The European problem of spotted fever group rickettsiae, transmitted by ticks: biology, ecology, detection

The genus Rickettsia is composed of obligatory intracellular gram−negative bacteria associated with arthropods: ticks, mites and insects. The genus was found to comprise the sub−groupings: the spotted fever group (SFG) and the typhus group (TG). Members of the SFG rickettsiae are usually associated with ixodid ticks which transfer them to vertebrates via arthropod secretions and between themselves transstadially and transovarially. Rickettsiosis is a complex pathogenic condition which takes on a number of various forms, depending on aetiological factors prevalent locally. Symptoms of rickettsiosis are similar to those occurring in many other tick−borne diseases. The necrotic skin lesion is a typical sign of spotted fever−group rickettsioses. The definition of SFG species has been recommended to use combined methods: rickettsiae detection and identification should be carried out based on serological tests and molecular techniques. Those recommended among the latter include PCR, PCR−RFLP, macrorestriction analysis by pulse−field gel electrophoresis and sequencing. The SFG rickettsiae are present in the Old Continent for example in Italy, France, Sweden, Denmark or Slovakia. Rickettsiae have been detected in patients and ticks from genus Ixodes and Dermacentor. The bacteria of SFG (Rickettsia helvetica) is present in ticks Ixodes ricinus from northern Poland creating potential danger for humans and animals.