In this thesis, we study these models and design and analyze robust numerical methods to solve them. To proceed in this direction, first we study the sub-models and then the full model. The first sub-model describes the transmission dynamics of HIV that accounts for behavior change. The impact of HIV educational campaigns is also studied. Further, we explore the effects of behavior change and different responses of individuals to educational campaigns in a situation where individuals may not react immediately to these campaigns. This is done by considering a distributed time delay in the HIV sub-model. This leads to Hopf bifurcations around the endemic equilibria of the model. These bifurcations correspond to the existence of periodic solutions that oscillate around the equilibria at given thresholds. Further, we show how the delay can result in more HIV infections causing more increase in the HIV prevalence. Part of this study is then extended to study a co-infection model of HIV-TB. A thorough bifurcation analysis is carried out for this model. Robust numerical methods are then designed and analyzed for these models. Comparative numerical results are also provided for each model.

<p>The global impact of the converging dual epidemics of tuberculosis (TB) and human immunodeficiency virus (HIV) is one of the major public health challenges of our time, because in many countries, human immunodeficiency virus (HIV) and mycobacterium tuberculosis (TB) are among the leading causes of morbidity and mortality. It is found that infection with HIV increases the risk of reactivating latent TB infection, and HIV-infected individuals who acquire new TB infections have high rates of disease progression. Research has shown that these two diseases are enormous public health burden, and unfortunately, not much has been done in terms of modeling the dynamics of HIV-TB co-infection at a population level. In this thesis, we study these models and design and analyze robust numerical methods to solve them. To proceed in this direction, first we study the sub-models and then the full model. The first sub-model describes the transmission dynamics of HIV that accounts for behavior change. The impact of HIV educational campaigns is also studied. Further, we explore the effects of behavior change and different responses of individuals to educational campaigns in a situation where individuals may not react immediately to these campaigns. This is done by considering a distributed time delay in the HIV sub-model. This leads to Hopf bifurcations around the endemic equilibria of the model. These bifurcations correspond to the existence of periodic solutions that oscillate around the equilibria at given thresholds. Further, we show how the delay can result in more HIV infections causing more increase in the HIV prevalence. Part of this study is then extended to study a co-infection model of HIV-TB. A thorough bifurcation analysis is carried out for this model. Robust numerical methods are then designed and analyzed for these models.&nbsp / Comparative numerical results are also provided for each model.</p>

The last few years have seen an increase in the infection rate not only of HIV but also TB. The HIV/AIDS pandemic is increasing rapidly mainly in developing countries with 71 % of infections in the Sub-Saharan region of Africa. South Africa, which forms part of the Sub- Saharan region, has the highest infection rate in the world with 3.2 to 3.4 million people living with HIV/AIDS. People with HIV are especially vulnerable to TB, and HIV pandemic is fuelling an explosive growth in TB cases. The increase in the infection rate of TB and HIV exert increased pressure on health service delivery thus reflecting the serious problem in the country with regard to health service delivery to people co-infected with TB and HlV/AlDS. Health service delivery is also hindered by negative attitudes of health workers that have been reported towards people living with HIV/AIDS. They entertain a biased view of their own risk, considering risk only from occupational exposure and denying the possibility of infection in their private life. These attitudes of health workers decreases the quality of care and support delivered to patient co-infected with TB and HIV. This result in people not disclosing their illness even in cases were treatment is available like TB for the fear of stigmatisation. Hence the problem of stigmatisation escalates into a dilemma for the patient co-infected with TB and HIV. Therefore these patients tend to shy away from health services and isolate themselves due to fear of being stigmatised twice. The need to address TB and HIV together in the light of this dimension is urgent so as to improve the utilization of the health services by people co-infected with Ti3 and HIV. The purpose of this research was to explore and describe the experiences of patients co-infected with TB and HIV regarding stigmatisation by the health workers, to explore and describe the attitudes of health workers towards patients co-infected with TB and HIV, and to formulate guidelines for health workers that will facilitate the health service utilization by patients co-infected with TB and HIV in the Potchefstroom district. The research was conducted in the Potchefstroom district in the North West province of South Africa. A qualitative research design was used to explore and describe the experiences of patients co-infected with TB and HIV regarding stigmatisation by the health workers, and to explore and describe the attitudes of health workers toward co-infected patients. A purposive voluntary sampling method was used to select participants who met the set criteria. Two populations were used, that is the patients co-infected with TB and HIV, and the health workers who were involved in their care. In depth unstructured interviews were conducted with the patient population and semi structured interviews with the health worker population using an interview schedule that was formulated from the background literature. Data was captured on an audiotape, and transcribed verbatim. Field notes were taken immediately after each interview. The researcher and a co-coder did data analysis after data saturation was reached and a consensus was reached on the categories that emerged. From the findings of this research it appeared that there were general perceptions by the patients co-infected with TB and HIV that indicated stigmatisation by the health workers. This perceived stigmatisation was reported as being perpetrated by all categories of health workers. Negative behaviours such as the health workers not having time for the patients and being impatient were reported. Lack of sufficient knowledge was related to these behaviours especially amongst lower categories or non-professional health workers. In spite of the above, the researcher also observed that there was a limited number of health workers who were still being perceived as committed and caring by the patients co-infected with TB and HIV. The researcher concluded that the relationship between the health workers and the patients co-infected with TB and HIV was characterised by conflict. The health workers seemed to perceive the patients co-infected with TB and HIV as stubborn, harsh, abuse alcohol, manipulative and not taking responsibility of their illness. These perceptions lead the health workers to have a negative attitude towards these patients and occasionally came across as unsympathetic towards them. On the other hand the researcher observed that there were other health workers who did not present with negative behaviours towards these patients and tried to understand the reasons for their sometimes-unacceptable behaviours. Recommendations are made for the field of nursing education, community health nursing practice and nursing research with the formulation of guidelines for health workers so as to facilitate the utilization of the health services by the patients co-infected with TB and HIV. The guidelines are discussed under three main categories, namely guidelines for the health workers to facilitate the utilization of the health services by the patients co-infected with TB and HIV, guidelines to improve the utilization of the health services more efficiently and adequately by the patients co-infected with TB and HIV, and guidelines to improve the attitudes of the health workers towards the patients co-infected with TB and HIV with the intention of improving the utilization of the health services by these patients. / Thesis (M.Cur.)--North-West University, Potchefstroom Campus, 2006.

<p><font face="Times New Roman" size="3"><font face="Times New Roman" size="3"> <p align="left">The aim of the study is to explore the barriers associated with low VCT uptake by the TB patients attending primary health care clinics within the Buffalo City municipality. <font face="Times New Roman" size="3"><font face="Times New Roman" size="3">The study population was drawn from TB patients attending the primary health care facilities in Buffalo city municipality in the Eastern Cape Province. Eight participants were purposively selected to include those who had accepted VCT as well as those who did not.</font></font></p> </font></font></p>

<p>The global impact of the converging dual epidemics of tuberculosis (TB) and human immunodeficiency virus (HIV) is one of the major public health challenges of our time, because in many countries, human immunodeficiency virus (HIV) and mycobacterium tuberculosis (TB) are among the leading causes of morbidity and mortality. It is found that infection with HIV increases the risk of reactivating latent TB infection, and HIV-infected individuals who acquire new TB infections have high rates of disease progression. Research has shown that these two diseases are enormous public health burden, and unfortunately, not much has been done in terms of modeling the dynamics of HIV-TB co-infection at a population level. In this thesis, we study these models and design and analyze robust numerical methods to solve them. To proceed in this direction, first we study the sub-models and then the full model. The first sub-model describes the transmission dynamics of HIV that accounts for behavior change. The impact of HIV educational campaigns is also studied. Further, we explore the effects of behavior change and different responses of individuals to educational campaigns in a situation where individuals may not react immediately to these campaigns. This is done by considering a distributed time delay in the HIV sub-model. This leads to Hopf bifurcations around the endemic equilibria of the model. These bifurcations correspond to the existence of periodic solutions that oscillate around the equilibria at given thresholds. Further, we show how the delay can result in more HIV infections causing more increase in the HIV prevalence. Part of this study is then extended to study a co-infection model of HIV-TB. A thorough bifurcation analysis is carried out for this model. Robust numerical methods are then designed and analyzed for these models.&nbsp / Comparative numerical results are also provided for each model.</p>

There is a growing interest in the dynamics of the co-infection of these two diseases. In this thesis, firstly we focus on studying the effect of a distributed delay representing the incubation period for the malaria parasite in the mosquito vector to possibly reduce the initial transmission and prevalence of malaria. This model can be regarded as a generalization of SEI models (with a class for the latently infected mosquitoes) and SI models with a discrete delay for the incubation period in mosquitoes. We study the possibility of occurrence of backward bifurcation. We then extend these ideas to study a full model of HIV and malaria co-infection. To get further inside into the dynamics of the model, we use the geometric singular perturbation theory to couple the fast and slow models from the full model. Finally, since the governing models are very complex, they cannot be solved analytically and hence we develop and analyze a special class of numerical methods to solve them.

In this thesis, we study these models and design and analyze robust numerical methods to solve them. To proceed in this direction, first we study the sub-models and then the full model. The first sub-model describes the transmission dynamics of HIV that accounts for behavior change. The impact of HIV educational campaigns is also studied. Further, we explore the effects of behavior change and different responses of individuals to educational campaigns in a situation where individuals may not react immediately to these campaigns. This is done by considering a distributed time delay in the HIV sub-model. This leads to Hopf bifurcations around the endemic equilibria of the model. These bifurcations correspond to the existence of periodic solutions that oscillate around the equilibria at given thresholds. Further, we show how the delay can result in more HIV infections causing more increase in the HIV prevalence. Part of this study is then extended to study a co-infection model of HIV-TB. A thorough bifurcation analysis is carried out for this model. Robust numerical methods are then designed and analyzed for these models. Comparative numerical results are also provided for each model.

Influenza virus is one of the major respiratory pathogens of humans as well as animals, including equines. There is an increasing evidence that bacterial infections are the most common cause of the death during influenza. In horses also, secondary bacterial pneumonia can lead to death, and surviving horses may take up to six months for the complete recovery resulting in heavy economic loss to the equine industry. Interleukin (IL)-23 mediated innate immune response has been shown to protect the host from various respiratory bacterial infections. However, studies to investigate the role of host and viral factors in the regulation of IL-23 are limited. Endoplasmic reticulum (ER) stress-induced transcription factor CHOP-10 and IFN-β has been shown to participate in the regulation of IL-23. Primary hypothesis for the current study was that influenza A virus (IAV) NS1 protein downregulates the IL-23 expression via inhibition of CHOP-10. In order to test our hypothesis, we infected the RAW264.7 cells - a murine macrophage cell line, and primary murine alveolar macrophage cells either with the wild type Influenza A virus (PR/8/34, PR8) or isogenic mutant virus lacking NS1 (delNS1). Quantitative analysis of mRNA expression revealed a significantly higher mRNA expression of IL23p19, IFN-β and CHOP-10 in delNS1 virus infected cells as compared the PR8 virus infected cells. Additionally, overexpression of CHOP-10 partially restored the expression of IL-23p19 in PR8 virus infected cells and knockdown of CHOP-10 resulted in downregulated expression of IL-23p19 in delNS1 infected cells. Taken together, these results suggest that IAV NS1 protein mediated inhibition of CHOP-10 expression leads to downregulation of IL-23 expression in macrophage cells in-vitro. Similar results were also observed in-vivo using IAV and Streptococcus zoooepidemicus (S. ze) co-infection model. In a co-infection mouse model delNS1 virus co-infection resulted in significantly higher expression of the IL-23 and IL-17. Considering the role of IL-23 in protection against respiratory bacterial pathogens, effect of exogenous supplementation of IL-23 was also investigated in the influenza and S. ze co-infection mouse model. We found that a single intranasal dose of recombinant murine IL-23 significantly improved the survival of mice co-infected with PR8 and S .ze. Overall, our study suggests that IAV infection subverts the IL-23 mediated respiratory innate immune response and restoration of IL-23 could protect from influenza-associated respiratory bacterial infections.

The last few years have seen an increase in the infection rate not only of HIV but also TB. The HIV/AIDS pandemic is increasing rapidly mainly in developing countries with 71 % of infections in the Sub-Saharan region of Africa. South Africa, which forms part of the Sub- Saharan region, has the highest infection rate in the world with 3.2 to 3.4 million people living with HIV/AIDS. People with HIV are especially vulnerable to TB, and HIV pandemic is fuelling an explosive growth in TB cases. The increase in the infection rate of TB and HIV exert increased pressure on health service delivery thus reflecting the serious problem in the country with regard to health service delivery to people co-infected with TB and HlV/AlDS. Health service delivery is also hindered by negative attitudes of health workers that have been reported towards people living with HIV/AIDS. They entertain a biased view of their own risk, considering risk only from occupational exposure and denying the possibility of infection in their private life. These attitudes of health workers decreases the quality of care and support delivered to patient co-infected with TB and HIV. This result in people not disclosing their illness even in cases were treatment is available like TB for the fear of stigmatisation. Hence the problem of stigmatisation escalates into a dilemma for the patient co-infected with TB and HIV. Therefore these patients tend to shy away from health services and isolate themselves due to fear of being stigmatised twice. The need to address TB and HIV together in the light of this dimension is urgent so as to improve the utilization of the health services by people co-infected with Ti3 and HIV. The purpose of this research was to explore and describe the experiences of patients co-infected with TB and HIV regarding stigmatisation by the health workers, to explore and describe the attitudes of health workers towards patients co-infected with TB and HIV, and to formulate guidelines for health workers that will facilitate the health service utilization by patients co-infected with TB and HIV in the Potchefstroom district. The research was conducted in the Potchefstroom district in the North West province of South Africa. A qualitative research design was used to explore and describe the experiences of patients co-infected with TB and HIV regarding stigmatisation by the health workers, and to explore and describe the attitudes of health workers toward co-infected patients. A purposive voluntary sampling method was used to select participants who met the set criteria. Two populations were used, that is the patients co-infected with TB and HIV, and the health workers who were involved in their care. In depth unstructured interviews were conducted with the patient population and semi structured interviews with the health worker population using an interview schedule that was formulated from the background literature. Data was captured on an audiotape, and transcribed verbatim. Field notes were taken immediately after each interview. The researcher and a co-coder did data analysis after data saturation was reached and a consensus was reached on the categories that emerged. From the findings of this research it appeared that there were general perceptions by the patients co-infected with TB and HIV that indicated stigmatisation by the health workers. This perceived stigmatisation was reported as being perpetrated by all categories of health workers. Negative behaviours such as the health workers not having time for the patients and being impatient were reported. Lack of sufficient knowledge was related to these behaviours especially amongst lower categories or non-professional health workers. In spite of the above, the researcher also observed that there was a limited number of health workers who were still being perceived as committed and caring by the patients co-infected with TB and HIV. The researcher concluded that the relationship between the health workers and the patients co-infected with TB and HIV was characterised by conflict. The health workers seemed to perceive the patients co-infected with TB and HIV as stubborn, harsh, abuse alcohol, manipulative and not taking responsibility of their illness. These perceptions lead the health workers to have a negative attitude towards these patients and occasionally came across as unsympathetic towards them. On the other hand the researcher observed that there were other health workers who did not present with negative behaviours towards these patients and tried to understand the reasons for their sometimes-unacceptable behaviours. Recommendations are made for the field of nursing education, community health nursing practice and nursing research with the formulation of guidelines for health workers so as to facilitate the utilization of the health services by the patients co-infected with TB and HIV. The guidelines are discussed under three main categories, namely guidelines for the health workers to facilitate the utilization of the health services by the patients co-infected with TB and HIV, guidelines to improve the utilization of the health services more efficiently and adequately by the patients co-infected with TB and HIV, and guidelines to improve the attitudes of the health workers towards the patients co-infected with TB and HIV with the intention of improving the utilization of the health services by these patients. / Thesis (M.Cur.)--North-West University, Potchefstroom Campus, 2006.

Estudos preliminares visando a identificação de possíveis agentes virais associados à síndrome multissistêmica do definhamento dos suínos (SMDS) revelaram uma possível associação inversa entre a presença de TTSuV1 e a ocorrência da SMDS. Com base neste achado, foi formulada a hipótese de que o TTSuV1 poderia ser capaz de inibir a multiplicação do PCV2, impedindo assim o desenvolvimento da SMDS. Buscando esclarecer esta questão, seria necessário desenvolver um sistema eficiente de replicação para este vírus, até o presente ainda não disponível. Em vista disso, foi desenvolvido um método de detecção de infecções por TTSuV em cultivos celulares para a avaliação de possíveis linhagens a serem potencialmente utilizadas para isolamento e multiplicação destes vírus. Genomas de TTSuVs foram detectados em células de linhagem de origem suína e não suína assim como em um dos lotes de tripsina. Os soros utilizados como suplemento para o meio de cultivo não apresentaram genomas de TTSuV. Desta forma, o lote de tripsina contaminado pode ser considerado uma importante fonte de contaminação, principalmente em células de origem não suína. Com o objetivo de avaliar uma possível associação entre os TTSuVs e a ocorrência da SMDS, a frequência de detecção e quantificação de genomas de TTSuV1 e TTSuV2 em tecidos e soros de suínos com e sem SMDS foram determinadas. A análise feita nos diferentes tecidos de suínos revelou uma aparente correlação inversa entre a presença do genoma de TTSuV1 e a ocorrência da SMDS. Quanto ao TTSuV2 em tecidos de suínos com e sem a SMDS, nenhuma diferença estatística foi observada. A distribuição do genoma de TTSuV1 e TTSuV2 nos diferentes tecidos examinados não revelou um órgão alvo específico. A frequência de detecção e a carga viral de TTSuV1 e 2 nas amostras de soro de suínos com e sem a SMDS não apresentaram diferença significativa. No entanto, a carga viral de TTSuV2 foi mais alta do que a carga viral de TTSuV1 nos soros de todos os grupos de animais estudados. Estes resultados indicam uma alta frequência de detecção de ambas as espécies de TTSuV em amostras de tecidos e soros de suínos com e sem a SMDS. / Preliminary studies aiming the identification of possible viral agents associated with the postweaning multisystemic wasting syndrome (PMWS) revealed a possible negative association between TTSuV1 and occurrence of PMWS. Based on this finding was hypothesized that TTSuV1 might be able to inhibit the PCV2 multiplication, preventing the development of PMWS. To better clarify this, would be require an efficient system of replication for this virus, which has not been reported in the literature. In view of this, a method for detection of TTSuV infections in cell culture was developed to assess possible cell lineages to be potentially used for virus isolation and multiplication. TTSuV genomes were detected in cell lineages of porcine and nonporcine origin as well as a batch of trypsin. Sera used as media supplement was not found to contain TTSuV genomes. Thus, the contaminated batch of trypsin can be considered an important source of contamination, especially in cells of non-porcine origin. In order to evaluate a possible association between the TTSuVs and the occurrence of PMWS, the frequency of detection and quantification of TTSuV1 and TTSuV2 genomes in tissues and sera from pigs with and without PMWS were determined. The analysis in the different tissues of pigs reveal an apparent inverse correlation between the frequency of detection of TTSuV1 genomes and the occurrence of PMWS. Regarding TTSuV2 in tissues of PMWS and non-PMWS-affected animals no significant differences was observed. The distribution of TTSuV1 and TTSuV2 genomes in tissues did not reveal any particular target organ. The frequency of detection and viral load of TTSuV1 and TTSuV2 in sera samples were no significant statistically among animals PMWS-affected and healthy pig. The mean of TTSuV2 viral load was significantly highest than TTSuV1 in sera of all groups studied. These results indicate a high frequency of detection of both TTSuV species in tissues and sera samples from PMWS-affected and healthy pig.