Accidental discovery of Trypanosoma theileri in the in vitro culture of the heifer lymphocytes.

The diagnostics of the Trypanosoma sp. invasion by means of the classic methods i.e. the methods of thin smears or thick drop or even the microhematocrite method, especially when intensity of infection is low, is very difficult. In our climatic zone, trypanosomosis is usually considered as an exotic disease. An opportunistic model of the infection with the parasite and a lack of current data on the prevalence of T. theileri in the cattle in Poland cause that it is neglected as a potential reason of contamination of tissue cultures in cattle. We showed the presence of T. theileri in culture of isolated lymphocytes from one of six heifers examined. It seems that the prevalence of the invasion of the parasite is not very intense but it should be considered as a possible threat for bovine cell culture. It is also worth including this parasitosis in the differential diagnostics of other diseases that are infectious and/or proceed with symptoms of immunosuppression.