One thousand three hundred seventy three fish specimens of eight different species from the vicinity of Kyiv, Ukraine, were examined for the presence of trypanosomes and 921 individuals were found to be infected. The prevalence of infection ranged from 24% in freshwater bream, Abramis brama (Linnaeus), to 100% in spined loach, Cobitis 'taenia' Linnaeus. The level of parasitaemia also varied significantly between generally mild infections in pikeperch, Sander lucioperca (Linnaeus), and heavy ones in C. 'taenia'. In most cases the infections with trypanosomes were asymptomatic. Cases of co-infection with species of Trypanoplasma Laveran et Mesnil, 1901 were documented for five out of eight examined host species. Molecular analysis of the 18S rDNA sequences revealed that four hosts, namely northern pike, Esox lucius Linnaeus, freshwater bream, spined loach and European perch, Perca fluviatilis Linnaeus, were simultaneously infected with two different trypanosome species. Our findings advocate the view that to avoid the risk posed by mixed infections, subsequent molecular taxonomic studies should be performed on clonal lines derived from laboratory cultures of fish trypanosomes.

Biology Centre Institute of Parasitology Czech Academy of Sciences České Budějovice Czech Republic

Faculty of Science University of South Bohemia České Budějovice Czech Republic

Life Science Research Centre Faculty of Science University of Ostrava Ostrava Czech Republic

Schmalhausen Institute of Zoology National Academy of Sciences of Ukraine Kyiv Ukraine

Zoological Institute Russian Academy of Sciences St Petersburg Russia

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