Mixed natural focus of tick-borne encephalitis, tularemia and haemorrhagic fever with renal syndrome in west Slovakia

Abstract

Total of 923 small mammals of 7 species were collected in locality Záhorská Ves, West Slovakia, in 1990-1992. Among examined small mammal species it was Clethrionomys glareolus (48.7% of total, 17.5% positive for tick-borne encephalitis (TBE) virus antibodies), Apodemus flavicollis (29.7% of total, 17.5% positive), A. sylvaticus (11.3% of total, 16.3% positive), and Microtus arvalis (6.2% of total, 10.5% positive). The most abundant tick species (larval and nymphal stages) on small mammals was Ixodes ricinus. The extensity of infestation was 35.1-50.7%, and the intensity of infestation ranged in average from 4.1 to 7.8 ticks per animal. Out of 884 small rodent serum samples 16.9% had neutralizing antibody to TBE virus. Eight TBE virus isolates were recovered, six from C. glareolus and one each from A. flavicollis and A. sylvaticus; seven isolates were from brain tissue and one was from a pool of lung and liver tissues. One strain of Francisella tularensis was isolated from a pool of spleens of four C. glareolus collected in August 1991. Hantavirus antigens were detected in lung tissues of four M. arvalis collected in July and November 1990-1992. Antibody to Hantaan virus was detected by ELISA in one serum sample of A. flavicollis (titer 1:256) and antibody to Puumala virus in one serum sample of C. glareolus (titer 1:16).