Observations on erythrocytic acetylcholinesterase activity in experimentally induced anaplasmosis in calves.

Erythrocytic acetylcholinesterase (AChE) activity was assessed in splenectomized bovine calves inoculated with Anaplasma marginale. Other parameters, i.e., haematological values (haemoglobin, packed-cell volume, and total erythrocytic count), percentage parasitaemia and the ensuing host reactions during Anaplasma infection were also studied in relation to AChE activity. There was significant inhibition of red blood cell-AChE activity commencing soon after inoculation of infected blood; this preceded a substantial decrease in haematological values along with high parasitaemia. The changes in AChE activity may possibly be associated with increased cell membrane permeability, thus triggering the entry of A. marginale organisms into red blood cells.