EN
The studies were carried out in Kosewo Górne in the Mazurian District (North-East region of Poland), in September 1995, September 1996 and between May 1997 and June 1998 each month. The animals were trapped in live traps, and after study they were marked and released. The infection of trypanosomes was detected using microhaematocrit centrifugation technique and in blood smears. The intensity of infection had the range from 50 to 150000 individuals in 1ml of blood. The maximal prevalence of infection was in August and September and there were 45% and 38% of infected voles respectively. The infection was detected also in May 1998, in other months the prevalence had low level. There were no individuals of bank vole infected in succecding months. The females of bank vole are more often infected with trypanosomes than males.