A Technique for Demonstration of Coccidiostatic Activity of Anticoccidial Agents

Abstract

A new combination of parameters used in anticoccidial evaluation has been combined in a graphic representation to separate from coccidio- cidal drug activity. The procedure involves plotting graphically daily oocyst counts and daily lesion scores while birds are on medication, during the period following artificial inoculation, and during a period following drug withdrawal 10 days post- infection. Coccidiostatic activity is indicated by peaks in lesion scores and oocyst production following drug withdrawal. Coccidiocidal activity is indicated by absence of peaks during the withdrawal period combined with suppression of oocysts and lesion scores compared to non-medicated controls during the primary infection. In action against Eimeria tenella drugs were classified as follows: strongly coccidio- static-buquinolate, clopidol, decoquinate, methyl benzoquate, and anticoccidial C; coccidiocidal-chlorotetracycline, oxytetracycline, sulfachloropyrazine, sulfa- dimethoxine, sulfamethazine, sulfaquinoxaline, Tri-sulfa-lyte?, and tylosin; both coc- cidiostatic and coccidiocidal-amprolium plus ethopabate, anticoccidial A, monen- sin, nicarbazin, Novastat?, Polystat', RofenaidTM Unistat?, Whitsyn?-S, and zoalene. Since the activity of sulfanilamide was first demonstrated (Levine, 1939), an extensive volume of information has been published compar- ing the efficacy of the numerous anticoccidial drugs. The manufacture of these products has become a major pharmaceutical industry. Their use in preventive medication has been almost universally adopted by the poultry industry and it is now difficult to purchase non-medicated starter feed in the USA. Prevention of these several closely related coccidial diseases has been a major factor in per- mitting development of the gigantic broiler industry (Reid, 1968). In all of this development, the term coccidiostatic has been used although it is generally recognized that many of the more than 20 pharmaceutical products commercially used are primarily coccidiocidal rather than in their activity. A more accurate term would be anticoccidial agent but the term coccidiostat is so widely adopted that a change seems unlikely. Within the past three years several new anticoccidial drugs have been made available which are much more truly in their activity than those ABSTRACT: A new combination of parameters used in anticoccidial evaluation has been combined in a graphic representation to separate from coccidio- cidal drug activity. The procedure involves plotting graphically daily oocyst counts and daily lesion scores while birds are on medication, during the period following artificial inoculation, and during a period following drug withdrawal 10 days post- infection. Coccidiostatic activity is indicated by peaks in lesion scores and oocyst production following drug withdrawal. Coccidiocidal activity is indicated by absence of peaks during the withdrawal period combined with suppression of oocysts and lesion scores compared to non-medicated controls during the primary infection. In action against Eimeria tenella drugs were classified as follows: strongly coccidio- static-buquinolate, clopidol, decoquinate, methyl benzoquate, and anticoccidial C; coccidiocidal-chlorotetracycline, oxytetracycline, sulfachloropyrazine, sulfa- dimethoxine, sulfamethazine, sulfaquinoxaline, Tri-sulfa-lyte?, and tylosin; both coc- cidiostatic and coccidiocidal-amprolium plus ethopabate, anticoccidial A, monen- sin, nicarbazin, Novastat?, Polystat', RofenaidTM Unistat?, Whitsyn?-S, and zoalene. Since the activity of sulfanilamide was first demonstrated (Levine, 1939), an extensive volume of information has been published compar- ing the efficacy of the numerous anticoccidial drugs. The manufacture of these products has become a major pharmaceutical industry. Their use in preventive medication has been almost universally adopted by the poultry industry and it is now difficult to purchase non-medicated starter feed in the USA. Prevention of these several closely related coccidial diseases has been a major factor in per- mitting development of the gigantic broiler industry (Reid, 1968). In all of this development, the term coccidiostatic has been used although it is generally recognized that many of the more than 20 pharmaceutical products commercially used are primarily coccidiocidal rather than in their activity. A more accurate term would be anticoccidial agent but the term coccidiostat is so widely adopted that a change seems unlikely. Within the past three years several new anticoccidial drugs have been made available which are much more truly in their activity than those