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Context: Although the cost-effectiveness and cost-benefit of influenza vaccination are well established for persons aged 65 years or older, the benefits for healthy adults younger than 65 years are less clear.Objective: To evaluate the effectiveness and cost-benefit of influenza vaccine in preventing influenza-like illness (ILI) and reducing societal costs of ILI among healthy working adults.Design: Double-blind, randomized, placebo-controlled trial conducted during 2 influenza seasons.Setting and Participants: Healthy adults aged 18 to 64 years and employed full-time by a US manufacturing company (for 1997-1998 season, n = 1184; for 1998-1999 season, n = 1191).Interventions: For each season, participants were randomly assigned to receive either trivalent inactivated influenza vaccine (n = 595 in 1997-1998 and n = 587 in 1998-1999) or sterile saline injection (placebo; n = 589 in 1997-1998 and n = 604 in 1998-1999). Participants in 1997-1998 were rerandomized if they participated in 1998-1999.Main Outcome Measures: Influenza-like illnesses and associated physician visits and work absenteeism reported in biweekly questionnaires by all participants, and serologically confirmed influenza illness among 23% of participants in each year (n = 275 in 1997-1998; n = 278 in 1998-1999); societal cost of ILI per vaccinated vs unvaccinated person.Results: For 1997-1998 and 1998-1999, respectively, 95% (1130/1184) and 99% (1178/1191) of participants had complete follow-up, and 23% in each year had serologic testing. In 1997-1998, when the vaccine virus differed from the predominant circulating viruses, vaccine efficacy against serologically confirmed influenza illness was 50% (P =.33). In this season, vaccination did not reduce ILI, physician visits, or lost workdays; the net societal cost was $65.59 per person compared with no vaccination. In 1998-1999, the vaccine and predominant circulating viruses were well matched. Vaccine efficacy was 86% (P =.001), and vaccination reduced ILI, physician visits, and lost workdays by 34%, 42%, and 32%, respectively. However, vaccination resulted in a net societal cost of $11.17 per person compared with no vaccination.Conclusion: Influenza vaccination of healthy working adults younger than 65 years can reduce the rates of ILI, lost workdays, and physician visits during years when the vaccine and circulating viruses are similar, but vaccination may not provide overall economic benefits in most years. JAMA. 2000;284:1655-1663. [ABSTRACT FROM AUTHOR]

We study centre symmetry sets and equidistants for a I-parameter family of plane curves where, for a special member of the family, there exist two inflexions with parallel tangents. Some results can be obtained by reducing a generating family to normal forms, but others require direct calculation from the generating family.

This study was undertaken to determine the impact of exposure to metal removal fluids (MRFs) on the respiratory health of exposed workers. The outcome measure selected was the rate of hospital admissions for nonmalignant respiratory disease episodes as determined from healthcare insurance claims data. A cohort of MRF-exposed employees was assembled from 11 manufacturing facilities where MRFs were extensively used in the manufacture of automotive engines, transmissions, and other machined parts. The MRF-exposed cohort included 20,434 employees of such facilities who worked at any time from 1993 through 1997. A non-MRF-exposed cohort was assembled from other employees of the same company during the same time period, but working in warehouse operations and other manufacturing facilities that did not use MRFs or any known respiratory sensitizing agents. The non-exposed cohort included 8681 employees. The crude hospital admission rate for the MRF-exposed cohort was 44 percent higher than that of the non-exposed cohort over the 5-year study period (6.67 vs. 4.62 per 1000 person years at risk, p < 0.05). With age adjustment, the MRF population's rate was still 35 percent higher, and still statistically significant. A nested case-control study was also conducted to determine whether the risk of hospital admission increased with the level of MRF exposure in the population working in MRF plants. The industrial hygiene reconstruction found the levels of exposures of both cases and controls to be very low, with the vast majority of study subjects (more than 90%) having exposures of less than 0.5 mg/m(3). The case-control study did not find any association between increased levels of MRF exposure and risk of hospitalization. The study did document an elevated risk of hospitalization among a sizable population employed in manufacturing operations where MRFs are used.

This paper reviews surveillance approaches for occupational injuries and evaluates three emerging methodologies for the enhancement of work-related injury surveillance: (1) narrative data analysis, (2) data set linkage, and (3) comprehensive company-wide surveillance systems. All three methods are the result of new applications of computer hardware and software that have apparent strengths and limitations. A major strength is the improved description of work exposures and related injuries leading to better understanding of injury etiology. This understanding, however, is limited by the data quality and completeness entered on records at the time of the injury. We recommend (1) more widespread inclusion of narrative text in databases, analyses of which can be a valuable supplement to injury coded data; (2) the increased use of data set linkage studies to combine injury and work-history data; and (3) the development of comprehensive company-wide surveillance systems to expedite the use of epidemiologic data for occupational injury prevention activities. Further development of these methods and others is encouraged, especially in light of technological advancements in data capture, analysis and presentation. Only through such efforts can we best apply epidemiologic principles to preventing injuries in the workplace.

A large diarrhea outbreak due to enteroinvasive Escherichia coli (EIEC) serogroup O143 occurring in Houston, Tex., provided the opportunity to investigate aspects of the molecular epidemiology of this and related organisms. This was done by comparing the plasmid patterns and the chromosomal restriction endonuclease digestion patterns by pulsed-field gel electrophoresis (PFGE) of EIEC from the outbreak, other E. coli from the same serogoup (O143), and EIEC isolated from other patients with diarrhea. Among the isolates studied, there was marked restriction fragment length polymorphism. All 3 non-O143 EIEC isolates had very different restriction endonuclease digestion patterns, as did 5 of 5 O143 non-EIEC isolates and 6 of 15 O143 EIEC isolates. Four Houston outbreak O143 EIEC isolates had the same restriction pattern as an O143 EIEC strain isolated 2 months before in Mexico and was nearly identical to another two O143 EIEC Mexican isolates. These related strains also had the same plasmid pattern; however, the presence of only a few plasmid bands, versus the 21 to 30 chromosomal bands seen with PFGE, suggests that plasmid patterns could be a less specific way to distinguish different strains. These results demonstrate that PFGE can distinguish between different E. coli strains of the same serogroup and phenotype. This technique can also identify relatedness within O143 EIEC, and our data suggest the spread of a strain of EIEC from Mexico to Houston, where it caused a large outbreak. PFGE may be useful to study the epidemiology of EIEC.

Using a modification of the traditional cohort mortality methodology, risk estimates of death due to brain tumors were calculated for production and nonproduction employees of Dow Chemical U.S.A., Texas Division. A total of 25 malignant, benign and unspecified brain tumors were identified using a geographically limited record-linkage process. Expected deaths were extrapolated from 1,666 white males in a 5% sample of the 1940 through 1977 total workforce. The resulting sample-based standardized mortality ratios (which were not evaluated for statistical significance) suggest, at most, only a slight increased risk of mortality from brain tumors for the overall time period. There was, however, a probable elevated risk associated with first employment prior to 1945. To date, diminished risk has been noted for those hired during subsequent years.

An outbreak of St. Louis encephalitis (SLE) resulted in 28 cases of the disease in Harris County, Texas, in 1986. The cases occurred principally in Baytown, in eastern Harris County, but five cases were also recognized in Houston. The risk of illness increased sharply with age, and all five fatal cases were in persons greater than 55 y. Case-control methods were used for the first time to study factors associated with the risk of acquiring SLE. Risk was associated with residences poorly sealed against mosquitoes (non-air-conditioned residences and those with inadequate screens). The number of hours spent outdoors and in outdoor activities, except sitting immediately outside residences, were not associated with risk. Our observations suggest that exposure to vector mosquitoes may have occurred indoors. No host factors were significantly associated with risk of acquiring SLE, but more cases were cigarette smokers and had family histories of hypertension or cerebrovascular disease.

A retrospective cohort mortality study of phosphate fertilizer production workers was undertaken to determine whether this group is at increased risk of dying from any cause, particularly from lung cancer. A total of 3,199 workers who had ever been employed at one facility were included in this investigation. These workers were followed for vital status ascertainment from their first date of employment up to December 1, 1977, or the date of death, whichever occurred first. Overall, no statistically significant elevations in cause-specific mortality were observed for the entire study population. However, when the analysis was stratified by duration of employment, and length of follow-up, a statistically significant (P less than .05) excess in lung cancer mortality was observed among workers with more than 10 yr of employment and follow-up (standardized mortality ratio = 411). Because of the small number of deaths involved, and because we had prior knowledge of a lung cancer cluster at this plant, we believe that these findings should be viewed as suggestive, and that other investigations in plants with similar exposures are needed to clarify whether an occupationally related lung cancer excess truly exists.

During the six-month period since this investigation was initiated, an increased risk of death due to brain tumor was linked with employment at the Texas Division of Dow Chemical by the results of a case-control study based on county death certificates. Specifically, the county-based case-control study yielded an odds ratio of 2.54 with a 90% confidence interval of the odds ratio extending from 1.23 to 6.80. Additional investigations were initiated which resulted in the ascertainment of 25 brain tumor deaths among former Dow employees. Of these cases, 84% were initially employed between 1940 and 1946 and 64% can be described as glioblastomas or astrocytomas grade III and IV. Detailed protocols have been developed for a sample-based cohort study and a series of in-plant case-control studies. The sample-based cohort study is nearing completion and the in-plant case-control studies are anticipated to begin in the near future. The study design serving as the framework of this investigation represents a modest departure from the traditional epidemiologic study designs. This sample-based approach was designed to circumvent or minimize the usual problems associated with the use of massive collections of data that have been partially automated, if at all. The anticipated benefits will be conservation of limited staff resources and a reduction of the time necessary to complete a large-scale epidemiologic investigation.

A general mortality survey was done on a 5% random-start systematic sample (N = 1,666) of present and former white male employees of a Texas chemical plant. The purpose was to determine whether there were any unusual patterns of cause-specific mortality that would require further research with case-control studies. Mortality risks were examined by duration of employment and year of hire as surrogates for more specific exposure data. Among all employees in the sample, there was significant excess mortality due to All Cancer, Ill-Defined Conditions, and All External Causes of Death, and a significant deficit from All Circulatory Diseases. The excess mortality from All Cancer was primarily attributable to excess cancers of the kidney, lung, and pancreas. The excesses for lung and kidney cancer were statistically significant. Those employed for 1 year or more experienced significantly lower mortality from All Causes than those employed for less than 1 year.

Cryptosporidiosis has typically been considered a disease of animals, and the occasional human case has been considered a rare zoonosis or evidence of immunoincompetence. In this report, person-to-person transmission is postulated for illness documented in two of five rooms of a day-care center. Of 46 persons (34 children and 12 staff members), 29 (63%) became ill, and 27 (58.7%) had Cryptosporidium in their stools. Symptoms in children included diarrhea (55%), weight loss (25%), flatulence (15%), and fever (10%). Symptoms of cryptosporidiosis ceased without treatment, and three months later all previously infested children had negative stool specimens. Questionnaires administered to parents revealed no association with water, travel, or ill pets. Cultures for Salmonella, Shigella, and Campylobacter were negative; no viral cultures were done. All affected children and their parents were immunocompetent. It is presumed that this outbreak occurred as a result of person-to-person transmission of the protozoa in the day-care centers, primarily by staff with inadequate hygiene practices. Physicians should look for this organism in children or adults who present with diarrhea and gastroenteritis in which the pathogenic agent is not readily identifiable by the usual bacterial cultures.