Pathology and prevention of Leucocytozoon smithi infection of turkeys

Leucocytozoon smithi caused a transient congestive pneumonia as a result of alveolar capillary blockage by mature gametocytes following completion of release of microgametocytes from the liver. Transient splenic enlargement through capillary blockage with hemosiderin accumulation and increased lymphocytic hyperplasia were noted. All other tissues studied exhibited transient evidence of increased lymphocytic hyperplasia and this was related to the level of parasitemia. Demonstrated in addition was an impairment of immunological responsiveness in turkeys during the period immediately following completion of hepatic schizogony. The commitment of macrophages and the impairment of circulation in the splenic red pulp because of parasitic congestion may have contributed to this state. Clopidol in feed at levels of 0.025% and 0.0125% effectively controlled L. smithi parasitemia.