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Chemoprophylaxis is a term which describes treatment with an antimicrobial chemotherapeutic before, during or shortly after an actual or suspected exposure to an infectious agent in order to prevent clinical
disease, which may be severe or even fatal.
Lyme borreliosis is considered the most frequent ixodid-tick-transmitted human bacterial infection in the northern hemisphere. For several years there has been a debate on the prophylactic application of antimicrobial chemotherapeutics after an attached Ixodes tick was removed. Would this measure prevent a subsequent borrelia infection and would it be practical? People are exposed to tick-bites mostly during leisure spent in recreational areas which are often tick infested. The proportion of I. ricinus ticks infected with B. burgdorferi s. l. varies from area to area and in a given area also from year to year (infection rate up to a maximum of 55%). The transmission rate strongly depends on the duration of feeding, but it could be shown that the critical time of feeding is much shorter for European I. ricinus than for the North American I. scapularis or I. pacificus ticks. Nevertheless, even the low risk of complications despite the very good chance of treating erythema migrans successfully seems to justify prophylactic treatment for some investigators whilst others do not see an argument for this. Double blinded studies in the USA showed a relatively low frequency of illness after vector tick-bite and absence of disseminated
disease manifestations. The efficacy of prophylactic antibiotic treatment after tick-bites is not established. Suggestions to examine removed ticks for borrelia in order to obtain indication for prophylactic antibiotic treatment will fail in practice because of high costs and uncertainty in verifying the transmission. Do we need blinded studies in central Europe on a representative number of cases, although it is known that
Lyme borreliosis can be treated effectively even in its second and third stage and has never caused a fatal outcome? We conclude that only a reliable diagnosis of symptoms is the basis for a rational antibiotic treatment, and that instead of chemoprophylaxis for
Lyme borreliosis after a vector tick-bite the wait and watch policy is recommended.