RELAPSING FEVER IN EUROPE
TBRF borreliosis are considered to be emerging diseases. The estimated distribution of the disease in Europe is along the southern parts of the Mediterranean countries(59).
In this region, three zoonotic TBRF are present with a sporadic occurrence: B. hispanica with the vector Ornitho- doros erraticus erraticus is found in the Mediterranean region (Portugal, Spain, Cyprus, Greece and North Africa). The natural hosts of B. hispanica are wild rodents. In Portugal and Spain, the vector has adapted to bite domestic pigs and to live in their environment. This adaptation has possibly made humans more prone to be bitten by the vector, and HRF have been diagnosed sporadically in Spain during the 20th century. Disease caused by B. his- panica is among the less severe HRF.A new non-culturable RF Borrelia species was found in southern Spain in 1996(60). It was isolated from three patients with RF and from the B. hispanica vector O. erraticus erraticus. Molecular analyses have shown that the spirochaete is related to, but outside, the monophyletic group of B. hispanica, B. crocidurae and B. duttons'. The reservoir is not known, but rodents are suggested.
Borrelia crocidurae is present in Turkey, the Sahel region, and West and North Africa. It is transmitted by the tick O. erraticus sonrai. Typical hosts for the tick are rodents (mainly rats) and insectivores. HRF caused by B. crocidu- rae is generally benign, but neurological complications may occur.
Close to Europe’s boundaries in the south- east, three other TBRF borreliosis are present, namely: B. persica (vector: O. tholozans)(61); B. caucasica (vector: O. asperus, former O. verrucosus); and B. Iatyschewii (vector: O. tarta- kovsky ²) (Table 27.1).