Le virus Lassa entraine une fièvre hémorragique endémique en Afrique de l’Ouest et représente un problème de santé publique. Les connaissances sur la pathogénèse et les réponses immunitaires associées à la maladie sont partielles. Nous avons suivi les paramètres pathologiques, virologiques et immunologiques associés aux infections létales et non létales du LASV chez le singe cynomolgus. Le tableau clinique a été caractérisé par une dépression, une anorexie, une perte de poids et une asthénie chez les animaux survivants, tandis que ces mêmes symptômes ont été accompagnés de fièvre, de difficultés respiratoires et d’épistaxis chez les animaux infectés par une dose létale. Seuls ces derniers ont montré une perturbation des paramètres de coagulation, une rhabdomyolyse et une hausse des marqueurs de lésions rénales. Nous avons observé un tropisme radicalement différent en fonction de la sévérité de la maladie, avec une dissémination virale dans les organes plus importante et plus rapide chez les animaux décédés, la présence de particules infectieuses plus nombreuses et des modifications anatomopathologiques plus sévères. Une réponse immunitaire innée et adaptative précoce et puissante a été associée avec le contrôle de l’infection et la survie tandis que les infections fatales ont été caractérisées par une réponse inflammatoire ressemblant au choc septique, une défaillance de la réponse immunitaire ainsi qu’une réplication virale incontrôlée. Cette étude permet d’améliorer nos connaissances de la pathogénèse de la fièvre de Lassa et d’apporter des marqueurs d’infection prédictifs de la maladie / Lassa virus causes a hemorrhagic fever endemic in West Africa and represents a threat for civilians. The pathogenesis and the immune responses associated with the disease are poorly understood. We followed pathological, virological and immunological parameters associated with fatal and non-fatal Lassa virus infection in the cynomolgus monkey. The clinical picture was characterized by depression, anorexia, weight loss and asthenia in survivors whereas the same symptoms were supported by fever, respiratory difficulties and epistaxis in animals infected with the lethal dose. Only fatalities have shown coagulation parameters dysfunction, rhabdomyolysis and an increase of renal function markers. We observed a different viral tropism in a function of the disease severity, with viral dissemination in organs that was more important and faster in fatalities, the appearance of numerous infectious particles number and more severe pathologic changes. Early and robust innate and adaptive immune response has been associated with the control of infection and recovery whereas fatal infections were characterized by a sepsis like inflammatory response, defective immune response as well as uncontrolled viral replication. This study sheds light on the pathogenesis of Lassa fever and reveals infection markers predictive of the disease outcome

Dengue fever (DF) and dengue hemorrhagic fever (DHF) are emerging infectious diseases which are endemic in many regions of the globe, many of which are resource-poor areas. DHF and DF impose a severe economic health burden in tropical and subtropical areas. Dengue virus causes an acute febrile illness that can be a self-limited febrile illness, as seen in most cases of DF, or a life-threatening illness with plasma leakage and shock, as seen in cases of DHF. A systematic review of the literature revealed gaps in the knowledge base of clinical laboratory findings of dengue illness with regards to longitudinal dynamics and classification and predictive modeling of disease severity. The objective of this thesis was to investigate the utility of clinical laboratory variables for classification and prediction of disease outcomes. The data used in this investigation was derived from a prospective study of Thai children presenting to either of two study hospitals within 72 hours of onset of an acute febrile illness. Systematic data collection, including clinical laboratory parameters, and routine clinical management continued each day until 24 hours after the fever had subsided. A final diagnosis of DHF, DF, or other febrile illness (OFI) was assigned by an expert physician after chart review. The first research objective of this study was to describe the temporal dynamics of clinical laboratory parameters among subjects with DHF, DF, or OFI. Data were analyzed using lowess curves and population-average models. Quadratic functions of clinical variables over time were established and demonstrated significantly divergent patterns between the various diagnostic groups. The second research objective was to establish and validate tools for classification of illness severity using easily obtained clinical laboratory measures. Bivariate logistic regression models were established using data from one hospital in an urban area of Thailand as a training data set and validated with a second data set from a hospital in a rural area of Thailand. The validated models maintained a high sensitivity and specificity in distinguishing severe dengue illnesses without using the hallmark indicators of plasma leakage. The third research objective used classification and regression tree (CART) analysis to established diagnostic decisions trees using data obtained on the day of study enrollment, within the first 3 days of acute illness. Decision trees with high sensitivity were established for severe dengue defined either as: 1) DHF with evidence of shock (dengue shock syndrome, DSS); or 2) DSS or dengue with significant pleural effusion. This study expands existing knowledge of the potential utility of clinical laboratory variables during different phases of dengue illness. The application of the results of these studies should lead to promising opportunities in the fields of epidemiological research and disease surveillance to reduce the health burden, and improve the clinical management, of dengue illness. Future directions involve application of these algorithms to different study populations and age groups. Additionally, other analytical techniques, such as those involving CART analysis, can be explored with these data.

Hantaviren (Familie Bunyaviridae) sind Erreger, die von Nagetieren auf den Menschen übertragen werden und Hämorrhagische Fieber mit Renalem Syndrom (HFRS) auslösen. Die vorgelegte Arbeit beinhaltet derartige Ergebnisse zu zwei europäischen Hantaviren, dem Dobravavirus (DOBV) und dem Tulavirus (TULV). DOBV ist ein wichtiger HFRS-Erreger in Europa. DOBV Stämme kommen in mindestens zwei Nagerspecies, der Gelbhalsmaus (Apodemus flavicollis) und der Brandmaus (A. agrarius) vor. In Übereinstimmung mit diesen natürlichen Wirten bilden die Virusstämme zwei genetische Linien: DOBV-Af und DOBV-Aa. Die phylogenetischen Analysen von den Nukleotidsequenzen der S-, M- und L-Segmente von sympatrisch vorkommenden DOBV-Af und DOBV-Aa Stämmen aus Mitteleuropa zeigten das Vorkommen von Reassortmentprozessen der Genomsegmente während der Evolution der Virusspecies. Ausserdem, wurde die virale Nukleotidsequenz aus einem DOBV-seropositiven HFRS-Patienten aus Detschland amplifiziert. Damit wurde erstmalig der molekulare Beweis erbracht, dass DOBV in Mitteleuropa HFRS auslöst und dass die DOBV-Aa Linie humanpathogen ist. Aus einer in der Slowakei gefangenen A. agrarius Maus haben wir ein neues Virusisolat gewonnen, welches "Slovakia (SK/Aa)" genannt wurde. SK/Aa ist das bisher einzige Virusisolat, das die DOBV-Aa Linie repräsentiert. Es wurde gemeinsam mit einem Isolat der DOBV-Af Linie zur vergleichenden Typisierung der Antikörper von mitteleuropäischen HFRS-Patienten mittels Fokusreduktionsneutralisationstest eingesetzt. Die Seren der meisten Patienten zeigten die höchsten neutralisierenden Antikörpertiter gegenüber SK/Aa, was die Schlussfolgerung zulässt, dass DOBV-Aa Stämme für die meisten DOBV-Infektionen in Mitteleuropa verantwortlich sind. TULV wird durch die Feldmaus (Microtus arvalis) beherbergt. Die Fähigkeit zur Auslösung von HFRS war bisher wenig bekannt. Wir haben den ersten Fall von HFRS gefunden, der mit einer TULV Infektion assoziiert ist. Aus demselben geographischen Gebiet in Nordostdeutschland konnten aus Feldmäusen TULV Nukleotidsequenzen amplifiziert werden. In phylogenetischen Analysen clustern sie mit Stämmen aus Polen und bilden mit diesen gemeinsam eine eigene, neue genetische Linie. Ausser dem hier untersuchten DOBV und dem länger bekannten Puumalavirus ist TULV offenbar das dritte Hantavirus, das in Mitteleuropa HFRS hervorruft. / Hantaviruses (Bunyaviridae family) are rodent-borne bunyaviruses that cause hemorrhagic fever with renal syndrome (HFRS) in Eurasia. This thesis presents novel data about two European hantaviruses, Dobrava virus (DOBV) and Tula virus (TULV). DOBV is an important etiologic agent of HFRS in Europe. DOBV strains were found to be hosted by at least two different rodent species, yellow-necked mouse (Apodemus flavicollis) and striped field mouse (A. agrarius). According to their natural hosts they form the distinct genetic lineages DOBV-Af and DOBV-Aa, respectively. We have determined and analysed the complete S and M, and partial L segment nucleotide sequences of sympatrically occurring DOBV-Af and DOBV-Aa strains from Central Europe. Molecular phylogenetic analyses gave evidence for genetic reassortment in the evolution of the virus species. Moreover, we amplified a DOBV-Aa nucleotide sequence from a DOBV-seropositive HFRS patient from Germany. This is the first molecular identification of human infection by DOBV in Central Europe and the first direct proof that a virus strain related to the DOBV-Aa lineage, carried by A. agrarius rodents, is able to cause HFRS. Under biosafety level 3 conditions, we have established a DOBV isolate named Slovakia (SK/Aa) from an A. agrarius animal captured in Slovakia. SK/Aa, as the only isolate clearly belonging to the DOBV-Aa lineage, can be taken as the representative of this virus lineage. The new virus isolate, in comparison to a DOBV-Af strain, was used for serotyping neutralising antibodies of HFRS patients in Central Europe by the use of a focus reduction neutralisation assay. Most patients'' sera exhibited a higher end-point titer towards SK/Aa suggesting that DOBV-Aa strains are responsible for most of the DOBV HFRS cases in this region. TULV is carried by European common voles (Microtus sp.). Its pathogenic potential for humans was rather unknown. We have described the first case of HFRS which can be associated with TULV infection. Moreover, TULV strains detected in M. arvalis near the home village of the patient in North-East Germany clustered with strains from Poland and represent a new, well-supported genetic lineage within the TULV species. In addition to DOBV and longer known Puumala virus, TULV is most likely an additional causative agent of HFRS in Central Europe.

Made available in DSpace on 2016-12-23T13:47:02Z (GMT). No. of bitstreams: 1 Creuza Rachel Vicente.pdf: 3384838 bytes, checksum: c3eca90bf4886725c29d5e5904662f2b (MD5) Previous issue date: 2012-03-15 / Introdução: A ocorrência da dengue sofre influência do comportamento, estrutura social e distribuição da população e sua transmissão pode variar de acordo com as áreas do município. Seu prognóstico depende do diagnóstico precoce e da imediata instituição do tratamento. Este estudo avalia fatores associados à ocorrência da dengue, enfatizando a distribuição territorial e os relacionados à dengue grave. Métodos: Foram realizados dois estudos, sendo um transversal e outro retrospectivo, sobre a totalidade dos casos de dengue que ocorreram em Vitória no ano de 2011, com base nos dados do Sistema de Informações de Agravos de Notificação. Resultados: Entre os casos confirmados, 53,4% ocorreram em mulheres, 74,7% em maiores de 15 anos e 6,3% evoluíram para gravidade. Os territórios de saúde de Jardim Camburi, Maruípe, Ilha das Caieiras, Santa Martha e Santo André responderam por 41,6% das notificações. Quase metade dos casos foram concluídos por critério laboratorial e, destes, 80% realizaram sorologia. Em todos os territórios, mais de 20% dos notificados realizaram sorologia e, na maioria, mais de 51% tiveram resultado positivo. Nas regiões de São Pedro, Maruípe e Santo Antônio, os afetados eram principalmente jovens, enquanto nas regiões Continental e Forte São João, eram pessoas mais velhas. Dos 371 casos de dengue grave, 78,7% foram de dengue com complicações e 21,3% de febre hemorrágica da dengue. Sessenta e sete por cento dos casos ocorreram em pessoas com idade superior a 15 anos. As Regiões de Saúde de Maruípe e São Pedro foram responsáveis por mais da metade dos casos de dengue grave (56,35%). Houve associação estatisticamente significante entre ocorrência de febre hemorrágica da dengue com idades mais jovens (menores de 15 anos) e maior tempo decorrido na procura por atendimento. Também houve associação estatisticamente significante entre maior tempo decorrido na procura pelo atendimento e idade menor que 15 anos. Os casos de dengue grave estavam concentrados em faixas etárias mais jovens na região de São Pedro. Conclusão: A distribuição territorial não foi uniforme, e pode ser determinada pela alta densidade populacional e pelas condições socioeconômicas. As diferenças de idade entre as regiões podem estar relacionadas à incidência da doença nestes locais. A grande proporção de sorologias positivas e o número de exames realizados possibilitaram uma boa detecção e acompanhamento dos casos de dengue. Os resultados corroboram os de outras pesquisas que apontam uma mudança no perfil da febre hemorrágica da dengue nas Américas e no Brasil, com crescente acometimento de jovens, e apontam a demora no tempo de procura por atendimento, baixa qualidade urbana e alta endemicidade como possíveis fatores de risco. / Introduction: The incidence of dengue, influenced by human behavior, social structure and population distribution, may vary with respect to the geographical areas of a given city. Its prognosis depends on early diagnosis and prompt initiation of treatment. This study evaluates factors related to the occurrence of dengue, emphasizing the territorial distribution and risk factors for severe dengue. Methods: A cross-sectional and a retrospective study on all cases were conducted with dengue cases of Vitória in 2011, based on data from the Information System of Notifiable Diseases (SINAN). Results: 53.4% of confirmed cases occurred in women, 74.7% were 15 years old or older, and 6.3% were severe forms. The health territories of Jardim Camburi, Maruípe, Ilha das Caieiras, Santa Martha and Santo André accounted for 41.6% of reported cases. Almost half of the cases had final classification based on laboratory tests, and of these, 80% were submitted to serological tests. Of all territories, more than 20% of those reported cases had been submitted to serological tests, and more than 51% of them had a positive result. In the regions of São Pedro, Santo Antônio e Maruípe, the affected individuals were younger, while in Continental Region and Forte São João Region, they were older. Of the 371 cases of severe dengue, 78.7% were classified as dengue with complications and 21.3% were classified as dengue hemorrhagic fever, whose age distribution disclosed a frequency of 67.1% in individuals 15 years old or older. Regions of Maruípe and São Pedro were responsible for over half of cases of severe dengue (56.3%). There was a statistically significant association between the occurrence of dengue hemorrhagic fever and younger ages (under 15 years) and longer time interval between the beginning of symptoms and seeking for care. People younger than 15 years old take longer to seek for care. The frequencies of cases of severe dengue were concentrated in younger age groups in the region of São Pedro. Conclusion: The geographical distribution was not uniform, and can be influenced by the high population density and socioeconomic conditions. The age differences between regions may be related to disease incidence in these locations. A large proportion of positive tests and a great number of tests performed allowed a good detection and monitoring of dengue cases. The results corroborate those of other studies that indicate a change in the profile of dengue hemorrhagic fever in the Americas and Brazil, with growing involvement of young people, and indicate the time delay in seeking treatment, urban poor quality and high endemic scenario as possible risk factors.