The first detection of nematodes Ashworthius sidemi in elk Alces alces (L.) in Poland and remarks of ashworthiosis foci limitations.

Ashworthius sidemi, a nematode belonging to the family of Trichostrongylidae, is a primary parasite of the Asian deer, mainly sika deer (Cervus nippon), with which it was introduced to Ukraine, as well as Slovakia, the Czech Republic and France. Migrating red deer carried this parasite from neighboring countries to Polish territory. Until now, in Poland, this parasite has been recorded in European bison, red deer, roe deer and fallow deer. As a result of post-mortem examinations of 10 elk, 2 of them from the Augustów Forest and Biebrza Marshes, A. sidemi were found in abomasa for the first time in Poland. The intensity of the invasions was 120 and 7 specimens, respectively. This finding of Ashworthius sidemi in elk indicates a further expansion of the focus of ashworthiosis in BiaŁowieża towards the north into the Biebrza Marshes and the Augustowska Forest. The growth of the elk population and their tendency for long distance migrations can contribute to the spread of the parasitosis in much greater distances than deer. On the basis of our own research and data from the literature, the current spread of ashworthiosis in Poland is discussed.