Chemotherapeutic efficacy of Imidocarb dihydrochloride on concurrent bovine anaplasmosis and babesiasis

EIGHTEEN MALE HOLSTEIN-FRIESIAN CALVES 300 DAYS OLD WERE FIRST TESTED TO ESTABLISH THAT THEY WERE NOT INFECTED BY ANAPLASMOSIS OR BABESIOSIS. THEY WERE THEN INJECTED WITH 1.0, 2.0, OR 2.5 MG/KG OF IMIDOCARB DIHYDROCHLORIDE AS WELL AS 5 ML OF BLOOD CONTAINING 2 X 109 PER CM3 OF ANAPLASMA MARGINALE. ALSO INJECTED WERE SIMILAR QUANTITIES OF TWO OTHER PARASITIC ORGANISMS, BABESIA BIGEMINA AND B. ARGENTINA. THE DOSAGES OF 2.0 AND 2.5 MG/KG OF THE DRUG RAPIDLY INHIBITED ACUTE ASCENDING CONCURRENT PARASITAEMIAS OF A. MARGINALE, B. BIGEMINA, AND B. ARGENTINA. HOWEVER, 1.0 MG/KG HAD A MINIMAL EFFECT ON A. MARGINALE, THOUGH IT WAS VERY EFFECTIVE AGAINST THE OTHER TWO ORGANISMS. ALL THREE DOSE LEVELS OF THE DRUG INHIBITED THE DEVELOPMENT OF IMMUNITY OF THE ACUTE BABESIA SPP. INFECTIONS, MAKING THE CALVES MORE SUSCEPTIBLE TO BABESIOSIS UPON CHALLENGE. THE INHIBITION OF A. MARGINALE PARASITAEMIAS WAS DIRECTLY RELATED TO INCREASING DOSES OF IMIDOCARB DIHYDROCHLORIDE. HOWEVER, RECRUDESCING AND PERSISTING POST-TREATMENT PARASITAEMIAS ALSO OCCURRED MORE FREQUENTLY AT HIGHER DOSES.