La borréliose de Lyme en Belgique

La borréliose de Lyme est une spirochétose transmise à l’homme et à de nombreux animaux des régions tempérées de l’Ancien et du Nouveau Monde, principalement par les tiques dures des bocages et des forêts. Elle est nouvellement décrite, mais elle est certainement endémique depuis des millénaires (Mardi Ras et al., 1997). Cette « maladie de Lyme » rentre depuis plus de 15 ans dans le diagnostic différentiel de nombreuses entités cliniques en médecine humaine, mais il ne faut pas oublier toute son importance en médecine vétérinaire et en écologie animale. L’agent causal, Borrelia burgdorferi sensu lato, est une bactérie de la famille des Spirochaetaceae. Difficilement cultivable, ce spirochète a justifié une amélioration constante des techniques bactériologiques pour sa mise en évidence et de biologie moléculaire pour sa taxonomie. La reconnaissance progressive de ses protéines antigéniques a sans cesse amélioré les méthodes diagnostiques ainsi que les choix des futurs vaccins. Le laboratoire de Sérologie bactérienne et parasitaire des Cliniques Universitaires St-Luc s’est investi depuis 1983 dans le domaine des spirochétoses, selon un choix stratégique. En effet, en plus de la syphilis et d’autres tréponématoses à diagnostiquer au retour des zones tropicales, ce dut la leptospirose ictéro-hémorragique qui justifia alors la mise au point d’un Enzyme Linked Immunosorbent Assay (ELISA) pour dépister les IgM et les IgG spécifiques. Et outil fut également utilisé dans le centre de référence national, à l’Institut de Médecine Tropicale d’Anvers. De là partit la décision de développer, en collaboration avec l’Unité de Virologie de la K.U.L., de nouvelles méthodes sérologiques pour dépister les anticorps spécifiques anti-Borrelia burgdorferi en Belgique. Cette thèse est divisée en deux parties : une introduction, dans laquelle sont présentées les principales données épidémiologiques, cliniques, diagnostiques et thérapeutiques de la borréliose de Lyme. Une seconde qui reprend la contribution originale de notre laboratoire dans 4 domaines : la séro-épidémiologie en Belgique, la recherche des Borrelia dans les vecteurs, l’utilisation de la Polymerase Chain Reaction appliquée à ces spirochètes et la recherche clinique par la technique du Western Blot. Une discussion est ensuite ouverte sur les problématiques actuelles ainsi que sur les perspectives vaccinalesThèse de doctorat en sciences biomédicales -- UCL, 199

Tiques Ixodidae parasites d'oiseaux et leur rôle pathogène

The authors first give the list of Ixodid ticks which can be found on avian species in Europa and recall their pathogenic role for birds and mammals, when they are not specific, and, when they are, their eventual role as vectors or reservoir of germ for different kinds of infectious agents, more particularly for Borrelia burgdorferi, the agent of Lyme borreliosis. Concerning that zoonosis, the authors were mostly interested by the presence of B. burgdorferi in Ixodes (Trichotoixodes) pari Leach 1815 (= Ixodes frontalis (Panzer, 1798)), a very specific tick for birds; considered generally as a rare species, but in fact a very common one. Research of B. burgdorferi (sensu late) by indirect immunofluorescence revealed the presence of that agent in near 10 per cent of studied I. pari, including all evolutive stages and gorged states. Observation of B. burgdorferi in not yet fed larvae collected on the grass, with a non negligible frequency, results in the possible transmission of this infectious agent from infected female to its progeny, by transovarial passage. Existence of such a possibility let the authors think that I. pari is very likely a vector from bird to bird and a true germ reservoir for the zoonosis

[Neuroborreliosis Revealed By Epilepsy]

After two seizures, a 13 year-old boy experienced headache, fatigue and loss of appetite over a period of 3 weeks. There was a bilateral papilledema with normal visual acuity. CT and MRI disclosed two ischemic foci, that were interpretated as evidence of vasculitis. High serum levels of IgG and IgM antibodies specific to Borrelia burgdorferi, were present. The patient had attended an outdoor scout camp in a area, in south-east Belgium, known to be endemic for tick-born borreliosis. The clinical symptoms, the levels of the specific antibodies and the radiologic abnormalities responded dramatically to treatment. We believe that seizures in this case were related to cerebral vasculitis. This case confirms the extreme diversity of the neurological manifestations of Borreliosis

Polyclonal and oligoclonal IgA synthesis in the cerebrospinal fluid of neurological patients: an immunoaffinity-mediated capillary blot study

An intrathecal synthesis of IgA has been reported in various neurological disorders. However, the frequency of its occurrence and the electrophoretic characteristics of the locally produced IgA remained a matter of controversy. We developed a sensitive immunoaffinity-mediated capillary blot technique for the detection of polyclonal and oligoclonal IgA in the CSF of 115 patients with various neurological disorders. Paired CSF and serum samples containing 50 ng IgA after appropriate dilutions were submitted to isoelectric focusing in agarose gels; IgA was then blotted onto a polyvinylidene difluoride sheet coated by an anti-IgA antiserum or by infectious antigens. The immunoblots were revealed by an alkaline phosphatase-conjugated anti-IgA antiserum. Only five samples displayed CSF-restricted oligoclonal IgA bands, including two out of 33 from MS patients. In herpetic encephalitis (n = 5) and varicella-zoster meningitis (n = 2), a strong intrathecal production of virus-specific IgA antibodies was detectable. In such cases, faint oligoclonal IgA antibodies were superimposed on a polyclonal background. A weak local production of anti-Borrelia burgdorferi IgA antibodies was present in two out of four cases of neuroborreliosis

Evidence for the involvement of different genospecies of Borrelia in the clinical outcome of Lyme disease in Belgium

In addition to Borrelia burgdorferi, recognized as the aetiological agent of Lyme disease, at least two separate genospecies have recently been described. A relationship between infection by strains belonging to different genospecies and clinical outcome has been suspected. In this paper, 9 cases of Lyme arthritis were attributed to infection by B. burgdorferi sensu stricto, 18 cases of neuroborreliosis to B. garinii and one case of acrodermatitis chronica atrophicans to a strain of B. afzelii. These conclusions were based on the preferential reactivity of sera with antigens of given strains in Western blots and on residual reactivity after absorption of sera with antigens of representative strains. No conclusion could be reached concerning sera of 10 patients with erythema migrans