Magister Public Health - MPH / Immunisation is considered to be amongst the most successful and cost-effective disease prevention interventions available. The Expanded Programme on Immunisation (EPI) in Namibia was established in 1990 to ensure that the immunisation of children takes place within the prescribed age frame. However, continued measles outbreaks, particularly in the Kavango region, are evidence of poor EPI progress, with vaccination coverage being below80% per district. The reasons for the low uptake of measles immunisation in the Nyangana district in the Kavango region are not clearly understood. The aim of this study was, therefore, to investigate the perception of mothers/caregivers of factors that impact on the uptake of measles immunisation in the Nyangana Health District, with a view to improving measles immunisation coverage. Methodology: A qualitative exploratory study design was used to collect data from the study participants. In-depth interviews were conducted with 10 mothers of children under 5 years of age, for both children who received, and those who did not receive measles vaccination. Data was audio-taped and transcribed verbatim. The recorded interviews were translated from the Gciriku language to English. Data was analysed through the use of the Thematic Content Analysis approach. The transcribed interviews and narratives from the research assistant’s notes were organised into codes, sub-themes and main themes. In the final phase, themes were integrated and interpreted, by identifying facilitating factors for those who took their children for immunisation, and barriers for those who did not take theirs. The researcher facilitated assistance to children who did not receive their measles dose, to receive it. Ethical requirements were adhered to throughout the research study process. Results: The study showed that mothers had both positive and negative perceptions about immunisation. The findings revealed that information, and past experience of measles ,irrespective of the level of education, support from a spouse or family members, availabilityof services and convenience of time schedules, increased the uptake of immunisation on thepart of mothers/caregivers. However, it also emerged that supply-side factors, such as lack of information sharing between health care providers and mothers, hindered effective communication. Additionally, inconvenient time schedules and time constraints, staffshortages, health care providers’ attitudes, inaccurate data being kept of children immunisedat other health facilities, inadequate outreach services and perceived lack of supervision in the health facilties all contributed to the low uptake of immunisation. Demand-side factors that affected the uptake of immunisation included: socio-economic constraints that led to an inability to pay transport costs to access immunisation services; lack of support from a spouse; other family members and other support structures in the community also impacted on immunisation uptake, despite the reported awareness and willingness to use immunisation services. Conclusions and recommendations: The study concludes that the relationship between health care providers and mothers/caregivers, and support from other social structures, should be good, in order to motivate mothers to use immunisation services. The study recommends that the following aspects be addressed, as they have the potential to improve the low uptake of measles immunisation: patient/provider relationship, information sharing, and supervision in the health facility, access to services, availability of outreach services, improved data tracking and active involvement of all stakeholders. Laziness was overwhelmingly offered as an explanation for missing measles immunisation, although there are suggestions that there might be underlying causes for what is perceived as laziness, which require further exploration, especially in terms of socio-cultural barriers to immunisation. It is recommended that an in-depth look at the perceptions of health care providers and key informants should be conducted to search for further understanding of contributing factors.

This thesis is concerned with quantifying the dynamical role of stochasticity in models of recurrent epidemics. Although the simulation of stochastic models can accurately capture the qualitative epidemic patterns of childhood diseases, there is still considerable discussion concerning the basic mechanisms generating these patterns. The novel aspect of this thesis is the use of analytic methods to quantify the results from simulations. All the models are formulated as continuous time Markov processes, the temporal evolutions of which is described by a master equation. This is expanded in the inverse system size, which decomposes the full stochastic dynamics into a macroscopic part, described by deterministic equations, plus a stochastic fluctuating part. The first part examines the inclusion of non-exponential latent and infectious periods into the the standard susceptible-infectious-recovered model. The method of stages is used to formulate the problem as a Markov process and thus derive a power spectrum for the stochastic oscillations. This model is used to understand the dynamics of whooping cough, which we show to be the mixture of an annual limit cycle plus resonant stochastic oscillations. This limit cycle is generated by the time-dependent external forcing, but we show that the spectrum is close to that predicted by the unforced model. It is demonstrated that adding distributed infectious periods only changes the frequency and amplitude of the stochastic oscillations---the basic mechanisms remain the same. In the final part of this thesis, the effect of seasonal forcing is studied with an analysis of the full time-dependent master equation. The comprehensive nature of this approach allows us to give a coherent picture of the dynamics which unifies past work, but which also provides a systematic method for predicting the periods of oscillations seen in measles epidemics. In the pre-vaccination regime the dynamics are dominated by a period doubling bifurcation, which leads to large biennial oscillations in the deterministic dynamics. Vaccination is shown to move the system away from the biennial limit cycle and into a region where there is an annual limit cycle and stochastic oscillations, similar to whooping cough. Finite size effects are investigated and found to be of considerable importance for measles dynamics, especially in the biennial regime.

Vaccine-preventable infectious diseases are still prevalent today. Hence, accurate data and techniques such as mathematical modelling are required to better understand their impact on a population level. This is especially the case for measles, as it has been identified to cause immune amnesia (IA): the loss of pre-existing immunological memory for other diseases after a measles infection. First, spectral analysis was used to describe the recurrent patterns of measles and whooping cough (WC) using weekly London mortality data between 1750–1900. Then, stochastic simulations of a model incorporating IA were performed to understand the effect of IA on the recurrent patterns of WC. The periodograms of the simulated model revealed that increasing IA strength and duration caused the longer periodicities of WC to resemble those of measles. This shift was seen for different population sizes, seasonal forcing amplitudes, and mean transmission rates, suggesting this trend can be observed in different ecological or social contexts. When the birth and death rates of London were used in the model with IA duration of less than a year, the WC periodogram of the simulations resembled that of the London mortality data between 1842–1900. Overall, the simulations demonstrate that IA may have contributed to the longer period spectral structure of WC that was found in the real data. Additionally, the mortality, birth rate, and death rate data presented in this thesis provide new tools for future studies in mathematical epidemiology. / Thesis / Master of Science (MSc) / This thesis presents the weekly mortality time series of measles and whooping cough between 1750 and 1900, and describes their epidemic patterns over time. We also model the phenomenon of measles-induced immune amnesia (reduced pre-existing immunity after a measles infection), and examine how it alters the recurrent patterns of whooping cough at a population level. Additionally, we construct a plausible time series of the birth and all-cause mortality rate over the same 150 years. Overall, our analysis suggests immune amnesia alters the longer periodicities of whooping cough to resemble that of measles. Furthermore, we show that this longer periodic structure is similar to that of whooping cough in the late 19th century. Finally, the given mortality, birth rate, and all-cause mortality rate time series can serve as tools for other epidemiological studies, such as predicting long-term epidemic patterns of other diseases.

No description available.

Everyone knows someone affected by cancer. It is a heterogeneous malignancy requiring different approaches depending on the source, aggressiveness, and stage of the disease. To this end, innovative cancer therapies are required to conquer the unique obstacles posed by each type of cancer. One emerging therapeutic avenue employs the use of oncolytic viruses. Oncolytic viruses are predominantly attenuated viruses that specifically replicate in cancerous cells, which often have defective anti-viral responses, while leaving normal tissue unaffected. The inability of certain cancers to counter viral infections stems from a defective interferon pathway utilized by the malignant cells for unregulated proliferation. This ingenious exploitation of the cancer’s double-edged attribute led to numerous oncolytic virus clinical trials presently culminating in an approved oncolytic virus therapy, Talimogene laherparepvec, for the treatment of advanced melanoma. Oncolytic measles virus is currently being evaluated in several pre-clinical and clinical cancer trials. This virus offers many advantages as a replicating cancer therapeutic such as an excellent safety profile, oncotropic traits, and permissiveness for enhancement via genetic engineering. Even so, further improvements of oncolytic measles virus may be required to overcome the various complexities that each type of cancer poses. Some concerns are also inherent to the use of measles virus itself, such as pre-existing neutralizing antibodies towards the virus from routine immunization. This thesis outlines three distinct projects which aim to improve oncolytic measles virus as a cancer therapeutic. Firstly, a novel pseudotyping platform for oncolytic measles virus is described as an efficient and robust system for viral envelope exchange for the purpose of evading neutralizing antibodies. Secondly, oncolytic measles virus armed with granzyme B displayed increased oncolytic and proinflammatory activity. Finally, synergizing oncolytic measles virus with viral sensitizers enhanced the replication and cancer cell killing ability of the virus in both human and murine cancer models. Each project uniquely demonstrated advances in improving oncolytic measles virus so it may surmount the current challenges facing it as a cancer therapeutic.

In many infections some patients recover while others die or are permanently disabled. These extremes in clinical outcome may be determined as much by the capacity of the host to eliminate the infecting agent as by the antigenic load on the individual. Children with measles who do not recover may succumb to acute complications (mainly respiratory) or chronic disease (respiratory and neurological) may develop. Analysis of immunological function antedating any of these final events would assist in understanding their pathogenesis and possibly aid in management. In order to achieve t h i s , immunological responsiveness was at f i r st studied in 24 children with acute measles and compared with that in 20 children with established chronic post measles chest disease investigated 6 - 1 6 weeks after appearance of the rash. The immunosuppressive effects of acute measles were extensive. Total white cells were reduced and this reduction was accounted for entirely by lymphopenia which was equally expressed among the major lymphocyte sub-populations studied; the function of T cells, assessed by radioisotope incorporation into phytohaemaggiutinin-transformed lymphocytes and by delayed skin hypersensitivity to dinitrochlorobenzene, was depressed. Serum IgA was reduced in acute measles patients. In contrast there was a relative sparing of the measured indices of immunity in patients with chronic post measles chest disease, with the major defect being an impaired delayed hypersensitivity reaction to dinitrochlorobenzene. There were minor alterations in complement components in both groups of patients with the evidence suggesting minimal utilisation of the alternative pathway in acute measles and classical pathway in chronic patients. High levels of heterophile antibodies to sheep red blood cells were detected in patients with chronic chest disease. (11) The results suggested that the conditions for chronicity of pulmonary disease in measles were unlikely to be determined by persistent abnormalities in the immunopathological factors enumerated, most of which were normal in chronic patients. It was not possible to interpret the findings of defective delayed hypersensitivity and complement components in patients with chronic chest disease as being either the cause or the effect of chronicity. The latter findings would have to be compared with results in children who had recovered from measles studied six weeks after onset of rash. An attempt was made to resolve this problem. Twenty-two children with measles were studied in the acute stage of the rash and six weeks later and results compared with matched controls. The above findings in acute measles were confirmed: the total lymphocyte count and major lymphocyte sub-populations were significantly below control values. At six weeks the B cell and Null cell counts were s t i ll significantly diminished. The function of T cells assessed by radioisotope uptake by phytohaemagglutinin-stimulated lymphocytes and by delayed skin hypersensitivity reaction to dinitrochlorobenzene was impaired during the acute stage and this persisted for six weeks. No important abnormalities were detected in serum immunoglobulins and complement components. Partial reversal of immunological suppression caused by measles was therefore demonstrated at 6 weeks after the appearance of rash. Demonstration of a persistently defective delayed hypersensitivity in those who recovered made i t unlikely that this anergy was important in the development of chronicity. Complement abnormalities were similarly unrelated to progression to chronic lung damage. ( Children who recovered, when studied at six weeks, appeared to be worse o f f immunologically than those with established chronic chest disease following measles. Children with chronic chest disease were studied 6 - 1 6 weeks after onset of rash, by which time the partial reversal of immune deficiency, noted at 6 weeks, would be complete. Among the group of children studied during the acute rash of measles there were five who subsequently died and one who progressed to chronic chest disease. Results in these six children were compared with those in six age-matched children who recovered from measles within a week. In the children who subsequently died or developed chronic pneumonia, immunosuppression was more pronounced during the acute rash ( i . e ., 3 - 2 0 days before death) than in the children who recovered. The absolute total lymphocyte count (T and B cells) was s i g n i f i c a n t ly lower in those who died or developed chronicity. Mean serum C, was also lower in this group. There were no significant differences between the two groups for total white c e l l s , neutrophils, Null c e l l s, cells with both T and B cell markers, other complement factors, serum immunoglobulins and phytohaemagglutinin stimulation of lymphocytes. The total lymphocyte count in a further nineteen patients with measles who had died, studied retrospectively, was s i g n i f i c a n t l y lower than that in twenty-seven patients with measles who recovered. Children whose outcome was poor generally had absolute lymphocyte 3 counts below 2000 cells/mm whereas those who recovered had values above this level. (iv) Therefore children who w i l l die or develop chronic chest disease can be often distinguished, within two days of the appearance of the rash, from those who w i l l recover. In order to test the v a l i d i t y of this conclusion based on results obtained from a small sample the study was extended so as to increase the number of patients with measles who had severe lymphopenia (< 2000 cells/mm3). Seventy seven per cent of 30 children who had severe lymphopenia within 2 days of appearance of rash f a i l e d to recover: 30% died from pulmonary complications within a few days to two months of the onset of the exanthem while 47% developed chronic lung damage. This was s i g n i f i c a n t ly worse than the outcome in 30 children with lymphocyte counts above 2000 3 cells/mm , of whom 67% recovered, 33% developed chronic chest disease and none died. Persistence of severe lymphopenia (which was due to reduction 3 in both T and B cells) in those with i n i t i a l counts below 2000 cells/mm , for at least fifteen days after onset of rash, remained a good predictive index of morbidity and mortality. Reversal of immunoparesis in those with i n i t i a l severe lymphopenia was slower and less complete 42 days from the appearance of the rash in children who subsequently died or progressed to chronicity than in those who recovered. All patients who died f a i l ed to produce an adequate or sustained antibody response to measles. The results of these studies suggest that long term pulmonary and possibly neurological sequelae of measles are probably due to a transient widespread immunoparesis during early measles with persistent defects in specific immunity to measles and probably other viruses, whereas recovery is due to less severe effects of shorter duration. (v) In order to answer the question why some children do badly and others well after measles, studies on the HLA frequencies and measles antigen load have been undertaken in children with severe lymphopenia. Results of viral load are inconclusive and those of HLA suggest a trend towards histocompatibility linked genetic susceptibility to the development of severe lymphopenia in measles associated with HLA AW32. The therapeutic implication of these studies is that children with measles who are at risk for death and chronic disease can be identified early in the disease and intervention at this stage may reverse the severe immunosuppression which leads to rapid demise or modify the immunopathological changes progressing relentlessly in some cases to permanent lung and brain damage and occasionally to death. / Thesis (MD)-University of Natal, Durban, 1977.

Malignant mesothelioma (MM) is an aggressive malignancy of the pleural and peritoneal surfaces. Australia has the highest reported national incidence of mesothelioma in the world, and rates are increasing (Leigh et al., 2002). The clinical outcome for patients with this disease is extremely poor, with median survival of 9 to 12 months (Rizzo et al., 2001; Carbone et al., 2002). The latest developments in chemotherapy, radiotherapy and radical surgery have done little to improve the overall survival rate (Kindler 2000; Zellos et al., 2002). New approaches to therapy are thus required (Nowak et al., 2002). Cancer therapy using conditionally replicative adenoviruses (CRAds) and attenuated measles virus (vaccine strain MV-Edm) are novel and promising approaches to cancer treatment. CRAds strategy relies on selective viral replication in tumour cells but not normal cells. Major efforts have been directed toward achieving selective replication by the deletion of viral functions dispensable in tumour cells or by the regulation of viral genes with tumour-specific promoters (Alemany et al., 2000). However, the major clinical limitation of viral therapy has been lack of efficacy rather than safety concerns. In this study, I constructed CRAds in which tumour-specific promoter for Flt-1 (vascular endothelial growth factor receptor) control the essential E1 gene expression, and evaluated the cell-killing efficacy and specificity of CRAds driven by VEGF and Flt-1 promoters in the number of established mesothelioma cell lines and actual primary tumour cells from patients. CRAds with either VEGF or flt-1 promoters showed a strong killeg effect on mesothelioma cells. Co-delivery of CRAds with MMP-9 (matrix metalloproteinase-9) was assessed to determine whether therapeutic efficacy could be improved by reducing tumourassociated fibrosis thereby enhancing viral spread through a tumour mass. Combined therapy did result in greater suppression of tumour growth in vivo. I also identified an immuno-competent murine model of mesothelioma that was permissive for adenoviral replication. Combined viral therapy with immunotherapy (FGK45, an anti-CD40 antibody) in this model resulted in greater effect than Adwt or FGK45 alone and in greatest survival. I evaluated the capacity of MV-Edm to infect human mesothelioma cells to form syncytia, and lead to apoptosis and cell death. I also assessed the mode of death by analysis of markers of apoptosis including caspase-3. In vivo study showed that MVEdm- GFP transduction could be detected in human xenografts in immune deficient mice. Further studies to evaluate the mechanisms and efficacy of anti-tumour immune stimulation induced by tumour cell killing with CRAds and MV-Edm will be discussed in this study. MV-Edm has good killing effect on mesothelioma cells in vitro. In summary the work presented herein provide new insights into stratgies to improve viral therapies for mesothelioma. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342596 / Thesis (Ph.D.) - University of Adelaide, School of Medicine, 2008

The Paramyxoviridae family includes several viruses that are important to human health, including measles virus. The envelope glycoproteins are essential for attachment and entry of the virus into the host cell [1, 2]. To develop novel therapeutics against the virus, detailed knowledge of envelope glycoprotein protein-protein interaction is important. The goal of this study is to characterize the MeV entry machinery on a molecular level. Interaction of haemaglutinin (H) and fusion (F) protein in pre-fusion form can be biochemically detected with DTSSP. To map the interaction site of H and F protein in pre-fusion form, we have mutated lysine (K) to arginine (R) in the F protein, and examined surface expression. The mutated F was still expressed on the surface and amount of surface expression correlated with fusion activity. The altered F proteins produced in this study will be used to further characterize the H-F interaction.

The development of infectious disease models remains important to provide scientists with tools to better understand disease dynamics and develop more effective control strategies. In this work we focus on the estimation of seasonally varying transmission parameters in infectious disease models from real measles case data. We formulate both discrete-time and continuous-time models and discussed the benefits and shortcomings of both types of models. Additionally, this work demonstrates the flexibility inherent in large-scale nonlinear programming techniques and the ability of these techniques to efficiently estimate transmission parameters even in very large-scale problems. This computational efficiency and flexibility opens the door for investigating many alternative model formulations and encourages use of these techniques for estimation of larger, more complex models like those with age-dependent dynamics, more complex compartment models, and spatially distributed data. How- ever, the size of these problems can become excessively large even for these powerful estimation techniques, and parallel estimation strategies must be explored. Two parallel decomposition approaches are presented that exploited scenario based de- composition and decomposition in time. These approaches show promise for certain types of estimation problems.

Routinely collected data on vaccines supplied and administered, measles notifications and hospital admissions for measles were used to evaluate the 1990 measles immunisation campaign in Natal/KwaZulu. comparisons of the monthly averages during the 12 month period before the campaign, 4 months of the campaign and 12 months after the campaign indicated that the 1990 measles campaign in Natal/KwaZulu demonstrated that the campaign was limited, not by design, to blacks only. The campaign galvanised a high degree of participation from almost all health services in this region and resulted in a rapid and marked plunge in the incidence of measles as reflected by declines in both measles notifications and measles hospital admissions. There was no deleterious shortterm residual effect of the measles campaign on routine measles immunisation services. The spillover effects of the measles campaign on routine immunisation services against polio, tuberculosis and tetanus was generally beneficial. While the campaign was a success in generating involvement of health services in Natal/KwaZulu and reducing the burden of measles in this region, this disease has not been eliminated. Vigilance and continued routine vaccination efforts are required to prevent further epidemics of measles in Natal/KwaZulu. / Thesis (M.Med.)-University of Natal, 1990.