Acute anaplasmosis in imported cattle.

Of 18 Hereford cattle imported into Quebec from the eastern U.S.A., five exhibited acute hemolytic anemia, icterus, depression, fever, anorexia and died; 11 were killed because they had positive or suspicious anaplasma titers and two were quarantined. Anaplasma marginale organisms were found in the erythrocytes of the sick animals by light and electron microscopy. The partial absence of erythrocytic plasmalemma on several electron photomicrographs suggested exit of the anaplasma bodies. Titers up to 1:320 in infected animals were found by the complement fixation test.