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Gern, Lise
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Gern, Lise
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lise.gern@unine.ch
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Voici les éléments 1 - 10 sur 54
- PublicationAccès libreResolution of experimental and tick-borne Borrelia burgdorferi infection in mice by passive, but not active immunization using recombinant OspC
;Zhong, Weimin; ;Stehle, Thomas ;Museteanu, Crisan ;Kramer, Michael ;Wallich, ReinhardSimon, Markus MVaccination with outer surface protein A (OspA) of Borrelia burgdorferi prevents subsequent infection and disease in both laboratory animals and humans with high efficacy. OspA-based immunity, however, does not affect established infection due to the loss of OspA expression in the vertebrate host. We show here that repeated passive transfer of mouse and/or rabbit immune sera to recombinant GST-OspC fusion protein resulted in a dose-dependent resolution (1) of fully established arthritis and carditis as well as infection in needle-challenged C.B-17 SCID and (2) of infection in both experimentally and tick-infected BALB/c mice. Unexpectedly, active immunization of disease-susceptible AKR/N mice with GST-OspC only led to prevention but not resolution of disease and infection, in spite of high serum titers of OspC-specific Ab and the expression of ospC in tissue-derived spirochetes. The data suggest that the efficacy of OspC antibody-mediated immunity depends on the immunological history of the recipient and/or environment-dependent regulation of OspC surface expression by spirochetes in vivo. The results encourage further attempts to develop therapeutic vaccination protocols against Lyme disease. - PublicationAccès libreEcology of Borrelia burgdorferi sensu lato in Europe(2002)
; Humair, Pierre-François - PublicationAccès libreBorrelia burgdorferi in a focus of Lyme borreliosis: epizootiologic contribution of small mammals
;Humair, Pierre-François ;Turrian, N; The contribution of woodmice (Apodemus sylvaticus), yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) was compared in a focus of Lyme borreliosis in Switzerland during a 7 months' study. All three species of mice and one species of shrews (Sorex araneus) were shown parasitized by infected Ixodes ricinus immatures. About 14% of larvae and 50% of nymphs collected on small mammals were infected with B. burgdorferi. Spirochetes were isolated from blood of 3 woodmice and one yellow-necked mouse. The infectious status of rodents was estimated by tick xenodiagnosis. Prevalence of infected rodents ranged from 20% to 44%. Mice presented a higher potential infectivity than voles. The prevalence of infected rodents showed a seasonal variation. - PublicationAccès libreComparative considerations on the epidemiology of Lyme borreliosis and tick-borne encephalitis in Switzerland(1991)
; ;de Marval, F.In Switzerland, the spirochete Borrelia burgdorferi and tick-borne encephalitis virus infect the human population. These infections may cause serious pathogenic effects to men and domestic animals. The tick Ixodes ricinus is the vector of both microorganisms. The distribution of the virus is concentrated in small foci scattered in some regions. In these areas, the infection occurs in less than 1 % of the ticks. The distribution of the spirochete is larger and more regular in the Swiss territory and B. burgdorferi is present in 5 to 50 % of/, ricinus. It is the aim of this paper to try to explain how both types of foci occur, considering especially the problem of small mammals as reservoirs for the bacterium and the virus. - PublicationAccès libreDéveloppement de Borrelia burgdorferi dans la tique Ixodes ricinus(1989)
; ;Zhu, Z.Nous avons étudié le développement de Borrelia burgdorferi dans son vecteur européen, la tique Ixodes ricinus, lors du repas sanguin. Nos résultats montrent que durant la phase de gorgement lente, les spirochètes présents dans l'intestin se multiplient. Chez certains individus, quelques spirochètes traversent la paroi intestinale et produisent une infection systémique de la tique. La présence de borrélies dans les conduits des glandes salivaires semblent prouver leur transmission via la salive chez les femelles d'I. ricinus. - PublicationAccès libreBorrelia burgdorferi in ticks of the Canton Tessin (Switzerland)(1990)
;Miserez, V.; In the northern Alps it is hard to find an Ixodes ricinus population which does not harbour Borrelia burgdorferi. The infection rates range from 5 to 34% for adults and nymphs to 3.1% for larvae. This study shows that the infection rates on the southern side of the Alps are similar, at 25% for adults, 36.2% for nymphs and 3.2% for larvae. With respect to tick species other than I. ricinus, we did not succeed in finding any spirochetes in Dermacentor marginatus, Haemaphysalis punctata, Ixodes hexagonus, Rhipicephalus sanguineus. - PublicationAccès libreLyme disease
; Falco, R.CLa borréliose de Lyme qui est, dans l'hémisphère nord, la plus répandue des maladies à transmission vectorielle, est due à des bactéries appartenant au genre Borrelia burgdorferi. Il s'agit d'une maladie plurisystémique qui affecte essentiellement la peau, le système nerveux le cœur et les articulations. En Europe, le vecteur de la maladie est la tique Ixodes ricinus; aux États -Unis d'Amérique les deux vecteurs principaux sont la tique I. scapularis dans les régions du nord-est et du centre-ouest et I. pacificus sur la Côte Ouest. Plusieurs espèces de petits et moyens mammifères ou d'oiseaux terrestres servent de réservoirs à la bactérie dans les zones endémiques. Le pronostic est excellent, surtout lorsque la maladie de Lyme est diagnostiquée en phase initiale et traitée immédiatement. La prophylaxie repose sur deux méthodes: l'immunisation préventive, d'une part, et la mise en œuvre de mesures permettant d'éviter les piqûres de tiques et de lutter contre ces vecteurs, d'autre part., Lyme borreliosis, the most common vector-bome disease in the northern hemisphere, is caused by bacteria belonging to the Borrelia burgdorferi complex. The disease is multisystemic, affecting mainly the skin, nervous system, heart and joints. In Europe, the vector of the disease is the tick Ixodes ricinus, whereas in the United States of America, two primary tick vectors exist, namely: I. scapularis in the north-eastern and mid-western regions and I. pacificus on the west coast. Several species of small and medium-sized mammals and ground-feeding birds serve as reservoirs for the bacteria in endemic areas. The prognosis for patients with Lyme borreliosis is excellent, particularly when diagnosed and treated early in the course of infection. Prevention of Lyme borreliosis can be achieved using two approaches, either prevention of infection by immunisation, or prevention of tick bites through avoidance, personal protection and tick control., De todas las enfermedades vehiculadas por vectores, la borreliosis de Lyme, causada por bacterias pertenecientes al complejo Borrelia burgdorferi, es la más común en el hemisferio norte. Esta enfermedad de carácter multisistémico afecta principalmente la piel, el sistema nervioso, el corazón y las articulaciones. En Europa, el vector de la enfermedad es la garrapata Ixodes ricinus. En los Estados Unidos de América, por su parte, existen dos garrapatas que ejercen de vectores primarios: I.scapularis en las regiones del noreste y el medio oeste, e I.pacificus en la costa oeste. En las áreas endémicas varias especies de mamíferos pequeños y medianos y de aves de alimentación terrestre sirven de reservorio de las bacterias. Los pacientes afectados de borreliosis de Lyme presentan un pronóstico excelente, sobre todo cuando se diagnostica y trata la infección en sus fases iniciales. Para prevenir esta enfermedad caben dos procedimientos distintos: prevenir la infección con medidas de inmunización; o impedir la mordedura de la garrapata previniendo esta posibilidad, protegiéndose del contacto y luchando contra sus poblaciones. - PublicationAccès libreTiques et borréliose de Lyme en Suisse occidentaleLa maladie de Lyme est une maladie dont l'agent responsable, une bactérie, Borrelia burgdorferi, n'a été découvert qu'au début des années 1980. Elle se manifeste de manière proteiforme et provoque des manifestations dermatologiques, neurologiques, cardiaques ainsi que des arthrites. Trois espèces de bactéries, B. burgdorferi s.s. , B. garinii et B. afzelii sont responsables de ces manifestations chez l'homme. Elles sont transmises en Europe par la tique Ixodes ricinus. Cette tique est fréquente dans certaines régions de Suisse où elle peut atteindre une densité de 300 tiques /100m2. Son infection par B. burgdorferi peut s'élever à près de 50%. Actuellement la plus forte densité de tiques infectées a été observée à Neuchâtel où cette densité peut atteindre 69 tiques infectées/100 m2. Les tiques s'infectent en se nourrissant sur des rongeurs sauvages (micromammifères, écureuils), sur des oiseaux ou sur des hérissons. Une relation spécifique a été observée entre B. afzelii, B. burgdorferi ss et les rongeurs alors que B. valaisiana et B. garinii se rencontrent chez les oiseaux.
- PublicationAccès libreNatural history of Borrelia burgdorferi sensu lato
; Humair, Pierre-FrançoisLyme borreliosis is a zoonosis: its causative agent, B: burgdorferi, circulates between ticks and a large range of vertebrates. Identification of the hosts which are responsible for the infection of the vectors is extremely important to determine the potential risk of infection in an habitat. Various small mammals and bird species are considered reservoirs for the Lyme disease spirochetes. Grey and red squirrels, hedgehogs as well as hares and rabbits can develop an infection and transmit B. burgdorferi sensu lato to feeding ticks. In Eurasian endemic areas, many different Borrelia species circulate between ticks and vertebrate hosts. Studies have shown that European and Asian genospecies are associated with specific groups of vertebrate hosts, such as B. valaisiana and B. garinii with birds, B. afzelii with small mammals and B. burgdorferi ss and B. afzelii with red squirrels. However, such associations are not always observed as in Japan where B. garinii, B. afzelii and unidentified Borrelia species are found in small mammals. Some enzootic cycles involving tick species which do not feed at all on humans or which rarely feed on humans have been described in Europe and USA. It is likely that many existing enzootic foci have yet to be discovered. The circulation of B. burgdorferi in silent foci does not have important implications for human health, but it demonstrates the complexity of the ecology of this microorganism and the variety of ecological niches this spirochete can occupy. - PublicationAccès libreThe Ecology of Lyme Borreliosis in Europe(1992)
; ;Burgdorfer, Willy; Krampitz, H. E.