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PubMed1984

[Cartographic method in the epidemiological study of infections and infestations. III. The study of patterns of tetanus spread in relation to edaphic factors].

The conjugate analysis of the address map, the density chart and the map of the density field of tetanus morbidity with the soil map has revealed that this morbidity is linked with the properties of the soil. The map of the density field has proved to be most suitable for such analysis. Morbidity is unevenly distributed over the territory. Its highest level is observed in regions with neutral or almost neutral soils. Regions with soils having acidic or alkaline properties are characterized by low morbidity levels. The dependence of morbidity levels on the proportional distribution of soils with different properties has been determined. These data may be used for the prognosis of morbidity on territories with soils differing in their acidic and alkaline properties.

Disease Reservoirs↗
PubMed1998

Molecular methods for epidemiological and diagnostic studies of fungal infections.

Over the past two decades there has been a remarkable increase in the incidence of invasive fungal infections. Molecular methods, such as karyotyping, restriction analysis and polymerase chain reaction (PCR), have now been applied to improve our current understanding of the epidemiology of these fungal infections. For example, investigations on nosocomial outbreaks of fungal infections have been greatly facilitated by molecular methods. In addition, the ability to diagnose and identify deep-seated mycoses may be enhanced by the use of molecular techniques. In the near future it is possible that PCR-based methods will supplement, or perhaps even replace, traditional methods for detection of Candida albicans blood stream infections, invasive aspergillosis and Pneumocystis carinii pneumonia. This review examines the progress of molecular biology into the clinical arena of fungal epidemiology, laboratory identification and diagnosis.

DNA, Fungal↗
PubMed1984

Dietary history methods for epidemiologic studies: application in a case-control study of vitamin A and lung cancer.

A dietary history method for use in a case-control study of vitamin A and lung cancer is described. The method was designed to obtain estimates of the usual frequencies and quantities of 84 major food sources of vitamin A and carotene consumed prior to symptoms of disease in cases and during the same time period in matched controls. Amounts were estimated from photographs of each item that showed three different quantities. The development of the questionnaire is described in detail, as well as the data collection and analysis. The results of the study showed that relative to those men with the highest intakes, the men who consumed less vitamin A or carotene had a higher risk for lung cancer in a general dose-response fashion. These findings were not apparent for females. Recommendations regarding dietary methodology for future studies concerning vitamin A and carotene intakes include further research on the validation and reproducibility of the dietary methods, identification of appropriate biological markers that reflect past exposures of vitamin A and carotene, and further research on the vitamin A and carotene content of available food items.

Carotenoids↗
PubMed2005

Phene Plate (PhP) biochemical fingerprinting. A screening method for epidemiological typing of enterococcal isolates.

Pulsed-field gel electrophoresis (PFGE) is currently considered the gold standard for genotyping of enterococci. However, PFGE is both expensive and time-consuming. The purpose of this study was to investigate whether the PhP system can be used as a reliable clinical screening method for detection of genetically related isolates of enterococci. If so, it should be possible to minimize the number of isolates subjected to PFGE typing, which would save time and money. Ninety-nine clinical enterococcal isolates were analysed by PhP (similarity levels 0.90-0.975) and PFGE (similarity levels < or =3 and < or =6 bands) and all possible pairs of isolates were cross-classified as matched or mismatched. We found that the probability that a pair of isolates (A and B) belonging to the same type according to PhP also belong to the same cluster according to PFGE, i.e. p(A(PFGE)=B(PFGE) * A(PhP)=B(PhP)), and the probability that a pair of isolates of different types according to PhP also belong to different clusters according to PFGE, i.e. p(A(PFGE) not equalB(PFGE) * A(PhP) not equalB(PhP)), was relatively high for E. faecalis (0.86 and 0.96, respectively), but was lower for E. faecium (0.51 and 0.77, respectively). The concordance which shows the probability that PhP and PFGE agree on match or mismatch was 86%-93% for E. faecalis and 54%-66% for E. faecium, which indicates that the PhP method may be useful for epidemiological typing of E. faecalis in the current settings but not for E. faecium.

Bacterial Typing Techniques↗
PubMed2000

Anonymous statistical methods versus cryptographic methods in epidemiology.

Sensitive data are most often indirectly identifiable and so need to be rendered anonymous in order to ensure privacy. Statistical methods to provide anonymity require data perturbation and so generate data processing difficulties. Encryption methods, while preserving confidentiality, do not require data modification.

Computer Security↗
PubMed1999

Statistical methods in epidemiology. III. The odds ratio as an approximation to the relative risk.

PURPOSE: This paper introduces readers to case-control studies and how to analyse them. Specifically, the odds ratio statistic is discussed. The importance of the odds ratio in epidemiology is that it is used as an approximation to the true relative risk. METHOD: Data are presented in the form of 2 x 2 contingency tables, and a method for calculating the odds ratio is presented. An extension to 2 x k tables (where k > 2) is given, as is a graphical method for plotting odds ratios. Confidence intervals based on the Normal approximation are introduced. RESULTS: Some properties of the odds ratio statistic are illustrated by taking examples from the author's own teaching experiences. CONCLUSION: As long as the odds ratio is not used uncritically as an estimate of the relative risk, it remains an attractive statistic for epidemiologists to calculate.

Confidence Intervals↗
PubMed1983

[Etiologic study of chronic nonspecific bronchopneumopathies in the work environment].

Epidemiological methods may be used to study the causes of respiratory troubles at work, to test the hypothesis that there is a statistically significant relationship between professional risk factors and respiratory disease. The prognostic value of certain indices and the impact of preventative measures may also be assessed. The choice of method, type of enquiry and selection of the population to be studied and the resources to be used depend on the aims of the study. The definitions both of occupational exposure and the disease should be clearly established in the protocol. The questionnaire, which is indispensable in all investigation into respiratory disorder, should be adapted to the specific research project (for contents, lay-out, relevance and order of questions, allowing for distorting factors). The final objective in the application of an epidemiological method to study occupational risk factors is to develop a preventative strategy at each stage, but most importantly at the very first stage to prevent the appearance of respiratory troubles.

Air Pollutants, Occupational↗
PubMed2000

Anonymous statistical methods versus cryptographic methods in epidemiology.

Sensitive data are most often indirectly identifiable and so need to be rendered anonymous in order to ensure privacy. Statistical methods to provide anonymity require data perturbation and so generate data processing difficulties. Encryption methods, while preserving confidentiality, do not require data modification.

Journal Article↗
PubMed1995

Polymicrobial gram-negative bacteremia associated with saline solution flush used with a needleless intravenous system.

BACKGROUND: During a 2-week period, seven cases of nosocomial polymicrobial gram-negative rod bacteremia occurred on a 39-bed medical and cardiac step-down unit. Combinations of Enterobacter cloacae (seven isolates), Klebsiella pneumoniae (five isolates), and Citrobacter freundii (two isolates) were isolated from blood cultures. METHODS: Concurrent and retrospective chart reviews were used to look for further cases and common exposures. Epidemiologic methods were used to refine determination of common exposure. Restriction enzyme DNA analysis was performed on the isolates. RESULTS: Concurrent and retrospective chart reviews revealed four additional possible cases during the same period. All case patients were exposed, through peripheral saline solution locks or central venous catheters, to saline solution "flush" from a central 0.9% saline solution bag and a needleless dispensing pin. Epidemiologic methods implicated probable extrinsic contamination of a single bag and pin used during a 24-48-hour period (Fisher's Exact Test, p < 0.002). There were no other common exposures. Restriction enzyme DNA analysis of the isolates further supported a common source for the outbreak. CONCLUSIONS: The introduction of needleless intravascular systems has been embraced for employee protection. Our report is the first to raise the question of patient safety with such systems. This outbreak highlights the inherent risks in rapid introduction of new technologies and points out the delicate balance among patient health, employee safety, and cost containment.

Bacteremia↗
PubMed2006

Double-locus sequence typing using clfB and spa, a fast and simple method for epidemiological typing of methicillin-resistant Staphylococcus aureus.

Sequence-based epidemiological typing of methicillin-resistant Staphylococcus aureus (MRSA) has recently been promoted because it results in unambiguous data sets that can be organized in local and global databases. The replacement of previous typing methods, such as the highly discriminatory pulsed-field gel electrophoresis (PFGE), has been attempted with various markers and typing schemes, including spa typing and multilocus sequence typing. However, despite a number of advantages, none of these methods showed convincing evidence for performance in epidemiological typing comparable to that of PFGE. By using three sets of 48 MRSA strains comprising isolates that were (i) genetically highly diverse, (ii) genetically related, and (iii) obtained from long-term carriers, we analyzed the performance of the four highly polymorphic S. aureus markers: clfA, clfB, fnbA, and spa. Typeability, discriminatory power, in vivo stability, and evolution of these markers were compared to those of PFGE. Clearly, none of the markers alone could match the discriminatory power of PFGE (63 genotypes; index of discrimination of 0.96). Instead, this could be achieved by combining markers in pairs. We showed that by using only 3' partial sequences of approximately 500 bp, the majority of each marker's discriminatory power was displayed, and using the partial sequences, the best performance was obtained with the combination of clfB and spa (57 genotypes; index of discrimination of 0.94). Genetic changes were not observed for any of the sequence markers over a period of 3 years and in the case of partial sequences for a period of more than 4 years. This is in contrast to PFGE where changes occurred after several months. The genetic differences found between isolate pairs of long-term carriers and among highly related isolates indicated clonal evolution. A typing scheme based on 500-bp 3' partial sequences of clfB and spa is proposed.

Adhesins, Bacterial↗
PubMed2005

Statistical methods in epidemiology. VIII. On the use of likelihood ratios for diagnostic testing with an application to general practice.

PURPOSE: An array of statistical methods is available for 2 x 2 contingency table analysis. These include odds ratios, reliability coefficients and the Chi-squared test. This paper continues the '2 x 2' theme but extends it to look at diagnostic testing. The setting is primary care, the disease is urological cancer. METHOD: Several statistical indices are discussed to measure diagnostic efficiency; these include sensitivity, specificity and the likelihood ratio. The latter can be converted into a flexible 'weight of evidence', which is equivalent to the naive Bayes' discriminant. RESULTS: The utility of the naive Bayes' discriminant is illustrated in a primary care setting. CONCLUSION: The naive Bayes' discriminant has proved to be the most durable of statistical discriminants in medical diagnosis. The reason for its durability is ease of use. Despite a concern about independence, it remains a popular choice as a diagnostic aid.

Aged↗
PubMed2006

Estimation of European wild boar relative abundance and aggregation: a novel method in epidemiological risk assessment.

Wild boars are important disease reservoirs. It is well known that abundance estimates are needed in wildlife epidemiology, but the expense and effort required to obtain them is prohibitive. We evaluated a simple method based on the frequency of faecal droppings found on transects (FBII), and developed a spatial aggregation index, based on the runs test statistic. Estimates were compared with hunting data, and with porcine circovirus and Aujeszky's disease virus seroprevalences and Mycobacterium tuberculosis complex and Metastrongylus spp. prevalence. The FBII and the aggregation index were correlated with the hunting index, but both of the former estimates correlated better than the latter with the disease prevalences. Hence, at least in habitats with high wild boar densities, the FBII combined with the aggregation index constitutes a cheap and reliable alternative for wild boar abundance estimation that can be used for epidemiological risk assessment, even outside the hunting season and in areas with no available data on hunting activities.

Animals↗