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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Epidemiology, immunology and genetics of viral hepatitis in Aden City, Yemen

Bawazir, Amin Ahmed January 2009 (has links)
Background: Viral hepatitis is a significant public health problem with millions of humans infected worldwide. There are very few studies of hepatitis in Aden, Yemen. Aims: The study aims to determine the prevalence of viral hepatitis (A, B, e and E), their co-infection with Epstein - Barr virus (EBV), cytomegalovirus (eMV) and human herpes virus (HHV6) and the risk factors for HBV infection among individuals attending primary health care facilities. Risk factors for HBV and Hev infection were also identified in patients with chronic liver disease (eLO), multi-transfusions and those undergoing haemodialysis (HO). The genotypes of HBV are studied. The HBV vaccination coverage in children < 5 years in Aden is also described. Methodology: A cross-sectional study of individuals attending primary health care facilities in Aden was conducted to identify the prevalence of the viruses. Participants were recruited stratified by age. A case-control study of hospital patients with eLO, polytransfusion and HO was used to identify risk factors for HBV and Hf'V. Both cases and healthy participants were interviewed and blood samples were analysed using ELISA assays. A community-based survey of children < 5 years was used to identify vaccination coverage and to interview parents. peR sequencing method was used for HBV genotyping. Results: The overall seroprevalence of exposure to HAV (anti-HAV antibodies), HBV (anti-HBc antibodies), HEV (anti-HEV antibodies) and HeV (anti-Hf'V antibodies) were 86.6%, 16.2%, 10.7% and 0.4%, respectively. HBV and Hev had low prevalence in children and no HBV carriage. Perinatal transmission does not seem to be a major route of transmission for HBV. Acupuncture and cupping are risk factors for chronic liver diseases in this setting. The duration of the haemodialysis and a history of malaria were associated with increased rates ofHBV and Hev infections among polytransfusedIHO patients. This is the first report of the prevalence ofEBV, eMV and HHV6 in Yemen. The three viruses had high seroprevalences and co-infections with another herpes virus or hepatitis viruses were common. The Expanded Programme of Immunisations in Aden has achieved HBV vaccination coverage of 63% in children < 5 years old which was lower than its target (85%), but the highest reported in the country. Lack of parental education and access to health care facilities were associated with lack of vaccination. The predominant genotype of hepatitis B was genotype D. Conclusions: Viral hepatitis is a major public health problem in this community. Viruses causing hepatitis varied from hyperendemic (HAV) to low prevalence (HeV); and prevalence varies with age. None of the children < 15 years were HBV carriers or had Hev infection. The detection rates in the study would classify Aden as a low HBV endemic zone. This is the first description of HEV in Yemen revealing it to be a significant problem. Polytransfusion and HO are important risk factors for contracting HBV and Hev. The information yielded in this study on the prevalence and risk factors for HBV and Hev infection on patients with eLO would improve our understanding on the role of these viruses and the application of preventive and control measures in this population.
42

Aspects of pathogenesis of nontyphoidal Salmonella Bacteraemia in Malawian children : a study of pathogen virulence, antibiotic resistance and carriage

Msefula, Chisomo Lawrence January 2009 (has links)
Introduction: Multi-drug resistant (MDR) nontyphoid Salmonellae (NTS) enterica serovars Typhimurium (STM) and Enteritidis (SEN) are a major cause of bacteraemia in children and HIV-infected adults in Malawi. The aims of the investigations were to determine the relatedness and virulence of invasive NTS strains, and the mode of antibiotic resistance, and to assess the level of NTS carriage in healthy asymptomatic adults and children in the community and children admitted to hospital with NTS bacteraemia Methods: Pulse field gel electrophoresis (PFGE), plasmid purification, multilocus sequence typing, whole-genome sequencing, polymerase chain reaction and disk diffusion antibiotic-sensitivity testing were used to characterise NTS isolates. Standard microbiological techniques were used to isolate Salmonellae from stool and the oropharynx. Fitness of pre-2002 and post-2002 STM strains was measured using the serum-bactericidal assay, HEp 2 cell-invasion assay and competitive growth in mice and L8 broth. Results: 90% of STM isolates have one PFGE type and plasmid profile. There is no dominant PFGE and plasmid type among SEN strains. 90% (38/42) of STM strains tested belong to a novel sequence type, ST313. SEN strains belong to the worldwide-reported sequence type, ST11. MDR genes in STM strains are encoded on a large self-transferable virulence plasmid pSL T-8T. Chromosomal deletions and prophage insertions distinguish pre-2002 and post-2002 STM strains. There was no significant difference between pre-2002 and post-2002 STM strains in their capacity to invade HEp-2 cells, in their growth in mice and in their sensitivity to serum killing. An NTS carriage rate of 1.6% (13/824) was found in healthy individuals in the community. Stool and oropharyngeal NTS carriage rates in bacteraemic children were 52% and 36% during admission, 13.2% and 13.7% six weeks later in convalescence. Conclusion: The findings suggest that emergence of MDR among STM in 2002 in Blantyre was a result of the appearance of a new dominant 8TM strain and not acquisition of mobile genetic elements. The results further suggest reductive evolution in the dominant STM strain. There is possibly co-selection of virulence and antibiotic resistance in STM strains. The results also suggest that postbacteraemic children are the reservoir of invasive NTS in the community. A longitudinal study of NTS carriage in post-bacteraemic children in the community needs to be conducted.
43

Identification of factors contributing to the virulence of Haemophilus influenzae biogroup Aegyptius : the causative agent of Brazilian purpuric fever

Heggie, Andrew Martin January 2008 (has links)
No description available.
44

The population biology of Ascaris lumoricoides infections in humans

Walker, Martin January 2010 (has links)
No description available.
45

Intrinsic and extrinsic determinants of Dengue disease variability

Wilson, Anthony January 2007 (has links)
No description available.
46

Investigation of pre-erythrocytic malaria vaccines in a mouse model using transgenic parasites

Watkins, Katherine Ruth January 2005 (has links)
No description available.
47

Host genetic susceptibility to malaria and bacteraemia

Khor, Chiea Chuen January 2005 (has links)
No description available.
48

Mapping the contemporary global distribution limits of malaria using empirical data and expert opinion

Guerra Loaiza, Carlos A. January 2007 (has links)
No description available.
49

High content RNAi screen to identify host factors that regulate phagocytosis of Leishmania donovani amastigotes

Peltan, Adam January 2010 (has links)
No description available.
50

The host genetics of typhoid fever in Vietnam

Hue, Nguyen Thi January 2007 (has links)
No description available.

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