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• 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.
1

#### Coinfection and the Evolution of Resistance: A Mathematical Analysis

HANSEN, Johanna 06 May 2011 (has links)
This thesis investigates the effect of coinfection on the emergence of resistant pathogens. Firstly, a multiple infection model with treatment is derived and the conditions for invasion are established. The invasion condition is then related to an equivalent and easier to obtain condition, R0, by applying the Next-Generation Theorem. Due to its biological interpretation, a heuristic derivation of R0 as the invasion condition is also given. Then assuming that resistance comes at a cost to the pathogen, and using a very simple within-host model, we establish under which specific set of biological assumptions we should expect coinfection to increase or decrease R0. Specifically, we obtain that in the no cost of resistance case, reduced transmission case, and increased mortality case, that coinfection will increase the R0 value and that in the reduced growth and poor competitor case that the effect is indeterminate. We also introduced a method for approximating the intrinsic growth rate when the coinfection efficiency is assumed to be small. Using this method, we show that we obtain the same trend for the cost of resistance cases when comparing our estimate for the intrinsic growth rate for the coinfection case versus the intrinsic growth rate for the single infection case. We also use this approximation to estimate the percentage of resistance as a function of time. Finally, we analyze how both the intrinsic growth rate and R0 respond to a changing treatment rate, compared to the intrinsic growth rate and R0 value in the single infection case. We found that the change in R0 and the intrinsic growth rate can be greater or smaller than the change in R0 or the intrinsic growth rate for the single infection case. / Thesis (Master, Mathematics & Statistics) -- Queen's University, 2011-05-05 16:36:40.865
2

#### Interaction between chikungunya and dengue viruses during co-infection in Aedes mosquito cells and in Aedes aegypti mosquito / Interférence entre les virus Chikungunya et Dengue pour l'utilisation de voies cellulaires communes chez les insectes vecteurs lors de co-infection

Enguehard, Margot 11 September 2017 (has links)
Au cours des dernières années, de nombreuses épidémies ont emergé ou ré émergé, et sont causées par des arbovirus (arthropod-borne viruses), des virus transmis à des vertébrés par des insectes piqueurs vecteurs. Avec l'augmentation de la densité humaine dans certaines zones géographiques et le réchauffement climatique qui contribuent à l'expansion géographique des vecteurs, les maladies induites par ces virus (arboviroses) ont un impact de plus en plus important sur la santé humaine et l'économie mondiale. Il est donc déterminant d'augmenter nos connaissances sur les systèmes mis en jeux pour garantir la sécurité sanitaire des populations exposées. Les enjeux actuels reposent aussi bien sur la compréhension des virus que sur la compréhension de l'alternance d'hôtes, directement responsables de l'émergence et la dissémination des agents infectieux. Les moustiques sont des vecteurs majeurs des arbovirus comme la dengue (genre Flavivirus) et le Chikungunya (genre Alphavirus). Transmis par les mêmes moustiques Aedes aegypti et Aedes albopictus, le virus de la Dengue (DENV) est responsable de la plus importante arbovirose en zone tropicale, et le virus Chikungunya (CHIKV) est responsable dans le monde entier de centaines de milliers de cas d'infection, et les épidémies récentes ont touché les pays européens. Ainsi, il a été observé que le moustique Ae. albopictus pouvait porter simultanément CHIKV et DENV, et des cas de co-infections humaines ont été observés en Afrique. Toutefois, bien qu'en théorie les deux virus soient capables d'infecter les mêmes cellules chez l'insecte ou l'homme, il n'y a aucune étude détaillée sur les interactions au niveau cellulaire entre CHIKV et DENV lors de la co-infection d'une cellule. C'est pourquoi il est indispensable d'accroitre nos connaissances sur l'interférence éventuelle entre les virus Chikungunya et Dengue pour l'utilisation de voies cellulaires communes chez les insectes vecteurs et l'hôte humain lors de co-infection / Emergence and geographical extension of dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses increase simultaneous outbreak in an increasing number of countries. To date, no vaccine or cure have yet been developed against these diseases those cause a tremendous impact on human health and in the economy worldwide. During recent simultaneous outbreaks, up to 12% of patients have been diagnosed to be co-infected by CHIKV and DENV. In addition, it was shown that the mosquitoes Aedes albopictus could carry and transmit simultaneously CHIKV and DENV. However, the pathology, as well as the epidemiology of a pathogen, relies on the interactions between several infectious agents present within an organism or a community in the environment. It is crucial to consider to which extent a host infected by a first microorganism is modified and whether its reaction to the infection by a second microorganism is consequently altered. However, there is no extensive report of Alphavirus-Flavivirus or Flavivirus- Flavivirus interactions. Our global objective is to characterize these co-infections in both mosquitoes and humans, at the cell and molecular level. To this aim, we started this project by performing sequential co- infection in different cell lines from Aedes albopictus and Aedes aegypti. We found that the permissiveness and production of DENV is enhanced in presence of CHIKV. On the contrary, there is no effect of DENV pre-infection on subsequent CHIKV co-infection. We generalized the synergistic phenomena and we showed that CHIKV pre-infection also increased the infection by DENV-1, DENV-3 and DENV-4, but also by two others re-emerging Flaviviruses, the Yellow Fever Virus (YFV), and the Zika Virus (ZIKV). Remarkably, we succeeded to establish a mosquito model of co-infection of Aedes aegypti mosquito after by different two feedings at 4 days interval. Using this sequential co-infection, we were able to show that a pre-infection of Aedes aegypti by CHIKV increase the level of DENV-2 RNA in salivary glands compare to mono-infected mosquitos. This phenotype is reminiscent of the phenotype we observed in vitro during successive infections. Altogether, our study paves the way to the characterization of molecular interaction between Flaviviruses and Alphaviruses in mosquito in vitro and in vivo. This study can be crucial for a better understanding of disease and epidemiology during simultaneous outbreaks
3

#### Coinfección por dengue y leptospirosis en una niña de la Amazonía Peruana

Núñez Garbín, Alexandra, Espinoza Figueroa, Jossué, Sihuincha Maldonado, Moisés, Suárez Ognio, Luis 07 April 2015 (has links)
We report the case of a 10 year old girl, born and raised in the city of Iquitos in Peru who presented with headache, fever, chills, musculoskeletal pain, mild epigastric pain, epistaxis and hematemesis. On physical examination, the patient was afebrile and in good general condition. Serological tests confirmed infection of dengue and leptospirosis. The patient received intravenous hydration with sodium chloride 0.9% and penicillin G sodium, achieving a favorable clinical course such that she was discharged a few days after admission to the hospital. Although these diseases are common in the Peruvian Amazon, the simultaneous presence of both in the pediatric population is little documented; therefore, a good clinical history and laboratory tests are important for diagnosis and treatment. / alexandrang@gmail.com / Se reporta el caso de una niña de 10 años, natural y procedente de la ciudad de Iquitos en Perú que presentó cefalea, fiebre, escalofríos, dolor osteomuscular, leve dolor en epigastrio, epistaxis y hematemesis. Al examen físico la paciente se encontraba afebril y en regular estado general. Por medio de pruebas serológicas se confirmó la infección por dengue y leptospirosis. La paciente recibió hidratación endovenosa con cloruro de sodio al 0,9% y penicilina G sódica, logrando una evolución clínica favorable por lo que fue dada de alta a los pocos días de su ingreso al hospital. Aunque estas dos enfermedades son comunes en la Amazonía peruana, la presencia simultánea de ambas en la población pediátrica es poco documentada; por ello, una buena historia clínica y exámenes de laboratorio son importantes para el diagnóstico y tratamiento oportuno.
4

#### Epidemiology and clinical outcomes associated with Theileria parva in a cohort of East African short horn zebu calves

Jennings, Amy Elizabeth January 2013 (has links)
This thesis takes data from the Infectious Diseases of East African Livestock (IDEAL) project. The project was a longitudinal calf cohort study based in Western Kenya. Indigenous short horn zebu calves were recruited at birth and then visited every 5 weeks through their first year of life. The aim of this thesis was to improve understanding of the epidemiology of Theileria parva, with a particular focus on variation in host response. 362 of the 548 calves in the study cohort were classified as having seroconverted to T. parva, and 381 to T. mutans before 1 year old. The diagnostic tools used to identify exposure in the calf were compared, and environmental and calf level risk factors associated with the age at seroconversion were sought. Decreased elevation of the homestead and increased size of the herd were found to be significantly associated with an increased hazard of seroconversion to T. parva. There was little variation in hazard of T. mutans captured across the study site. The outcome ‘clinical episode’ was used to classify whether the calf was ill at each routine visit. A large number of calves passed through their first year of life without clinical disease being observed, and a minority of calves experienced the majority of clinical episodes. Multiple clinical episodes were apparently related in time, suggesting that they were due either to the same or connected pathogenic processes. A low birth weight, larger herds, and older farmers were all risk factors for being a sick calf. Both high helminth burden and T. parva were found to be significantly associated with clinical disease at a population level. A lot of variation was seen in the clinical presentation of disease. The clinical signs associated with fatal East Coast Fever (ECF), the clinical disease associated with T. parva infection, were found to be very variable. Although this may have been partly due to the varying times in the disease process that calves were observed prior to death, the complication of the clinical picture was also suggested to be due to co-infections. 71% of the cohort was infected with T. parva in their first year of life, but only a fraction (8.7%) went on to die from that infection. Unmatched and matched nested case control study formats were used to investigate the risk factors associated with death following T. parva infection (ECF death) in these calves. It was found that being infected young was a risk factor for death. Calves owned by older farmers were also at higher risk of death following infection. Going out grazing was found to be protective, and equivocal evidence was found for an association between prior T. mutans exposure and reduced odds of ECF death. If these initial findings from this work are correct, it is likely that T. mutans is influencing the clinical presentation of T. parva in endemic regions.
5

#### Óbitos entre pacientes com tuberculose no município de Campinas, 2001 a 2009 / Deaths among tuberculosis patients in the municipality of Campinas, between 2001 and 2009

Saita, Nânci Michele, 1984- 20 August 2018 (has links)
6

#### Social behaviour in bacteria : regulation, coinfection, and virulence

Cornforth, Daniel Michael January 2014 (has links)
Bacteria interact with one another in many ways, through helpful behaviours like producing fitness-enhancing secretions and signals as well as harmful ones like the release of anti-competitor toxins. These interactions are essential for bacterial growth and survival and can have substantial impacts on the virulence of bacterial pathogens. This thesis explores the theory of social interactions among bacteria, focusing on both the mechanisms that underlie them as well the consequences for pathogens coinfecting a host. I first propose a hypothesis for the regulation of competitive traits in bacteria. By analysing published literature on anti-competitor toxin regulation I suggest that one of the principal mediators of antagonistic behaviour in bacteria is sensing harm from competitors. In particular, I argue that certain types of stress responses, known to protect bacteria from environmental assault, are fundamental in allowing bacteria to sense competitive threats. Next I focus on another mechanism of sensing social partners, quorum sensing, which has been argued alternatively to either sense bacterial cell density or the mass transfer properties of an environment. I propose a hypothesis on how the use of multiple quorum sensing signals molecules, a common feature across many bacteria, can potentially help resolve ambiguity between social and physical aspects of a cell’s environment. The rest of the thesis focuses on the epidemiology of coinfection, bacterial and otherwise. In some parasites, high coinfection rates lead to an increased level of evolved virulence due to competition between lineages inside the host. In contrast, when cooperative secretions contribute to virulence, the opposite can occur because high producing virulent strains are out-competed by parasites that do not produce public goods. I develop a mathematical model to show that the structure of parasites inside the host largely determines the fate of virulence when there is social interaction at a local level within the host. This analysis shows that multiplicity of infection can have either a positive or negative effect on virulence depending on structuring within the host. Lastly I explore how host contact structure influences coinfection rates and show that when hosts have very heterogeneous numbers of contacts, a small fraction of individuals in the population has a disproportionate effect on coinfection, which in turn shapes pathogen evolution.
7

#### PrevalÃncia e fatores de risco associados Ã coinfecÃÃo com vÃrus da hepatite B (HBV) em pacientes HIV positivos no estado do PiauÃ. / Prevalence and risk factors associated with coinfection with hepatitis B virus (HBV) in HIV-positive patients in the state of PiauÃ.

Ana LuÃsa EulÃlio Dantas AragÃo 07 October 2011 (has links)
nÃo hÃ / A coinfecÃÃo entre o VÃrus da ImunodeficiÃncia Humana (HIV) e o VÃrus da Hepatite B (HBV) possui os mesmos fatores de transmissÃo e como consequÃncia os fatores de risco associados, explicam a alta prevalÃncia destes agentes infecciosos no nosso meio. O presente estudo estimou a prevalÃncia da coinfecÃÃo HIV e HBV e descreveu as caracterÃsticas individuais que agem como fatores de risco para aquisiÃÃo desta coinfecÃÃo, com o intuito de utilizar esta informaÃÃo para o aconselhamento. A amostra utilizada foi composta pelos 805 pacientes infectados com o HIV no estado do PiauÃ que buscaram o LACEN-PI para monitoramento da carga viral e dos linfÃcitos T CD4+. A prevalÃncia da hepatite B (HB), utilizando o marcador anti-HBc total, foi de 29,3% e, para o HBsAg este valor ficou em 2,5%. A prevalÃncia do Anti-HBc total foi 38,3% na faixa acima dos 40 anos, 38,6% para o sexo masculino, 31,9% entre os solteiros, 47,7% entre os aposentados, 50,7% entre os que relataram antecedente de icterÃcia, 54% entre os que tiveram hepatite com diagnÃstico mÃdico, 40,7% entre os com passagem por reformatÃrio ou prisÃo, 38,1% entre usuÃrios de droga nÃo endovenosa, 35,7% entre os com contato sexual com usuÃrio de droga ilÃcita, 48,8% entre os com preferÃncia homossexual/bissexual, 44,9% entre os que disseram ter contato sexual raro com prostituta, 37,1% entre os que tiveram DST e 31,4% para os com carga viral abaixo de 10.000 cÃpias/mL de sangue. Foram observadas significÃncias estatÃsticas entre as variÃveis e a frequÃncia de positividade do anti-HBc total. As informaÃÃes deste trabalho poderÃo ser utilizadas no combate, aconselhamento e prevenÃÃo do avanÃo, do nÃmero de casos HB em pacientes HIV positivos. / The coinfection between the Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV) has the same transmission factors and consequently the associated risk factors explain the high prevalence of these infectious agents in our midst. This study estimated the prevalence of HIV and HBV coinfection and described the individual characteristics that act as risk factors for acquisition of coinfection, in order to use this information for advice. The sample was composed of 805 patients infected with HIV in the state of PiauÃ who sought the LACEN-PI for monitoring viral load and CD4 + T lymphocytes. The prevalence of Hepatitis B (HB), using the marker anti-HBc, and was 29.3% for HBsAg this value was 2.5%. The prevalence of Anti-HBc was 38.3% aged over 40 years, 38.6% for males, 31.9% among unmarried, 47.7% among retirees, 50.7% among who reported a history of jaundice, 54% among those who were diagnosed with hepatitis, 40.7% among those passing through reformatory or prison, 38.1% among non-intravenous drug users, 35.7% with sexual contact with illicit drug users, 48.8% with a preference among homosexual / bisexual, 44.9% among those who reported having sexual contact with a prostitute rare, 37.1% among those who had STD and 31.4% for those with viral load below 10,000 copies / mL of blood. We observed statistical significance between variables and the frequency of positive anti-HBc. The information in this work could be used in combat, counseling and prevention of advancement, the number of HB cases in HIV positive patients.
8

#### Evaluation of rotavirus models with coinfection and vaccination

Ortega, Omayra Y 01 January 2008 (has links)
Rotavirus diarrhea causes a disproportionate amount of the world's childhood mortality. Approximately 611,000 children die each year due to complications of rotavirus infections. In this study we evaluate rotavirus vaccination using four different methods. We look at the epidemiological history of the disease and vaccination against the disease, then we evaluate the effectiveness of vaccination first using a cost-benefit analysis, then using an ordinary differential equations based model, and last through computer simulations in Matlab. We do a traditional cost-benefit analysis as suggested by the Public Health Service of the United States to evaluate the costs and benefits of implementing a rotavirus vaccination program in Egypt with the RotaRix vaccine. Our results show that given the current standards of care in Egypt, it would be more cost-beneficial for Egypt not to use the rotavirus vaccine. We formulate a model of the spread of rotavirus diarrhea based on a continuous time ordinary differential equations model of two viral strains of influenza. We expand this influenza model to include the case of co-infection. We further expand the original model to explore the effects of vaccination. We used computer simulations to further analyze the effect of vaccination as a control method. These simulations show that the spread of the disease is highly sensitive to the levels of cross-immunity between the strains, and the level of vaccination in the population. We found that the dynamics observed in the new model are similar to the dynamics observed in the original model. We found the minimum levels of vaccination necessary in this model to eradicate severe rotavirus disease and minimum levels of cross-immunity between the strains
9

#### Le rôle de l’immunité à médiation cellulaire dans le syndrome inflammatoire de reconstitution immunitaire chez les patients co-infectés VIH/TB sous traitement antituberculeux et antirétroviraux au Cambodge / Role of cellular immunity in Immune Reconstitution Inflammatory Syndrome (IRIS) in patient co infected HIV/TB under treatment of anti tuberculosis and antiretroviral in Cambodia

Pean, Polidy 06 December 2011 (has links)
Syndrome inflammatoire lié à la reconstitution immunitaire chez le patient coinfecté par le VIH et la tuberculose est une complication du traitement par des antirétroviraux, appelé TB-IRIS. Ce syndrome est souvent rencontré dans les pays en voie de développement. Son diagnostic se pose essentiellement sur la présentation clinique et nécessiter de se différentier des autres pathologies. Son évolution est souvent favorable ou sous corticoïde mais certaine forme est sévère et/ou mortelle. L'étude de leur mécanisme permettra d'identifier de marqueur prédictif, applicable à leur diagnostic précoce et à l'amélioration de leur prise en charge. Alors, nous avons proposés d'étudier le rôle de cellule NK et le rôle de lymphocyte T dans l'essai clinique de CAMELIA au Cambodge. Le résultat a montré l'élévation de la capacité de dégranulation de cellule NK est associé à la survenu de TB-IRIS et il peut être un marqueur prédictif. De plus, l'hyperactivation de cellule T effectrice et la diminution de cellule T régulatrice sont aussi observées. Le rôle de cellule T régulatrice n'est pas encore préciser. Le mécanisme régulateur de ce phénomène doit être ultérieurement exploré. / Inflammatory syndrome associated with immune reconstitution in patients coinfected with HIV and TB is one complication of antiretroviral treatment, called TB-IRIS. This syndrome more often encountered in developing countries. Diagnosis of this syndrome is mainly based of clinical presentation and needs to differentiate from other diseases. Their evolution is usually favorable or under corticosteroids, but some cases are severe and / or fatal. The study of their mechanism could lead to identify predictive markers, applicable to their early diagnosis and improved their management. Thus, we proposed to study the role of NK cell and T cell in the CAMELIA clinical trials which have conducted in Cambodia. The result showed that higher increase of NK cell degranulation capacity was associated with the occurrence of TB-IRIS and it could be a predictive marker. Furthermore, the hyperactivation of effector T cell and decrease of regulatory T cell were also observed. The implication of the regulatory T cell in this syndrome was not clear yet. The regulatory mechanism of this phenomenon should be further explored
10

#### Avian influenza and co-infections : investigation of the interactions in the poultry models / Influenza aviaire et co-infections : étude des interactions dans le modèle aviaire

Umar, Sajid 12 January 2017 (has links)
Ce travail vise à estimer l’impact de co-infections sur le terrain et à mieux comprendre le synergisme possible entre agents pathogènes en conditions expérimentales. Nous nous sommes intéressés à E. coli (O78) et au virus influenza faiblement pathogène (LPAIV, H6N1) dans le modèle dinde. Les oiseaux ont été infectés par voie aérosole pour reproduire l’infection respiratoire. L’excrétion virale ainsi que les lésions ont été plus importantes lors de la co-infection, ce qui suggère une patho-génicité accrue. Ces résultats montrent que E. coli et LPAIV ont un effet additif sur la maladie respiratoire lors qu’ils ont été inoculés soit simultanément soit en différé (à 3 jours d’intervalle) à des dindes naïves. En parallèle, nous avons étudié les virus respiratoires en circulation dans les élevages pakistanais. Des co-infections avec le LPAIV H9 (lignage G1) et le virus de la maladie de Newcastle (génotype VII) ont été fréquemment observées. / The purpose of this study was to assess the burden of co-infections in the field and to better understand the possible synergism between pathogens in a laboratory setting. We focussed on E. coli (O78) and low pathogenic avian influenza virus (LPAIV, H6N1) in turkey model and infected the birds via the aerosol route to reproduce respiratory disease. Viral shedding and lesions were more severe and persisted longer during coinfection indicating possible enhancement of pathogenesis for LPAIV by E. coli and vice versa. These findings all endorse our conclusions that E. coli and LPAIV exercise an additive pathogenic effect in the reproduction of respiratory disease if given simultaneously or spaced by three days between the viral and the bacterial challenges to susceptible turkeys. In parallel, we studied avian respiratory agents circulating in the field in Pakistani farms. There, we focussed on co-infections as well, targeting viruses only as a first study. We observed frequent LPAIV H9 (G1 lineage) and Newcastle disease virus (genotype VII) coinfections in the field.

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