Fetal alcohol syndrome rates varied markedly by birth year and race, with the highest prevalence (4.1 per 1000 live births) found among Alaska Natives born between 1985 and 1988. Screening and referral programs to diagnostic clinics identified 70% of all recorded cases. The intervention program for children 0 to 3 years of age detected 29% of age-appropriate cases, and Medicaid data identified 11% of all cases; birth certificates detected only 9% of the age-appropriate cases. CONCLUSIONS: Our findings indicate a high prevalence of fetal alcohol syndrome in Alaska and illustrate that reliance on any one data source would lead to underestimates of the extent of fetal alcohol syndrome in a population.

Arterial calcification as a marker for atherosclerosis in three Arctic populations.

Accumulation of calcification in the arterial wall in the course of the atherogenic process is considered to be a manifestation of advanced atherosclerosis. In this study of autopsy specimens from Alaska non-Natives, Alaska Natives, and Greenland Natives, comparisons were made of the prevalence and extent of arterial calcification with that of all raised (advanced) lesions in the thoracic aorta, abdominal aorta, right coronary artery, and left anterior descending coronary artery, to determine the degree to which calcified lesions track the development of advanced lesions. Calcification was determined quantitatively from radiograph images of the fixed specimens; advanced lesion data on these specimens were available from prior studies. Findings show that the prevalence and extent of calcified lesions closely follows the pattern of prevalence and extent of advanced lesions among the groups. We conclude that calcification is a good marker for comparisons of the prevalence and may also provide a good measure of the extent of atherosclerosis in these populations.

A public health perspective on the evaluation of subsistence food safety.

Persistent organic compounds and trace metals are found in the arctic food chain, generating concerns about the safety of subsistence food consumption. One approach for evaluating subsistence food safety is a process used extensively in regulating environmental clean-up and pollution standards. This process, regulatory risk assessment, is substantially different from approaches used in public health risk assessment. Limitations to the use of regulatory risk assessment in assessing public health threats from environmental exposures in the diet include a narrow scope, a lack of incorporation of the nutritional and health benefits of subsistence foods, and the overestimation of risks because of the incorporation of worst-case assumptions in the absence of scientific information. Sound public health policy recognizes that attempts to err on the side of safety for one exposure by recommending reduced consumption of a selected food may inadvertently err on the side of harm by reducing a coexisting exposure of potentially great health benefit. The following discussion should serve as a useful background for future multidisciplinary discussions on the safety of subsistence foods in the Arctic.

Twenty years of trace metal analyses of marine mammals in Alaska: evaluation and summation.

The compilation of existing data on contaminants in the marine food chain is essential in addressing concerns regarding the magnitude of potential human exposures and in the evaluation of subsistence food safety. This paper presents a summary of studies on trace metals in tissues of Alaska marine mammals from the 1970s to the present, along with derived mean tissue trace metal concentrations. The derived mean can serve as a norm against which future monitoring results may be compared, and may be used to estimate human exposure to trace metals through the consumption of marine mammals. Additionally, the variation among studies in the reported mean tissue concentrations has been described through a derived standard deviation. Sufficient analytical and methodological details were available to derive means and standard deviations for tissues in bearded seal, bowhead whale, beluga whale, fur seal, harbor seal, Pacific walrus, and ringed seal. A high concordance between trace metal values reported in tissues (i.e., liver, kidney, muscle) was observed despite significant differences in reported sampling and analytical methodologies. Consistent with other reviews of trace metal concentrations in marine species, the standard deviation of tissue metal concentrations was generally < or = 100% of the reported mean. Significant gaps in available information remain, particularly for muscle tissues and for methylmercury, despite the considerable efforts to monitor marine mammal species in Alaska.

Youth risk behavior survey: the Alaskan perspective.

The Youth Risk Behavior Survey (YRBS) is a national school-based survey used to monitor health risk behaviors that contribute to the leading causes of mortality, morbidity, and social problems among youth and adults in the United States. Both high school and middle school surveys were administered to a representative group of Alaska high school and middle school students for the first time in 1995. Surveys were administered in a confidential and anonymous manner, taking care to assure student privacy. A total of 1,634 high school students and 1,265 middle school students completed surveys. The survey revealed that, for the most part, Alaska students are similar to U.S. students. Among high school students, 23.2% of boys and 15.4% of girls seldom or never used seat belts; 36.4% of boys and 36.5% of girls had smoked cigarettes in the previous 30 days; 23.5% of boys and 6.7% of girls had used smokeless tobacco in the previous 30 days; 48.7% of boys and 48.0% of girls reported having had sexual intercourse at least once; 23.7% of boys and 59.5% of girls were trying to lose weight; and 77.9% of boys and 65.6% of girls had exercised vigorously on three of the previous seven days. The middle school survey was somewhat different than the high school survey, so that results are not directly comparable. Nonetheless, the data indicate that high-risk behaviors, such as tobacco use, drug use, and early sexual intercourse, do occur at the middle school level. The survey also showed that Alaska teens have desirable health behaviors as well, such as frequent exercise and eating fruits and vegetables. The 1995 Alaska YRBS was the first time that representative data on Alaska students were collected on a statewide basis. The YRBS provides Alaska with baseline data that can be compared to national data.

Alcohol-related injury death and alcohol availability in remote Alaska.

CONTEXT: Injury is a major public health problem in Alaska, and alcohol consumption and injury death are associated. OBJECTIVE: To determine the association between injury death, particularly alcohol-related injury death, and alcohol availability in remote Alaska. DESIGN, SETTING, AND PARTICIPANTS: Survey using death certificate data and medical examiner records to compare mortality rates for total injury and alcohol-related injury during 1990 through 1993 among Alaskans aged 15 years and older who had resided in remote villages of fewer than 1000 persons. MAIN OUTCOME MEASURES: Rate ratios of injury death among residents of wet villages (ie, those without a restrictive alcohol law) as compared with injury death among residents of dry villages (ie, those with laws that prohibited the sale and importation of alcohol). RESULTS: Of 302 injury deaths, blood alcohol concentrations (BACs) were available for 200 deaths (66.2%). Of these, 130 (65.0%) had a BAC greater than or equal to 17 mmol/L (> or =80 mg/dL) and were, therefore, classified as alcohol related. The total injury mortality rate was greater among Alaska Natives from wet villages (rate ratio [RR],1.6; 95% confidence interval [CI], 1.3-2.1), whereas this difference was not present for nonnatives (RR, 1.1; 95% CI, 0.3-3.8). For Alaska Natives, the alcohol-related injury mortality rate was greater among residents of wet villages (RR, 2.7; 95% CI, 1.9-3.8) than among residents of dry villages. The strength of this association was greatest for deaths due to motor vehicle injury, homicide, and hypothermia. CONCLUSIONS: Although insufficient data existed to adjust for the effects of all potential confounders, residence in a wet village was associated with alcohol-related injury death among Alaska Native residents of remote Alaska villages. These findings indicate that measures limiting access to alcoholic beverages in this region may decrease alcohol-related injury deaths.

Comparison of atherosclerosis in alaska Natives and nonnatives.

OBJECTIVE: To test the hypothesis that Alaska Natives have fewer atherosclerotic lesions in the coronary arteries and aorta than nonnative Alaska residents. DESIGN: Systematic standardized collection and evaluation of coronary arteries and aortas collected at autopsy. SETTING: Forensic autopsy service in Alaska. SUBJECTS: One hundred thirty Alaska Natives and 115 Alaska nonnatives who underwent forensic autopsy between February 1989 and December 1993. INTERVENTION: None. MAIN OUTCOME MEASURES: Prevalence and extent of atherosclerotic lesions in the aortas and coronary arteries in both populations studied. RESULTS: Alaska Natives had significantly lower prevalence and extent of raised atherosclerotic lesions in the abdominal aorta and coronary arteries than nonnative Alaska residents. CONCLUSIONS: Differences in coronary heart disease mortality between Alaska Natives and nonnatives are, at least in part, the result of fewer atherosclerotic lesions in Alaska Natives.

Exposure to regular gasoline and ethanol oxyfuel during refueling in Alaska.

Although most people are thought to receive their highest acute exposures to gasoline while refueling, relatively little is actually known about personal, nonoccupational exposures to gasoline during refueling activities. This study was designed to measure exposures associated with the use of an oxygenated fuel under cold conditions in Fairbanks, Alaska. We compared concentrations of gasoline components in the blood and in the personal breathing zone (PBZ) of people who pumped regular unleaded gasoline (referred to as regular gasoline) with concentrations in the blood of those who pumped an oxygenated fuel that was 10% ethanol (E-10). A subset of participants in a wintertime engine performance study provided blood samples before and after pumping gasoline (30 using regular gasoline and 30 using E-10). The biological and environmental samples were analyzed for selected aromatic volatile organic compounds (VOCs) found in gasoline (benzene, ethylbenzene, toluene, m-/p-xylene, and o-xylene); the biological samples were also analyzed for three chemicals not found in gasoline (1,4-dichlorobenzene, chloroform, and styrene). People in our study had significantly higher levels of gasoline components in their blood after pumping gasoline than they had before pumping gasoline. The changes in VOC levels in blood were similar whether the individuals pumped regular gasoline or the E-10 blend. The analysis of PBZ samples indicated that there were also measurable levels of gasoline components in the air during refueling. The VOC levels in PBZ air were similar for the two groups. In this study, we demonstrate that people are briefly exposed to low (ppm and sub-ppm) levels of known carcinogens and other potentially toxic compounds while pumping gasoline, regardless of the type of gasoline used.

Outbreak of viral gastroenteritis due to a contaminated well. International consequences.

CONTEXT: Small round-structured viruses (SRSVs) are known to cause viral gastroenteritis, but until now have not been confirmed in the implicated vehicle in outbreaks. OBJECTIVE: Investigation of a gastroenteritis outbreak. DESIGN: After applying epidemiologic methods to locate the outbreak source, we conducted environmental and laboratory investigations to elucidate the cause. SETTING: Tourists traveling by bus through Alaska and the Yukon Territory of Canada. PARTICIPANTS: Staff of a restaurant at a business complex implicated as the outbreak source, convenience sample of persons on buses that had stopped there, and bus employees. MAIN OUTCOME MEASURES: Odds ratios (ORs) for illness associated with exposures. Water samples from the restaurant and stool specimens from tourists and restaurant staff were examined by nucleic acid amplification using reverse transcription polymerase chain reaction and sequencing of viral amplification products. RESULTS: The itineraries of groups of tourists manifesting vomiting or diarrhea were traced back to a restaurant where buses had stopped 33 to 36 hours previously. Water consumption was associated with illness (OR, 5.3; 95% confidence interval [CI], 2.3-12.6). Eighteen of 26 employees of the business complex were ill; although not the index case, an employee ill shortly before the outbreak lived in a building connected to a septic pit, which was found to contaminate the well supplying the restaurant's water. Genotype 2/P2B SRSV was identified in stool specimens of 2 tourists and 1 restaurant employee. Stools and water samples yielded identical amplification product sequences. CONCLUSIONS: The investigation documented SRSVs in a vehicle epidemiologically linked to a gastroenteritis outbreak. The findings demonstrate the power of molecular detection and identification and underscore the importance of fundamental public health practices such as restaurant inspection, assurance of a safe water supply, and disease surveillance.

Statewide assessment of lead poisoning and exposure risk among children receiving Medicaid services in Alaska.

OBJECTIVE: Lead poisoning is a well-recognized public health concern for children living in the United States. In 1992, Health Care Financing Administration (HCFA) regulations required lead poisoning risk assessment and blood lead testing for all Medicaid-enrolled children ages 6 months to 6 years. This study estimated the prevalence of blood lead levels (BLLs) >/=10 microg/dL (>/=0.48 micromol/L) and the performance of risk assessment questions among children receiving Medicaid services in Alaska. DESIGN: Measurement of venous BLLs in a statewide sample of children and risk assessment using a questionnaire modified from HCFA sample questions. SETTING: Eight urban areas and 25 rural villages throughout Alaska. PATIENTS: Nine hundred sixty-seven children enrolled in Medicaid, representing a 6% sample of 6-month- to 6-year-old Alaska children enrolled in Medicaid. OUTCOME MEASURE(S): Determination of BLL and responses to verbal-risk assessment questions. RESULTS: BLLs ranged from <1 microg/dL (<0.048 micromol/L) to 21 microg/dL (1.01 micromol/L) (median, 2.0 microg/dL or 0.096 micromol/L). The geometric mean BLLs for rural and urban children were 2.2 microg/dL (0.106 micromol/L) and 1.5 microg/dL (0.072 micromol/L), respectively. Six (0.6%) children had a BLL >/=10 microg/dL; only one child had a BLL >/=10 microg/dL (11 microg/dL or 0.53 micromol/L) on retesting. Children whose parents responded positively to at least one risk factor question were more likely to have a BLL >/=10 microg/dL (prevalence ratio = 3.1; 95% confidence interval = 0.4 to 26.6); the predictive value of a positive response was <1%. CONCLUSIONS: In this population, the prevalence of lead exposure was very low (0.6%); only one child tested (0.1%) maintained a BLL >/=10 microg/dL on confirmatory testing; no children were identified who needed individual medical or environmental management for lead exposure. Universal lead screening for Medicaid-enrolled children is not an effective use of public health resources in Alaska. Our findings identify an example of the importance in considering local and regional differences when formulating screening recommendations and regulations, and continually reevaluating the usefulness of federal regulations.

Blood benzene concentrations in workers exposed to oxygenated fuel in Fairbanks, Alaska.

OBJECTIVE: In November 1992 residents of Fairbanks, Alaska became concerned about the potential health effects of an oxygenated fuel program during which 15% (by volume) methyl tertiary butyl ether (MTBE) was added to gasoline. To address those concerns, we earlier completed a survey of occupational exposure to MTBE. We conducted a follow-up survey of workers' exposure to benzene from gasoline in Fairbanks. DESIGN: Cross-sectional exposure survey. METHODS: We examined blood concentrations of benzene from a convenience sample of workers taken in December 1992 during the oxygenated fuel program and from another convenience sample of workers taken in February 1993 after the program was suspended. RESULTS: In December, the median blood benzene concentration of samples taken from four mechanics after their workshift (postshift) was 1.32 micrograms/l (range, 0.84-2.61 micrograms/l), and seven nonmechanics (drivers and other garage workers) had a median postshift blood benzene concentration of 0.27 microgram/l (range, 0.09-0.45 microgram/l). In February, nine mechanics had a median postshift blood benzene concentration of 1.99 micrograms/l (range, 0.92-3.23 micrograms/l), and nine nonmechanics had a median postshift blood benzene concentration of 0.26 microgram/l (range, 0.2-0.46 microgram/l). CONCLUSION: Mechanics had higher blood benzene concentrations than did nonmechanics, but further study is needed to determine the impact of the oxygenated fuel program on exposure to benzene.