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Labordiagnostische Testverfahren

Ticks are obligate haematophagous acarines that parasitize every class of vertebrate (including man) and have a worldwide distribution. An increasing awareness of tick-borne diseases among clinicians and scientific researchers has lead to the recent description of a number of emerging tick-borne bacterial and viral diseases. Since the identification of Borrelia burgdorferi as the agent of Lyme diseases in 1982, 11 tick borne human bacterial pathogens have been described in Europe. Several human diseases in Europe are caused by viruses transmitted by tick bite. These viruses belong to the genus Flavivirus, and include tick-borne encephalitis virus, Omsk haemorrhagic fever virus, louping ill virus, Powassan virus, Nairovirus (Crimean-Congo haemorrhagic fever virus) and Coltivirus (Eyach virus). All of these viruses cause more or less severe neurological disease, and some are also responsible for haemorrhagic fever. The epidemiology, clinical picture and methods for diagnosis will be detailed in this lecture. The hard tick Ixodes ricinus, which acts as a vector for Borrelia burgdorferi and Tick-borne encephalitis virus (TBE), is also able to transmit other human pathogens, such as Anaplasma, Rickettsia and Babesia. In Switzerland B. burgdorferi is the major tick-borne disease in humans (3, 000 – 5, 000 cases / year) followed by a much smaller extent by TBE. Relatively little is known about other bacterial infections in terms of seroprevalence and their association with human diseases in Switzerland. In the follow-up of a tick bite clinicians are focused mainly on symptoms known and associated with those two infections. In Europe, Lyme borreliosis is caused by at least three species, B. burgdorferi sensu stricto, B. afzelii and B. garinii. Thus microbiological diagnosis in European patients must consider the heterogeneity of Lyme disease borreliae for development of diagnostic tools such as PCR primers and diagnostic antigens. Under these conditions proper screening and confirmatory assays, fulfilling high requirements in terms of sensitivity and specificity, are required. At present, detection rates for serum antibodies, especially in Stage I Lyme disease (range 20-50%), are not sufficient. Because erythema migrans, the first clinical sign of an acute Lyme borreliosis, appears in Europe in only 30-50% of cases (in contrast to over 80% in America) there is a need for a test method with higher sensitivity at this stage of infection.

Lyme-Borreliose, Borrelia burgdorferi, Labordiagnostik

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