Epidemiological Techniques Research Articles

The impact of globalisation on the distribution of Echinococcus multilocularis

In the past three decades, Echinococcus multilocularis, the cause of human alveolar echinococcosis, has been reported in several new countries both in definitive hosts (canids) as well as in people. Unless treated, infection with this cestode in people is fatal. In previously endemic countries throughout the Northern Hemisphere, geographic ranges and human and animal prevalence levels seem to be increasing. Anthropogenic influences, including increased globalisation of animals and animal products, and altered human/animal interfaces are thought to play a vital role in the global emergence of this pathogenic cestode. Molecular epidemiological techniques are a useful tool for detecting and tracing introductions, and differentiating these from range expansions.

Heat‐processed Carcinogens: What Can We Learn from the “Coffee ‐ Cancer Paradox”?

Trace level animal carcinogens in heated foods, including acrylamide, furan, various aldehydes and 4‐methylimidazole, result from the Maillard Browning Reaction, and California's Proposition 65 law has targeted these carcinogens in coffee. While we must evaluate the toxicological risks of these individual carcinogens, it is equally important to fully evaluate the safety of whole foods containing them using modern clinical, toxicological, nutritional and epidemiological techniques. Currently there is little human epidemiologic evidence linking these trace level carcinogens with the risk of disease, including cancer. The health benefits of a food such as coffee, including numerous health‐protective compounds found naturally and those produced by heat, are often neglected by public health and regulatory authorities. In fact, coffee consumption has been shown to reduce the risk of several human cancers, in spite of the fact that coffee contains many animal carcinogens, a situation I call the Coffee ‐ Cancer Paradox. Therefore, it is critical to evaluate the beneficial health effects of heated foods/beverages and to undertake a thorough risk‐benefit evaluation of the whole food. For carcinogens, this evaluation must carefully consider how best to interpret animal cancer bioassays for individual chemicals, as well as epidemiological information that the whole food itself may actually be cancer protective.

Causal diagrams in systems epidemiology

Methods of diagrammatic modelling have been greatly developed in the past two decades. Outside the context of infectious diseases, systematic use of diagrams in epidemiology has been mainly confined to the analysis of a single link: that between a disease outcome and its proximal determinant(s). Transmitted causes ("causes of causes") tend not to be systematically analysed.The infectious disease epidemiology modelling tradition models the human population in its environment, typically with the exposure-health relationship and the determinants of exposure being considered at individual and group/ecological levels, respectively. Some properties of the resulting systems are quite general, and are seen in unrelated contexts such as biochemical pathways. Confining analysis to a single link misses the opportunity to discover such properties.The structure of a causal diagram is derived from knowledge about how the world works, as well as from statistical evidence. A single diagram can be used to characterise a whole research area, not just a single analysis - although this depends on the degree of consistency of the causal relationships between different populations - and can therefore be used to integrate multiple datasets.Additional advantages of system-wide models include: the use of instrumental variables - now emerging as an important technique in epidemiology in the context of mendelian randomisation, but under-used in the exploitation of "natural experiments"; the explicit use of change models, which have advantages with respect to inferring causation; and in the detection and elucidation of feedback.

Hospital Cluster of HBV Infection: Molecular Evidence of Patient-to-Patient Transmission through Lancing Device

IntroductionIn western countries the transmission of hepatitis B virus (HBV) transmission through multi-patients lancing devices has been inferred since early ‘90s, however no study has ever provided biological evidence which directly link these device with HBV cross-infection. Here we present results of an outbreak investigation which could associate, by molecular techniques, the use of lancing device on multiple patients with HBV transmission in an Italian oncohematology unit.MethodsThe outbreak investigation was designed as a retrospective cohort study to identify all potential cases. All cases identified were eventually confirmed through molecular epidemiology techniques. Audit of personnel including extensive review of infection control measures and reviewing personnel's tests for HBV was done identify transmission route.ResultsBetween 4 May 2006 and 21 February 2007, six incident cases of HBV infection were reported among 162 patients admitted in the oncohematology. The subsequent molecular instigation proved that 3 out 6 incident cases and one prevalent cases (already infected with HBV at the admission) represented a monophyletic cluster of infection. The eventual environmental investigation found that an identical HBV viral strain was present on a multi-patients lancing device in use in the unit and the inferential analysis showed a statistically significant association between undergoing lancing procedures and the infection.DiscussionThis investigation provide molecular evidence to link a HBV infection cluster to multi-patients lancing device and highlights that patients undergoing capillary blood sampling by non-disposable lancing device may face an unacceptable increased risk of HBV infection. Therefore we believe that multi-patients lancing devices should be banned from healthcare settings and replace with disposable safety lancets that permanently retract to prevent the use of the same device on multiple patients. The use of non-disposable lancing devices should be restricted to individual use at patients' home.

Real-Time Molecular Epidemiology of Tuberculosis by Direct Genotyping of Smear-Positive Clinical Specimens

We applied MIRU-VNTR (mycobacterial interspersed repetitive-unit-variable-number tandem-repeat typing) to directly analyze the bacilli present in 61 stain-positive specimens from tuberculosis patients. A complete MIRU type (24 loci) was obtained for all but one (no amplification in one locus) of the specimens (98.4%), and the allelic values fully correlated with those obtained from the corresponding cultures. Our study is the first to demonstrate that real-time genotyping of Mycobacterium tuberculosis can be achieved, fully transforming the way in which molecular epidemiology techniques can be integrated into control programs.

Study and analysis of the state of rare disease research in Shandong Province, China

As the world's most populous country, China has the world's largest number of rare disease groups in terms of prevalence. However, the country has no system of registering cases of most rare diseases, so there is very little documented information on the epidemiology of those diseases. The purpose of this study was to study the state of rare disease research and survey doctors in Shandong Province regarding their level of awareness of rare diseases. Types of rare diseases and numbers of cases were tallied and their geographical distribution over the decades was analyzed. Eight hundred and twenty-four doctors in tertiary hospitals and maternity and child care hospitals were surveyed by questionnaire. Data were descriptively analyzed and a map of disease distribution was created. Articles about rare diseases were retrieved from the Chinese Biomedical Literature Database to provide pertinent data. This study yielded 5,749 cases of 323 different types of rare diseases. The survey found that doctors lack awareness of research on rare diseases. An authoritative and information-rich platform for rare disease research is urgently needed. Key steps are to study epidemiological and statistical techniques and then obtain available data to provide a basis for the definition and regulation of rare diseases in China.

Overview of silkworm pathology in China

In this study, we elaborated the history and progress of studies on silkworm diseases in China through summarizing and reviewing the achievements on silkworm pathology, pathogenic molecular biology, epidemiology, pathogen detection and diagnostic techniques, damage from non-infectious silkworm diseases and control of non-infectious silkworm diseases. These summaries and reviews would provide good references for further studies in silkworm diseases. Key words : Silkworm, pathology, disease control, China.

Factors associated with recently transmitted Mycobacterium tuberculosis strain MS0006 in Hinds County, Mississippi.

The objective of this study was to investigate risk factors associated with tuberculosis (TB) transmission that was caused by Mycobacterium tuberculosis strain MS0006 from 2004 to 2009 in Hinds County, Mississippi. DNA fingerprinting using spoligotyping, mycobacterial interspersed repetitive unit, and IS6110-based restriction fragment length polymorphism of culture-confirmed cases of TB was performed. Clinical and demographic factors associated with strain MS0006 were analyzed by univariate and multivariate analysis. Of the 144 cases of TB diagnosed during the study period, 117 were culture positive with fingerprints available. There were 48 different strains, of which 6 clustered strains were distributed among 74 patients. The MS0006 strain accounted for 46.2% of all culture-confirmed cases. Risk factors for having the MS0006 strain in a univariate analysis included homelessness, HIV co-infection, sputum smear negativity, tuberculin skin test negativity, and noninjectable drug use. Multivariate analysis identified homelessness (odds ratio 7.88, 95% confidence interval 2.90-21.35) and African American race (odds ratio 5.80, 95% confidence interval 1.37-24.55) as independent predictors of having TB caused by the MS0006 strain of M. tuberculosis. Our findings suggest that a majority of recently transmitted TB in the studied county was caused by the MS0006 strain. African American race and homelessness were significant risk factors for inclusion in the cluster. Molecular epidemiology techniques continue to provide in-depth analysis of disease transmission and play a vital role in effective contact tracing and interruption of ongoing transmission.

Real World Occupational Epidemiology, Part 2: A Visual Interpretation of Statistical Significance

Tests of significance in contingency tables represent one of the most useful techniques in occupational epidemiology, and one from which odds ratios (ORs) can be derived to illustrate the probabili...

Epidemiology of IBD and Mortality and Morbidity Outcomes

Purpose: Clinicians at our hospital routinely deal with Inflammatory Bowel Disease (IBD) inpatients. However, no database existed to evaluate IBD prevalence, assess demographic variability, mortality, co-morbid associations and consult burden on other specialties. We embarked on this first of its kind study at our hospital to gather this unique and extensive data which can be further analyzed locally and nationally. Methods: We retrospectively reviewed charts of all 197 IBD patients who were admitted at our hospital from 2007-2010. Data gathering beyond 2007 was not performed because of the logistic challenge of retrieving old charts. Results: Prevalence of Ulcerative Colitis (UC) was higher than Crohn's disease (CD) in our patients which correlates with the national prevalence pattern. Both UC and CD had a female predominance being 60% and 63%, respectively. Interestingly, national figures show an unexplained increase of male predominance in UC patients. A typical “bimodal” distribution of age for IBD was noted in both UC and CD in contrast to a more nationwide emerging pattern of unimodal peak for CD followed by a steady decrease. Both UC and CD were predominantly common among African-Americans than Caucasians. However, other minority groups as Asians and Hispanics were at par with African Americans (38 % vs 38%) in UC and exceeded the number for CD (53% vs 28%). Smoking rates were comparable between UC and CD patients (13% vs 15%). All cause inpatient mortality rates for UC and CD were 4.6% and 0%, respectively. Approximately half of the IBD inpatients had a CT performed and the majority, about 90%, had pertinent findings which did not necessary always alter the diagnostic or therapeutic course of the disease. Surgical consults were called more often for CD than UC patients, 34% vs 20% of the time but not many had an actual surgical intervention. GI consult was almost always invariably called for both UC and CD patients. For both IBD subsets, only about 40% patients had an inpatient colonoscopy with 90-100% chance of positive findings. Both for UC and CD, 65% patients never had a stool CDiff ordered. However, C-Diff predominance was seen in UC compared to CD, 8.5% vs 3%, in subset of IBD patients who did actually get a stool sampling done for C-Diff. Conclusion: The Crohn's and Colitis Foundation of America attributes the lack of epidemiological databases as a particular constraint in IBD related research. Creation and maintenance of such databases would provide new opportunities to apply standard and innovative epidemiological techniques to monitor IBD prevalence, discover the etiologies of IBD, assess estimates of resource utilization and define populations at greatest or least risk.

Aplicación del estimador intrínseco a tasas de mortalidad por cáncer de mama

Assess use of the intrinsic estimator (IE) technique in epidemiology. The IE approach was applied to the analysis of breast cancer data in Argentina in order to observe the trends associated with "age, period, and cohort" (APC). This method involves the use of a principal components regression to obtain a single set of estimated trends. The results were compared to the findings obtained with the conventional method, which consists of adjusting a generalized linear model that includes the traditional constraints of the statistical model as well as an additional constraint (CGLM). Both methods yielded compatible results in the trends associated with APC. However, they differed in the confidence intervals, with IE yielding greater efficiency. The curve associated with age showed the expected pattern of change across the life course: the greater the age, the greater the risk. With regard to cohorts, a decrease in the effects associated with the most recent cohorts was evident, whereas there was very little variation in the estimated effects for the period. A comparison of the results obtained with the IE method and the CGLM method revealed the reach of the generic solution provided by the IE to the problem of estimates in an APC model. The IE method is based on conversion of the data observed using a weighting matrix that is simple to apply and provides estimates with desirable statistical properties.

O6-2.5 Alcohol and prostate cancer risk: a mendelian randomisation approach

IntroductionDespite alcohol being an established carcinogen and recent prospective studies showing increased prostate cancer risk among heavy drinkers, alcohol is not an established risk factor for prostate cancer.We aimed to...

The relationship between lay and technical views of Escherichia coli O157 risk

Here, we bring together and contrast lay (accessible primarily through social science methodologies) and technical (via risk assessment and epidemiological techniques) views of the risk associated with the Escherichia coli O157 pathogen using two case study areas in the Grampian region of Scotland, and North Wales. Epidemiological risk factors of contact with farm animals, visiting farms or farm fields and having a private water supply were associated with postcode districts of higher than average disease incidence in the human population. However, this was not the case for the epidemiological risk factor of consumption of beef burgers, which was independent of disease incidence in the postcode district of residence. The proportion of the population expressing a high knowledge of E. coli O157 was greatest in high-incidence disease districts compared with low-incidence areas (17% cf. 7%). This supports the hypothesis that in high-disease-incidence areas, residents are regularly exposed to information about the disease through local cases, the media, local social networks, etc. or perhaps that individuals are more likely to be motivated to find out about it. However, no statistically significant difference was found between high- and low-incidence postcode districts in terms of the proportion of the population expressing a high likelihood of personal risk of infection (10% cf. 14%), giving a counterintuitive difference between the technical (epidemiological and quantitative microbiological risk assessment (QMRA)) and the lay assessment of E. coli O157 risk. This suggests that lay evaluations of E. coli O157 risk reflect intuitive and experience-based estimates of the risk rather than probabilistic estimates. A generally strong correspondence was found in terms of the rank order given to potential infection pathways, with environment and foodborne infection routes dominating when comparing public understanding with technical modelling results. Two general conclusions follow from the work. First, that integrative research incorporating both lay and technical views of risk is required in order that informed decisions can be made to handle or treat the risk by the groups concerned (e.g. the public, policy makers/risk managers, etc.). Second, when communicating risk, for example, through education programmes, it is important that this process is two-way with risk managers (e.g. including Food Standards Agency officials and communications team, public health infection control and environmental health officers) both sharing information with the public and stakeholder groups, as well as incorporating public knowledge, values and context (e.g. geographical location) into risk-management decisions.

Update on Geographic Atrophy in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the main cause of legal blindness in older patients in developed countries, and geographic atrophy (GA) represents the advanced form of dry AMD. Although it accounts for one third of the cases of late AMD and is responsible for 20% of the cases of severe visual loss due to the disorder. GA currently lacks effective treatment, whereas antiangiogenic therapies have been shown to be successful in managing choroidal neovascularization, the other form of late AMD. Recent advances in GA epidemiology, etiology, genetics, and imaging techniques have renewed the interest in this entity, which is a cause of progressive visual loss even in treated patients with neovascular AMD. This knowledge has triggered many clinical trials targeting different molecules shown to be associated with the disease, and it is hoped that this research will translate into effective drugs for GA in the near future.

Perimetry, tonometry and epidemiology: the fate of glaucoma management

This is the lecture that I gave when I was awarded Acta Ophthalmologica's gold medal and honorary award at the Nordic Ophthalmological Congress in Reykjavik in August 2010. I was inspired by Jared Diamond's famous book: Guns, Germs, and Steel, The Fates of Human Societies. Diamond is professor of geography and physiology at the University of California, Los Angeles. In this book, which won the Pulitzer Prize, the author explains why the European civilization took over the world. This was all because of predetermined factors of biological nature, environmental differences that were strengthened by feedback loops, and resulted in technological innovation and superiority. In this presentation, I write about the development of glaucoma knowledge and management. I suggest that the development might have been predetermined, just waiting for more facts to be unveiled by research. The technologies tonometry and perimetry have been fundamental as has epidemiological techniques and controlled trials. The new and increased knowledge about glaucoma must now be translated to improvements of clinical glaucoma care. The glaucoma scientists of today and tomorrow will continue to reveal as yet unknown facts, maybe in a predetermined way, but nevertheless of benefit to all patients with glaucoma.

Exploring the use of molecular epidemiology to track bovine tuberculosis in Nigeria: An overview from 2002 to 2004

Tuberculosis remains a major public health problem in Nigeria. While human to human transmission of Mycobacterium tuberculosis is clearly of major importance in driving the tuberculosis epidemic in Nigeria, the impact of Mycobacterium bovis transmission from infected cattle is largely unknown. Molecular epidemiology of M. bovis in Nigeria will increase our understanding of this endemic disease and provide tools to assess cattle-to-human transmission. Between 2002 and 2004, molecular techniques including spoligotyping, variable number of tandem repeats (VNTR) typing and deletion typing were used to track and analyze a sample of strains of the M. tuberculosis complex circulating in the cattle population in Ibadan, Southwestern Nigeria. In all, 180 isolates were typed with a view to elucidating epidemiological information on circulating strains, occurrence of transborder transmission and molecular diversity of the M. bovis strains. Results obtained showed that 99% (178/180) of the isolates were M. bovis, while the remaining were M. tuberculosis and M. africanum. In all, strains of M. bovis had 34 different spoligotypes: strains with spoligotype pattern SB0944 (as designated by www.mbovis.org) were the most common (46% of strains). This molecular type is also common in countries neighbouring Nigeria. Strains with this spoligotype pattern could be further divided into 40 different VNTR types. This analysis shows the value of simple molecular epidemiological techniques applied to strains of M. bovis and suggests that further epidemiological studies will shed more light on the transmission dynamics of bovine tuberculosis locally and across neighbouring African countries.

Gender differences in affective suffering among racial/ethnically diverse, community-dwelling elders

Objective. Copious research shows a female excess of unipolar depression. The generalizability of this finding is examined in a racial/ethnically diverse, community-residing, elder sample. Design. Depressive suffering was assessed both categorically and linearly with the Index of Affective Suffering (IAS), a hierarchal measure designed to examine intensity and extensity of suffering. In-home interviews by specially trained raters also collected demographic, functional, and social health data. Prevalence rates of affective suffering were examined separately for Latinos (N=996, Females=46.8%), Blacks (N=717, Females=36.5%), and Whites (N=415, Females=18.6%). Results. Analyzed by gender alone these data support the typical wisdom that females report significantly more depressed affect than males. However, by racial/ethnic group categorical analysis indicates that among Whites and Latinos, women reported more symptoms of clinically significant affective suffering than males; whereas, among Blacks, women and men did not differ from each other. Moreover, risk factors commonly associated with excess female depression failed to explain observed differences. Conclusion. The absence of a between-gender difference in affective suffering observed among Black elders in this study raises questions about generalized assumptions of greater ‘female’ vulnerability for this age group. A need for research to appreciate the heterogeneity of elder individuals is highlighted as is the importance of using dimensional assessment techniques in psychiatric epidemiology.

Personalized nutrigenomics: tailoring the diet to the aging diabesity population

Personalized nutrigenomics: tailoring the diet to the aging diabesity population Douglas M Ruden1, Xiangyi Lu21Wayne State University, Department of Obstetrics and Gynecology, C. S. Mott Center for Human Growth and Development, Institute of Environmental Health Sciences, Detroit, MI, USA; 2Institute of Environmental Health Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Detroit, MI, USAAbstract: According to the International Diabetes Federation (IDF), 190 million people worldwide suffer from diabetes, and this number is estimated to double by the year 2025. Diabetes is especially prominent in the elderly population because the IDF indicates age above 45 years as a major risk factor for diabetes. The most common trials for controlling diabetes focus on tighter glucose control as a means to reduce the long-term complications. However, whether tight blood sugar control or other dietary or pharmaceutical interventions in the elderly are more appropriate is not known. Major changes have taken place in our diet over the past 10,000 years since the beginning of the Agricultural Revolution, but our genes have not changed. Furthermore, the large numbers of diabetic elderly in the population are a recent phenomenon, because those with diabetes have historically died young. Genetically speaking, humans today live in a nutritional environment that differs from that for which our genetic constitution was selected. For example a high omega-6/omega-3 ratio, found in today’s Western diets, promotes the pathogenesis of many chronic diseases, including cardiovascular disease and diabetes. Knowing who is at risk would be useful if it meant that one could avoid the environmental triggers that convert susceptibility to disease. The prospect of targeting specific dietary treatments at the elderly, who are predicted to gain the most therapeutic benefits, clearly has important clinical and economic consequences. In this review, we will discuss modern molecular genetic and epidemiological techniques which are now, or soon will be, made available by inexpensive whole-genome sequencing and other whole genome approaches to treat the elderly diabetic population.Keywords: diabetes, elderly diabetic population, DNA, genome sequencing 

Epidemiology in a changing world: variation, causation and ubiquitous risk factors

We are all living in the era of globalization and, like it or not, it is going to change the way we practise epidemiology, the kinds of questions we ask and the methods we use to answer them. However, the methods, and ways of thinking about the health of populations, that will be required for epidemiology in the 21st century are in some instances quite different from the standard epidemiological techniques that are taught in most textbooks and courses today. As we develop epidemiological methods for addressing the scientific and public health problems of the 21st century, it is important that we consider, once again, the distinction between the analysis of variance and the analysis of causes. This has primarily been considered with respect to genetic research, and also with regard to the problems of making comparisons between different populations and environments at the same point in time. It has not been considered in depth with regard to the issues of conducting epidemiological research in a world that is changing over time. In this article, I first consider the statistical and scientific issues involved in the distinction between the analysis of variance and the analysis of causes. I then discuss some examples of the implications of this distinction for the theory and practice of epidemiology in a changing world, particularly with regard to risk factors that become ubiquitous over time. Sometimes the most important causes of disease are invisible because they are everywhere.

The Effect of Heatwaves on Ambulance Callouts in Adelaide, South Australia

O-29A1-6 Background/Aims: Although many studies have noted the association between high ambient temperatures and increases in hospital admissions and mortalities, relatively few have investigated the effect on ambulance services, a useful supplement to other morbidity data. The aim of this study was to investigate the effect of heatwaves on ambulance callouts and to identify heat-susceptible areas of the city of Adelaide, South Australia. Methods: Ambulance service data and meteorological data relevant to the metropolitan area were obtained for the period between 1 July 1993 and 30 June 2005. Heatwaves in the warm season (October to March) were defined as being 3 or more consecutive days when daily maximum temperatures reached or exceeded 35°C. Statistical analysis of callouts was undertaken by comparing heatwave to non-heatwave periods using negative binomial regression accounting for overdispersion and long-term trends. Using destination postcodes of callouts, spatial epidemiological techniques investigated place-based risk. Exposure analysis was undertaken by determining threshold temperatures using non-linear least squares estimation. Results: Ambulance callouts increased by 3.6% during heatwaves compared to non-heatwave periods in the warm season, with an increase of 2.6 callouts per 1 degree C increase in daily maximum temperature above a threshold of 34.6°C. Industrial suburbs and those with a high proportion of low income families were identified as heat-sensitive regions of the metropolitan area. Cause-specific attendances varied between suburbs with some recording an increase of more than three-fold in work-related callouts during heatwaves. Conclusion: In the absence of population adaptation to warmer summers, ambulance and other emergency services may be in greater demand should heatwaves become more frequent and intense with a changing climate. Strategies required to mitigate the negative health effects of extreme heat may need to be targeted towards susceptible sub populations, communities art risk, and industrial workplaces.