Severe acute respiratory syndrome (SARS) was defined as an invasive respiratory disease in 2002, which originally came from China and rapidly spread all over the globe. Acute pneumonia and lower respiratory tract involvement most affected the middle aged individuals and elderly with a mortality rate of 11%. While SARS Corona virus (SARS-CoV) has maintained its potential capacity to reemerge, clinical study of the immune system of SARS patients, as well as controlled studies may lead to application of new treatment strategies in future. Throughout this work, I have focused on early immune responses to SARS-CoV in humans and in ferrets. CXCL0 has been associated with alterations in the clinical course of several infectious diseases, including SARS and influenza. Here I have cloned ferret CXCL10 gene and have expressed its recombinant protein. I demonstrate that the CXCL10 plasma level in SARS patients is associated with the severity of disease. I also show that endogenous ferret CXCL10 exhibits similar mRNA expression patterns in the lungs of deceased SARS patients and ferrets experimentally infected with SARS-CoV. Type I interferons (IFNs) are indispensable parts of the innate immunity during early stages of infection. A clear distinction between genes upregulated by direct virus-cell interactions and genes upregulated by secondary IFN production has not been made yet. Here, I have investigated differential gene regulation in ferrets upon subcutaneous administration of IFN-a2b and during SARS-CoV infection. In vivo experiments revealed that IFN-a2b causes upregulation of abundant IFN response genes (IRGs), chemokine receptors, and other genes that participate in phagocytosis and leukocyte migration. SARS-CoV infection of ferrets leads to upregulation of varieties of IRGs and a broad range of genes involved in cell migration and inflammation. This work allowed dissection of several molecular signatures present during SARS-CoV infection, which are part of a robust IFN antiviral response. Since localization of CD8+ Tcells may contribute to tissue injury, I have characterized ferret CD8 gene and have generated reagents that can be used in future studies with the aim of evaluating CD8+ T cells localization in the ferret lung during infection with SARS-CoV.

Herpetic stromal keratitis (HSK) is an immunopathological and tissue destructive corneal lesion caused by herpes simplex virus (HSV) infection, which induces an intense inflammatory response and finally leads to blindness. Accumulating evidence using the murine model has shown that Th-1 phenotype CD4+ T cells orchestrating the inflammation mainly contribute to the immunopathological reaction in HSV-1 infected cornea. Initially various innate immune cells recruit and produce numerous inflammatory and angiogenic molecules into the corneal stroma those in turn drive the corneal immunopathology. While the basic principles of immunity to the influenza A viruses (IAV) are probably similar for all vertebrates, detailed understanding is based largely on experiments in laboratory mice. Virus clearance is normally mediated via CD8+ effector T cells but, in their absence, the class-switched antibody response can ultimately achieve the same goal. Influenza virus-specific plasma cells and CD8+ T cells persist in the long term and the recall of the CD8+ T cell response can lead to earlier virus clearance. The first part (Part I) of this dissertation focuses on the understanding of HSV-1 induced immunoinflammatory processes in the cornea and the secondary lymphoid tissues and the involvement of immuno-modulatory mechanisms following acute viral infections such as HSV and IAV. The next three parts (Part II-IV) focus on different inflammatory and counter-inflammatory mechanisms that are activated following acute viral infections. Results in Part II evaluate the role of small molecule inhibitors of VEGFR2/src kinase inhibitors in controlling the progression of the inflammatory lesions after ocular HSV infection. Results of the third section show that the host counter inflammatory mechanisms inhibit tissue damage but these may also act to constrain the effectiveness of immunity to acute infections. The fourth section describes the functional significance of HVEM expression on regulatory T cell in their expansion following HSV-1 infection. In this study, experiments were designed to understand the mechanisms involved in the regulation of immunity and resultant immunopathology using HSV-1 and IAV as the model systems and that modulation of these processes can enhance immune response and diminish immunopathology following acute infections.

Drug resistance is a major obstacle to management and control of malaria and currently progressing at a rapid rate across Africa. This thesis has examined factors influencing evolution of resistant P. falciparum at two sites in Africa, including parasite migration, cross mating and fitness cost of resistance. In Asar village, eastern Sudan, the frequencies of drug sensitive and resistant parasites were monitored throughout the dry season in the absence of anti-malarial drug usage to examine whether persistence of resistant parasites is reduced in the absence of drug pressure. Two cohorts of P. falciparum infected patients were treated with chloroquine in the transmission season (Oct-Dec), and followed monthly in the dry season into the next transmission season. A large proportion of the cohort maintained sub-patent asymptomatic P. falciparum infections throughout the entire study period. Alleles of the chloroquine resistance transporter (Pfcrt) and multi-drug resistance protein (Pfmdr1) were examined. Mutant alleles of Pfcrt reached fixation following CQ treatment and remained high in the transmission season. However, at the start of the dry season, wild type alleles of both genes started to emerge and increased significantly in frequency as the season progressed. The mutant Pfcrt haplotype was invariably CVIET, indicating migration of CQ resistant parasites into an area; otherwise the CVMNK haplotype is normal. In addition, microsatellite haplotypes of dihydrofolate reductase (dhfr) gene and dihydropteroate synthase (dhps) genes, which control the parasite response to pyrimethamine and sulfadoxine respectively, were characterized. One major dhfr haplotype with double dhfr mutations and two major mutant dhps haplotypes were seen in eastern Sudan. These haplotypes are distinct from those prevailing in other African countries, suggesting the likely local origin of dhfr and dhps haplotypes conferring drug resistance. Transmission capacities of different P. falciparum clones within a single infection in The Gambia have a high ability to produce gametocytes and infect Anopheles mosquitoes even when they exist at levels not detectable by microscopy and PCR. These findings emphasize the crucial role of gametocyte complexity and infectivity in generating the remarkable diversity of P. falciparum genotypes seen in infected people. Parasites with different resistant dihydrofolate reductase (dhfr) haplotypes have the ability to infect Anopheles mosquitoes following drug treatment, and cross-mating between parasites with different dhfr haplotypes was detected. Our results showed that the major dhfr haplotype in the Gambia is similar to the common one seen in other African countries, suggesting that parasite migration plays a major role in spread of resistance. Indeed, the dominant resistant haplotype seen in infected patients was readily transmitted to infect mosquitoes.

No description available.

Arthropod parasites and micropredators, such as ticks and mosquitoes, influence terrestrial ecosystems and harm their hosts directly and indirectly by vectoring micro-organisms. Whether micropredators similarly affect marine ecosystems and hosts is not well understood. In coral reef fish communities, the most abundant micropredators are isopods, in particular, gnathiids. Our understanding of how isopods affect fishes has been restricted by a lack of information regarding basic isopod biology including; patterns of abundance, parasite identity, host specificity and host pathology. Also it is unknown if small juvenile fish are parasitised by isopods, and if this affects their survival. Sequentially, the aims of my PhD thesis were to understand the ecology of several lesser known parasites in sufficient detail to perform manipulative experiments that could test the effects of micropredation on small juvenile reef fish. All field studies took place at Lizard Island, Great Barrier Reef My first study aimed to describe temporal and spatial patterns of isopod abundance by measuring emergence rates. Gnathiid isopod juveniles emerge from the benthos into the water column to find hosts or change locations. Although diel patterns have been demonstrated, the relationship between substrate and emergence on coral reefs is not clear. I measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in 6 “habitats” at 2 very different sites at Lizard Island. Isopods were collected from the periphery and centres of 3 sizes of reef, and from the substrate between these reefs (sand or rubble). At both sites, the most abundant gnathiid species (Gnathia falcipenis and Gnathia sp C), was exclusive to that site. Although strong diel patterns in emergence were observed, gnathiid abundance could not be predicted by habitat. However, gnathiids were larger and more often fed over reef borders than in the centres of reefs. To explain these patterns, I suggested that first stage larvae had the largest influence on total abundance and were patchily distributed in accordance with adults from which they had recently hatched. As later stage larvae also depend on fish, more successful (fed and older larvae) are found on the edges of reefs where appropriate hosts may be more abundant. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicated that gnathiid distribution may be better predicted by very fine scale differences in substrate, or that larvae are simply gregarious, and that abundance may be difficult to predict on the basis of substrate. Without reliable differences in parasite abundance among habitats at Lizard Island, subsequent studies would rely on manipulating parasite abundance via excluding wild parasites in the field (which proved very difficult) or by controlling abundance in laboratory simulations. I then investigated host specificity in the 2 most abundant gnathiid species from the previous study. Discrete species distributions between the two sites suggested that the 2 parasites may have had different diets. Host-specificity data for gnathiid isopods are scarce because the parasitic juvenile stages are difficult to identify and host-parasite contact is often brief. Engorged third stage gnathiids were photographed and permitted to moult into adults to allow identification. I compared mtDNA sequences from their blood meals to host sequences available on GenBank. The host frequency distributions used by each species were significantly different; only four host families were shared. I concluded that G. falcipenis and Gnathia sp C operate as preferential feeders. Importantly, this work showed that G. falcipenis was indeed a natural parasite of several species of damselfish (Pomacentridae) that could be collected as young recruits and used in manipulative experiments. I then used G. falcipenis as a model parasite to investigate the effects of isopods on recently recruited Dischistodus perspicillatus and small juvenile Acanthochromis polyacanthus damselfishes. Working with honours student Ms Rose Penfold, we determined that A. polyacanthus was infected by gnathiids in the wild at sizes as small as 4.2 mm SL. Laboratory infections revealed that larger A. polyacanthus were much better at eating gnathiids, a behaviour which prevented infection, and that smaller fish were more likely to die post-infection. Infection prevalence was > 3 % during the day, but we could not sample fish for nocturnal infection prevalence. A caging experiment suggested that most micropredation on damselfish took place at night. For D. perspicillatus, I found that exposure to 2 parasites each evening for 7 nights after settlement halved the growth of these fish. Lastly, numerous free-swimming cymothoid isopods were found associated with larval fish in light traps. Cymothoids have a multi-morphic life cycle composed of micropredatory stages that eventually become females, which are permanently attached to fishes. Because cymothoid taxonomy is based around female morphology, natatory-stage cymothoids can not be identified. I sequenced mtDNA from natatory and adult female life history stages and matched 4 of 11 natatory cymothoid morphotypes. Molecular data were also used to produce a phylogeny exploring the evolution of different forms of host attachment within the Cymothoidae. This phylogeny suggests that external attachment, formerly thought to be plesiomorphic, is a derived condition and has evolved several times independently. I suggest that attachment to the buccal cavity or gills is a primitive form of attachment. This research has provided information on emergence patterns and hostspecificity which is necessary for the future study of isopod vector biology. It also provides a platform for future taxonomic and phylogenetic studies on cymothoids. I demonstrate that gnathiids infect juvenile coral reef fish and suggest that they may influence survival both directly and indirectly by reducing growth and predisposing infected fish to size-selective mortality. Thus, interactions between isopod micropredators and recruiting fishes may determine the survivorship of individual fish and influence the subsequent community structure.

Arthropod parasites and micropredators, such as ticks and mosquitoes, influence terrestrial ecosystems and harm their hosts directly and indirectly by vectoring micro-organisms. Whether micropredators similarly affect marine ecosystems and hosts is not well understood. In coral reef fish communities, the most abundant micropredators are isopods, in particular, gnathiids. Our understanding of how isopods affect fishes has been restricted by a lack of information regarding basic isopod biology including; patterns of abundance, parasite identity, host specificity and host pathology. Also it is unknown if small juvenile fish are parasitised by isopods, and if this affects their survival. Sequentially, the aims of my PhD thesis were to understand the ecology of several lesser known parasites in sufficient detail to perform manipulative experiments that could test the effects of micropredation on small juvenile reef fish. All field studies took place at Lizard Island, Great Barrier Reef My first study aimed to describe temporal and spatial patterns of isopod abundance by measuring emergence rates. Gnathiid isopod juveniles emerge from the benthos into the water column to find hosts or change locations. Although diel patterns have been demonstrated, the relationship between substrate and emergence on coral reefs is not clear. I measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in 6 “habitats” at 2 very different sites at Lizard Island. Isopods were collected from the periphery and centres of 3 sizes of reef, and from the substrate between these reefs (sand or rubble). At both sites, the most abundant gnathiid species (Gnathia falcipenis and Gnathia sp C), was exclusive to that site. Although strong diel patterns in emergence were observed, gnathiid abundance could not be predicted by habitat. However, gnathiids were larger and more often fed over reef borders than in the centres of reefs. To explain these patterns, I suggested that first stage larvae had the largest influence on total abundance and were patchily distributed in accordance with adults from which they had recently hatched. As later stage larvae also depend on fish, more successful (fed and older larvae) are found on the edges of reefs where appropriate hosts may be more abundant. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicated that gnathiid distribution may be better predicted by very fine scale differences in substrate, or that larvae are simply gregarious, and that abundance may be difficult to predict on the basis of substrate. Without reliable differences in parasite abundance among habitats at Lizard Island, subsequent studies would rely on manipulating parasite abundance via excluding wild parasites in the field (which proved very difficult) or by controlling abundance in laboratory simulations. I then investigated host specificity in the 2 most abundant gnathiid species from the previous study. Discrete species distributions between the two sites suggested that the 2 parasites may have had different diets. Host-specificity data for gnathiid isopods are scarce because the parasitic juvenile stages are difficult to identify and host-parasite contact is often brief. Engorged third stage gnathiids were photographed and permitted to moult into adults to allow identification. I compared mtDNA sequences from their blood meals to host sequences available on GenBank. The host frequency distributions used by each species were significantly different; only four host families were shared. I concluded that G. falcipenis and Gnathia sp C operate as preferential feeders. Importantly, this work showed that G. falcipenis was indeed a natural parasite of several species of damselfish (Pomacentridae) that could be collected as young recruits and used in manipulative experiments. I then used G. falcipenis as a model parasite to investigate the effects of isopods on recently recruited Dischistodus perspicillatus and small juvenile Acanthochromis polyacanthus damselfishes. Working with honours student Ms Rose Penfold, we determined that A. polyacanthus was infected by gnathiids in the wild at sizes as small as 4.2 mm SL. Laboratory infections revealed that larger A. polyacanthus were much better at eating gnathiids, a behaviour which prevented infection, and that smaller fish were more likely to die post-infection. Infection prevalence was > 3 % during the day, but we could not sample fish for nocturnal infection prevalence. A caging experiment suggested that most micropredation on damselfish took place at night. For D. perspicillatus, I found that exposure to 2 parasites each evening for 7 nights after settlement halved the growth of these fish. Lastly, numerous free-swimming cymothoid isopods were found associated with larval fish in light traps. Cymothoids have a multi-morphic life cycle composed of micropredatory stages that eventually become females, which are permanently attached to fishes. Because cymothoid taxonomy is based around female morphology, natatory-stage cymothoids can not be identified. I sequenced mtDNA from natatory and adult female life history stages and matched 4 of 11 natatory cymothoid morphotypes. Molecular data were also used to produce a phylogeny exploring the evolution of different forms of host attachment within the Cymothoidae. This phylogeny suggests that external attachment, formerly thought to be plesiomorphic, is a derived condition and has evolved several times independently. I suggest that attachment to the buccal cavity or gills is a primitive form of attachment. This research has provided information on emergence patterns and hostspecificity which is necessary for the future study of isopod vector biology. It also provides a platform for future taxonomic and phylogenetic studies on cymothoids. I demonstrate that gnathiids infect juvenile coral reef fish and suggest that they may influence survival both directly and indirectly by reducing growth and predisposing infected fish to size-selective mortality. Thus, interactions between isopod micropredators and recruiting fishes may determine the survivorship of individual fish and influence the subsequent community structure.

No description available.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 44-49).

BACKGROUND: Infective endocarditis (IE) is an infectious disease, most often bacterial in etiology, which affects the endocardial tissue layer of the heart. Despite advances in diagnostic technology, surgical technique, and antimicrobial therapy, IE remains a high-mortality disease. OBJECTIVE: This is a proposed quality improvement initiative for the Boston Medical Center (BMC) inpatient medicine service. The initiative aims to identify predictors of mortality in patients with IE, and then use the predictors to create a mortality risk-assessment checklist. The checklist will serve as a clinical tool for medicine service providers to help determine if upgrade to ICU level of care is warranted. With early upgrade to an ICU setting, patients with a high risk of mortality will receive more individualized care and expedited medical intervention. The goal of this quality improvement initiative is to decrease mortality rate in patients with IE at BMC. METHODS: This quality improvement initiative will implement the PDSA (plan, do, study, act) model for quality improvement. The checklist will be integrated into the electronic health record system at BMC and will be implemented over a two-year time period. Each PDSA cycle will last one year, and between PDSA cycles the checklist will be modified according to medical provider feedback. The data will be gathered through chart reviews to determine pre and post-checklist differences in number of transfers to the ICU and overall mortality rates of IE patients at BMC. RESULTS: The literature review of this proposed quality improvement initiative has identified nine independent risk factors for mortality in patients with IE: Staphylococcus aureus as infective organism, New York Heart Association class IV heart failure, left ventricular ejection fraction < 40%, vegetation size ≥ 15 mm, age > 50 years, diabetes mellitus, peripheral dermatologic findings on physical examination, serum neutrophil-to-lymphocyte ratio > 5.45, and serum D-dimer level > 4.0 mg/L. CONCLUSION: If medical providers had access to a risk assessment tool to help identify IE patients with a high risk of mortality, they could more accurately determine appropriate level of care, expedite medical intervention, and possibly reduce rates of in-hospital death in patients with IE.

Medical cartography can provide valuable insights into the epidemiology and ecology of infectious diseases, providing a quantitative representation of the distribution of these pathogens. Such methods therefore provide a key step in informing public health policy decisions ranging from prioritising sites for further investigation to identifying targets for interventions. By increasing the resolution at which risk is defined, policymakers are provided with an increasingly informed approach for considering next steps as well as evaluating past progress. In spite of their benefits however, global maps of infectious disease are lacking in both quality and comprehensiveness. This thesis sets out to investigate the next steps for medical cartography and details the use of species distribution models in evaluating global distributions of a variety of zoonotic diseases of public health importance. Chapter 2 defines a methodology by which global targets for infectious disease mapping can be quantitatively assessed by comparing the global burden of each disease with the demand from national policymakers, non-governmental organisations and academic communities for global assessments of disease distribution. Chapter 3 introduces the use of boosted regression trees for mapping the distribution of a group of vector-borne diseases identified as being a high priority target, the leishmaniases. Chapter 4 adapts these approaches to consider Ebola virus disease. This technique shows that the West African outbreak was ecologically consistent with past infections and suggests a much wider area of risk than previously considered. Chapter 5 investigates Marburg virus disease and considers the variety of different factors relating to all aspects of the transmission cycle that must be considered in these analyses. Chapters 6 and 7 complete the mapping of the suite of viral haemorrhagic fevers by assessing the distribution of Crimean-Congo haemorrhagic fever and Lassa fever. Finally, Chapter 8 considers the risk that these viral haemorrhagic fevers present to the wider African continent, quantifying potential risk of spillover infections, local outbreaks and more widespread infection. This thesis addresses important information gaps in global knowledge of a number of pathogens of public health importance. In doing so, this work provides a template for considering the global distribution of a number of other zoonotic diseases.