Investigating childhood leukemia in Churchill County, Nevada

BACKGROUND

Sixteen children diagnosed with acute leukemia between 1997 and 2002 lived in Churchill County, Nevada, at the time of or before their illness. Considering the county population and statewide cancer rate, fewer than two cases would be expected.

OBJECTIVES

In March 2001, the Centers for Disease Control and Prevention led federal, state, and local agencies in a cross-sectional, case-comparison study to determine if ongoing environmental exposures posed a health risk to residents and to compare levels of contaminants in environmental and biologic samples collected from participating families.

METHODS

Surveys with more than 500 variables were administered to 205 people in 69 families. Blood, urine, and cheek cell samples were collected and analyzed for 139 chemicals, eight viral markers, and several genetic polymorphisms. Air, water, soil, and dust samples were collected from almost 80 homes to measure more than 200 chemicals.

RESULTS

The scope of this cancer cluster investigation exceeded any previous study of pediatric leukemia. Nonetheless, no exposure consistent with leukemia risk was identified. Overall, tungsten and arsenic levels in urine and water samples were significantly higher than national comparison values; however, levels were similar among case and comparison groups.

CONCLUSIONS

Although the cases in this cancer cluster may in fact have a common etiology, their small number and the length of time between diagnosis and our exposure assessment lessen the ability to find an association between leukemia and environmental exposures. Given the limitations of individual cancer cluster investigations, it may prove more efficient to pool laboratory and questionnaire data from similar leukemia clusters.

Nursing home outbreak of invasive group a streptococcal infections caused by 2 distinct strains

OBJECTIVE

To identify factors contributing to a cluster of deaths from invasive group A streptococcus (GAS) infection in a nursing home facility and to prevent additional cases.

DESIGN

Outbreak investigation.

SETTING

A 146-bed nursing home facility in northern Nevada.

METHODS

We defined a case as the isolation of GAS from a normally sterile site in a resident of nursing home A. To identify case patients, we reviewed resident records from nursing home A, the local hospital, and the hospital laboratory. We obtained oropharyngeal and skin lesion swabs from staff and residents to assess GAS colonization and performed emm typing on available isolates. To identify potential risk factors for transmission, we performed a cohort study and investigated concurrent illness among residents and surveyed staff regarding infection control practices.

RESULTS

Six residents met the case patient definition; 3 (50%) of them died. Among invasive GAS isolates available for analysis, 2 distinct strains were identified: emm11 (3 isolates) and emm89 (2 isolates). The rate of GAS carriage was 6% among residents and 4% among staff; carriage isolates were emm89 (8 isolates), emm11 (2 isolates), and emm1 (1 isolate). Concurrently, 35 (24%) of the residents developed a respiratory illness of unknown etiology; 41% of these persons died. Twenty-one (30%) of the surveyed employees did not always wash their hands before patient contacts, and 27 (38%) did not always wash their hands between patient contacts.

CONCLUSIONS

Concurrent respiratory illness likely contributed to an outbreak of invasive GAS infection from 2 strains in a highly susceptible population. This outbreak highlights the importance of appropriate infection control measures, including respiratory hygiene practices, in nursing home facilities.

Nevada's academic-practice collaboration: public health preparedness possibilities outside an academic center

The Nevada State Health Division developed a local academic-practice partnership with the University of Nevada Reno's Master of Public Health Program to assess the bioterrorism risk communication, information, response, and training needs of professional and public stakeholder groups throughout Nevada. Between October 16, 2002, and April 13, 2004, 22 needs assessment focus groups and 125 key informant interviews were conducted to gather information on the diverse needs of the stakeholders. The themes that emerged from these activities included the need for effective pre-event education and training; a coordinated and responsive public health preparedness infrastructure; honest, accurate, and timely communication in the event of a bioterrorism situation; and appropriate information dissemination methods and technology. The data collected through this needs assessment gave the Nevada State Health Division vital information to plan public health preparedness initiatives. The establishment of local academic-practice partnerships for states without a Centers for Disease Control and Prevention-funded Academic Center for Public Health Preparedness is an effective way for health departments to develop their public health preparedness infrastructure while simultaneously training the future public health workforce.

Probability estimates for the unique childhood leukemia cluster in Fallon, Nevada, and risks near other U.S. Military aviation facilities

A unique cluster of childhood leukemia has recently occurred around the city of Fallon in Churchill County, Nevada. From 1999 to 2001, 11 cases were diagnosed in this county of 23,982 people. Exposures related to a nearby naval air station such as jet fuel or an infectious agent carried by naval aviators have been hypothesized as potential causes. The possibility that the cluster could be attributed to chance was also considered. We used data from the Surveillance, Epidemiology, and End Results Program (SEER) to examine the likelihood that chance could explain this cluster. We also used SEER and California Cancer Registry data to evaluate rates of childhood leukemia in other U.S. counties with military aviation facilities. The age-standardized rate ratio (RR) in Churchill County was 12.0 [95% confidence interval (CI), 6.0-21.4; p = 4.3 times symbol 10(-9)]. A cluster of this magnitude would be expected to occur in the United States by chance about once every 22,000 years. The age-standardized RR for the five cases diagnosed after the cluster was first reported was 11.2 (95% CI, 3.6-26.3). In contrast, the incidence rate was not increased in all other U.S. counties with military aviation bases (RR = 1.04; 95% CI, 0.97-1.12) or in the subset of rural counties with military aviation bases (RR = 0.72; 95% CI, 0.48-1.08). These findings suggest that the Churchill County cluster was unlikely due to chance, but no general increase in childhood leukemia was found in other U.S. counties with military aviation bases.

Acute Sin Nombre hantavirus infection without pulmonary syndrome, United States

Hantavirus pulmonary syndrome (HPS) occurs in most infections with Sin Nombre virus and other North American hantaviruses. We report five cases of acute hantavirus infection that did not fit the HPS case definition. The patients had characteristic prodromal symptoms without severe pulmonary involvement. These cases suggest that surveillance for HPS may need to be expanded.

Effects of Fat Content on the Microstructure of Domiati-Type Cheese

Domiati-type cheese was manufactured from skim milk and milk fortified to contain 6.1% milkfat. At the time of hooping and at 8 weeks of ripening in brine, samples were removed and prepared for scanning electron microscopy. Photomicrographs revealed differences in the internal and external microstructure of the two types of cheese, which became more evident during ripening. The microstructure of the high-fat cheese exhibited the greatest morphological alterations. Addition of a mixed culture to the vat milk did not appear to give rise to any additional changes in microstructure although the presence of microbial cells was readily evident and a more intense flavor developed in the finished cheese.

Nitrate Losses from Disturbed Ecosystems

A systematic examination of nitrogen cycling in disturbed forest ecosystems demonstrates that eight processes, operating at three stages in the nitrogen cycle, could delay or prevent solution losses of nitrate from disturbed forests. An experimental and comparative study of nitrate losses from trenched plots in 19 forest sites throughout the United States suggests that four of these processes (nitrogen uptake by regrowing vegetation, nitrogen immobilization, lags in nitrification, and a lack of water for nitrate transport) are the most important in practice. The net effect of all of these processes except uptake by regrowing vegetation is insufficient to prevent or delay losses from relatively fertile sites, and hence such sites have the potential for very high nitrate losses following disturbance.

Scanning electron microscopy of microbial cells on membrane filters

Scanning electron micrographs of a Pseudomonas species, Staphylococcus aureus, and Bacillus subtilis on two membrane filtration systems are compared.

Flavin-linked dehydrogenation of ether glycols by cell-free extracts of a soil bacterium

Payne, W. J. (University of Georgia, Athens), and R. L. Todd. Flavin-linked dehydrogenation of ether glycols by cell-free extracts of a soil bacterium. J. Bacteriol. 91:1533-1536. 1966.-Cell-free extracts of bacterium TEG-5 grown on tetraethylene glycol dehydrogenated a variety of ether glycols and nonylphenoxy and secondary alcohol ethoxy derivatives. Nicotinamide nucleotides did not serve as electron acceptors, but ferricyanide was effective. Dialysis of crude extract depressed activity with tetraethylene glycol, which was restored then by flavine adenine dinucleotide (FAD) or boiled extract supernatant fluid (BES) but not by other flavins. Precipitatation of extract protein at pH 4.0 at 80% ammonium sulfate saturation dissociated FAD and yielded an inactive fraction. Activity was restorable by FAD and BES but not by other flavins. Ethylene glycol was not dehydrogenated by the acid ammonium sulfate fraction with FAD. Atabrine inhibited tetraethylene glycol oxidation, and the inhibition was relieved by FAD but not by other flavins. Tergitols which have sulfated ethoxy side chains on secondary alcohols were not dehydrogenated, but those with free ethoxy side chains on identical alcohols were.