Lübeck, Med. Universität, Thesis (doctoral), 2002.

published_or_final_version / abstract / toc / Medicine / Doctoral / Doctor of Philosophy

The objectives of this dissertation are to (1) propose a conceptual framework describing the role of water in H. pylori transmission; (2) construct a database of water system and environmental characteristics using a geographic information system (GIS); (3) investigate the prevalence and incidence of H. pylori-related illnesses; and (4) examine the association between water system and environmental variables and H. pylori infection. The setting for this work was the Township of Langley, British Columbia. Based on findings from epidemiological and microbiological studies, a conceptual model of water’s role in H. pylori transmission was developed (Chapter 2). A population-based approach was employed in the construction of the GIS database to assign the risk factors outlined in the model to each Township resident (Chapter 3). Using administrative health services records for H. pylori-related illness, the average annual prevalence of gastric cancer, peptic ulcer disease and gastritis was 20, 450 and 1,777 cases per 100,000 population respectively, and average annual incidence was 13, 268 and 899 cases per 100,000 respectively. There was a significant decrease in the prevalence and incidence of peptic ulcer disease and the incidence of gastritis in the study population over the follow-up period, however, the costs to the health care system remained high (Chapter 4). In a nested case-control study, variables from the GIS database were linked to a database of serological results used to ascertain positive H. pylori infection. H. pylori infection was associated with mixed water source (adjusted OR = 0.63, versus groundwater only) and non-residential land use (adjusted OR=1.58, versus residential) among younger cases (Chapter 5). Odds ratios diminished in the older age groups, suggesting the presence of a cohort effect and that the exposures investigated were most relevant for younger individuals. The findings highlight possible transmission routes, relevant within the Canadian (and North American) context and evidence for public health interventions with regards to water supply and land use. Further, the methodology linked a variety of administrative data to cover all residents of the study area and assigned environmental variables over time, and can serve as a model for other environmental epidemiologic studies.

The objectives of this dissertation are to (1) propose a conceptual framework describing the role of water in H. pylori transmission; (2) construct a database of water system and environmental characteristics using a geographic information system (GIS); (3) investigate the prevalence and incidence of H. pylori-related illnesses; and (4) examine the association between water system and environmental variables and H. pylori infection. The setting for this work was the Township of Langley, British Columbia. Based on findings from epidemiological and microbiological studies, a conceptual model of water’s role in H. pylori transmission was developed (Chapter 2). A population-based approach was employed in the construction of the GIS database to assign the risk factors outlined in the model to each Township resident (Chapter 3). Using administrative health services records for H. pylori-related illness, the average annual prevalence of gastric cancer, peptic ulcer disease and gastritis was 20, 450 and 1,777 cases per 100,000 population respectively, and average annual incidence was 13, 268 and 899 cases per 100,000 respectively. There was a significant decrease in the prevalence and incidence of peptic ulcer disease and the incidence of gastritis in the study population over the follow-up period, however, the costs to the health care system remained high (Chapter 4). In a nested case-control study, variables from the GIS database were linked to a database of serological results used to ascertain positive H. pylori infection. H. pylori infection was associated with mixed water source (adjusted OR = 0.63, versus groundwater only) and non-residential land use (adjusted OR=1.58, versus residential) among younger cases (Chapter 5). Odds ratios diminished in the older age groups, suggesting the presence of a cohort effect and that the exposures investigated were most relevant for younger individuals. The findings highlight possible transmission routes, relevant within the Canadian (and North American) context and evidence for public health interventions with regards to water supply and land use. Further, the methodology linked a variety of administrative data to cover all residents of the study area and assigned environmental variables over time, and can serve as a model for other environmental epidemiologic studies.

Background: Despite a declining trend in the incidence of gastric cancer (GC), it is still a major global public health concern of the 21st century. It afflicts one million people and kills 750,000 annually. It is believed that both genetic and environmental factors contribute to the gastric carcinogenesis. However geographic variation and immigrant studies highlight the role of environmental factors. Objective: To evaluate the association of GC with the environmental factors of diet, helicobacter pylori (H. pylori) infection, lifestyle and occupation as well as family history in Iran. Methodology: A population based case-control study was conducted in the Northwest of Iran where one of the highest incidence rates of the world has been reported. Two hundred and seventeen cases of GC and 394 age and gender matched controls were recruited. Participants were interviewed using a structured questionnaire which elicited information on demographic characteristics, socioeconomic status, family and medical history, lifestyle (smoking, alcohol drinking and substance abuse) and occupation. Ten milliliters of each subject???s blood was collected for blood grouping and to investigate presence of IgG antibodies against H. pylori using an ELISA kit which had been locally validated for this study. Results: Diet and H. pylori infection were found to be the most important determinants of GC in this study. High intake of allium vegetables and fruit, especially citrus fruit, appears to play a protective role. In addition to the consumption of fruit and vegetables, consumption of fresh fish was also inversely associated with GC. On the other, hand consumption of red meat and dairy products were positively associated with the risk of GC. Other dietary practices were also found to be important factors in the etiology of GC. People who had a preference for higher salt intake and drinking strong and hot tea were at higher risk. Finally, H. pylori infection was found to increase the risk of GC. Conclusion: This study has provided important and original information about the etiology of gastric cancer particularly in the Iranian context. These findings could be used in planning preventive strategies for this malignancy, which is a major health problem in Iran.

Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 4 uppsatser.

Thesis (MSc.(Chemical Pathology)--Faculty of Health Sciences))-University of Pretoria, 2008. / Summary in English and Afrikaans. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 165-168). Also available in print.

Thesis (Ph. D.)--University of Missouri--Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 97-104). Also available on the Internet.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 136-167).