Causative agent: Babesia bigemina, Babesia major
There are other species of Babesia that cause Babesiosis in other host species. B.bigemina and B.major are the only species reported to cause babesiosis in bison (40,41). Babesia are protozoal parasites that cause intravascular hemolysis.
Babesia are transmitted by tick vectors. In the USA the tick vector for B.bigemina has been eradicated. B.major has been reported to cause babesiosis in bison in Britain (40). In the USA, babesiosis has been induced in bison by experimental infection with B.bigemina(41). Natural infections of bison with B.bigemina have not been reported.
Clinical signs:
Clinical signs include fever, jaundice, hemoglobinuria (frothy dark red urine), heavy breathing, and anorexia (40,41).
Postmortem findings:
Postmortem findings include enlarged spleen, enlarged liver, jaundice, and hemoglobinuria. (40,41)
Diagnosis:
Babesia may be observed in smears made from blood taken from live infected bison, or from blood obtained from the heart of dead bison (40).
Treatment:
There are a number of drugs that have been used to treat babesiosis in cattle (9). Diminazene aceturate at 3mg/kg (41) and amicarbalide at 5 grams per adult bison cow (40) have been used successfully to treat babesiosis in bison.
Control:
There have been various protocols described for controlling babesiosis in cattle (9). These include vaccination, reducing the tick vector burden on cattle, and eradication of the tick vector (9). Natural infections of bison by Babesia species have not been reported in North America, so control programs for the prevention of babesiosis in bison have not been implemented.