STORRS Agricultural Experiment Station STORRS, CONNECTICUT INFECTIOUS ABORTION IN CATTLE SIXTH REPORT Methods of Conducting the Agglutination and The Bulletins of this Station are mailed free to citizens of Connecticut who apply for them, and to other applicants as far as the editions permit. Agricultural Economics. I. G. DAVIS, B.A., B.S., Economist. Animal Diseases. Chemistry. Dairy Husbandry. Economic Zoology. Poultry Husbandry. C. I. HENDRICKSON, M.S., Assistant Economist. LEO. F. RETTGER, PH.D., Bacteriologist. J. G. MCALPINE, PH.D., Assistant Bacteriologist. H. G. FISHER, B.A., Chemist. G. C. WHITE, A.M., Dairy Husbandman. R. E. JOHNSON, M.S., Assistant Dairy Husbandman. G. H. LAMSON, JR., M.S., Zoologist. A. F. SCHULZE, M.S., Assistant Zoologist. WM. F. KIRKPATRICK, B. Agr., B.E., Poultry Husbandman. MARGARET SCHNEIDER, A.B., Statistician. WALTER LANDAUER, PH.D., Assistant Geneticist. THE TUTTLE, MOREHOUSE & TAYLOR COMPANY, NEW HAVEN, CONN. SIXTH REPORT METHODS OF CONDUCTING THE AGGLUTINATION AND COMPLEMENT FIXATION TESTS, AND THEIR DIAGNOSTIC VALUE LEO F. RETTGER JAS. G. MCALPINE GEO. C. WHITE Progress in the scientific study of infectious abortion has, since the classical work of Bang (1897), been extremely slow, particularly as regards modes of transmission and methods of prevention. However, with the renewed activity in this field that is manifested in so many different laboratories, it must appear to the thoughtful student that the time is not far distant when some comprehensive and concerted plan of eradication of the disease can and will be put into operation which will be thoroughly practical and effective. It has already been demonstrated that herds can be established and maintained which are free from Bacterium abortus infection, though as yet on a relatively small scale. In view of the fact that all calves which have been born at full term remain or become non-reactors to the Bact. abortus serological tests by the time they are six months of age, no matter whether their dams were infected or not (Rettger and White, 1918), and that to become reactors they must become infected from without, negative, Bang abortion-free herds may be established by the removal of calves from all contact with infected animals and by permanent segregation of negative animals and the use of a herd sire whose services are confined to the given free herd. Furthermore, it now appears beyond all doubt that negative herds may be established by the removal of negative animals from herds in which Bang bacillus infection exists and by the segregation and safeguarding of such animals. Such free herds can be increased rapidly in size by the addition of sound calves. The above plans involve the execution of extreme measures in dairy management similar to those required in the complete eradication of tuberculosis from dairy herds. But before such projects can be put into effect, there must be general agreement on the choice and use of one or more methods of diagnosis. Indeed, identification of Bact. abortus infection is the foundation upon which such a system rests. *The term "Infectious Abortion" is used here in the more limited sense and as synonymous with "Bang Abortion Disease" of some other authors. Such calves need not, however, be separated from their dams and from other calves until they are from five to six months of age. Of all the methods thus far employed, namely, the cultural isolation, guinea-pig isolation, abortin, precipitin, and the agglutination and fixation methods, the two last-named alone have proven to be practical and acceptable. As infected cows do not always abort or continue to abort, the act of premature calving cannot be regarded as a dependable symptom or method of diagnosis. It should be said too that not all abortions are due to Bact. abortus infection. White, Rettger and McAlpine (1924) reported, after several years of observation, that 26 calvings out of each 100 reacting cows were abortions and that less than 3% of non-reacting cows calved prematurely. THE AGGLUTINATION AND COMPLEMENT FIXATION TESTS These methods are still the subject of considerable controversy, especially among students of veterinary medicine. However, there is no doubt that much of the incredulity and opposition that existed toward them as dependable and practical methods of diagnosis only a few years ago has in a large measure disappeared. It is the purpose of this bulletin to give a full description of the methods as they are now being employed in the writers' routine diagnosis and investigations, and to attempt to establish these tests on a still more permanent footing, by presenting systematic data showing agreement of the agglutination and fixation tests with each other, and of tests made at different times upon sera from the same animals. Also to point out a close correlation between these tests and acts of abortion. A brief historical review will not be out of place here. Grinsted (1909), while working in Bang's laboratory, was probably the first to employ the agglutination test in the diagnosis of infectious abortion. Holth (1909) obtained encouraging results with the agglutination method. Wall (1911) examined over 1000 animals, under Holth's direction, by both the agglutination and complement fixation methods and found close agreement between the results of the two tests. Brül (1911) claimed that of the two the complement fixation test is of the greater practical importance. McFadyean and Stockman (1912) reported favorably on the agglutination reaction. Zwick and Zoller (1913) concluded that the combined use of the two tests constituted a satisfactory method of diagnosis. Surface (1912) made a comparative study of the agglutination and fixation methods and pronounced them reliable. He states: "The logical course appears to demand the use of both these methods and to regard a cow as certainly infected when both tests show positive reactions." His report was accompanied with a full description of the fixation test as he employed it. Larson (1912) and Hadley and Beach (1912) employed practically the same technique as Surface. They regarded the complement fixation test as a reliable means of diagnosis. |