Experimental bovine anaplasmosis: clinico-pathological and nutritional studies.

Groups of Brahman-cross steers maintained on two nutritional planes were infected intravenously with a stabilate of Anaplasma marginale. In general, animals on the higher plane of nutrition were more severely affected. Fever was the first clinical sign of anaplasmosis but, like anaemia, was absent in the mildest cases. When present anaemia appeared two to three weeks after infection. There was a corresponding increase in erythrocyte sedimentation rates when read after 24 h but not at 1 h. The haemolytic nature of the anaemia was indicated by a significant increase in unconjugated bilirubin during the acute phase. Some visceral damage was suggested by a significant increase of serum aspartate amino-transferase (GOT) especially in severely affected animals of the 'high' nutrition group but no significant change occurred in levels of alanine amino-transferase (GPT).