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Control of Swine Fever by Immunisation
SWINE FEVER
375
Control of Swine Fever by Immunisation. By M. DORSET, Chief, Biochemic Division , U.S. Bureau of A nimal In dustry, Wa shington, D.C ., U.S .A . From these facts but one conclusion can be drawn , viz. that the widespread use of the simultaneous inoculation in the United States has been accompanied by decreased prevalence of swine fever.
Conclusions. From the foregoing we may offer the following conclusion s : (1) Immunisation offers the most practicable and effective means of controlling losses from swine fever. (2) Governmental in spection of serum producing establishments is of prime importance. (3) Th e serum alone method is to be used in infected premises if the virus infection is complicated with bacterial infection (salmonella, past eurella, erysipelas) . (4) The simultan eous inoculation is to be preferred in healthy herds in exposed districts. H ere an excess of serum must be used. (5) Immunisation should be performed only by skilled veterinarians. Summary.
The author discusses the control of swine fever by the " Slaughterout " method , the sanitary police method , and hy immunisation. In addition, th ere are considered Government control of the production of swine fever immune serum and virus, the administration of serum alone and of the simultaneous inoculation, the application of serum in healthy herds, in exposed herds, and in infect ed herds. Th ere is a general discussion of the effect of widespread use of the simultaneous inoculation upon the prevalence of swine fever in the United States. The following conclusions are submitted : (1) Immunisation offers the most practicable and effective mean s of controlling losses from swine fever. (2) Governmental inspection of serum producing establishments is of prime importance. (3) 'f.he serum alone method is to be used in infected premises if the virus infection is complicated with bacterial infection (salmonella, pasteurella, erysipelas).
376
THE VETEE.l NAR Y. JOUR NAL (4) The simulta neous in oculat ion is to be p refer red in healthy herds in exposed distric ts. H ere an excess of seru m m ust be used. (5) Immunisa tion should be perfo rmed on ly b y skilled veterina ria ns.
Infectious Abortion of CattJe, Sheep and Swine. By PROF. H. HOL TH, Director of T he S tate Veterinary I nst£tute, Oslo. Summary. · Th e a uthor deals briefl y wi th the va rious causes o f infec tious a borti on and reports a number of ex periments made by him which s how the rela tion between the number of sporadic a bort ions a nd cases of abortion produced by a bortion bacilli . Thus at t he Veterina ry Institute there were in ve'itigated in th e pe riod 1912- 1929 material f ~·o m 16,743 cows which had a borted , of which 28·72% reac ted more or less distinctly. The cows in quest ion were distri buted amongst 12,905 h erds, of which 28·35 % were found to be infected or to be suspec ted . A short survey is given of th e m orph ology of th e abo rt ion bacillus a nd its biological conditions, a nd it is men tioned tha t a cowh ouse which h as bee n clea nsed a nd ha s rema ined emp t y d uring t he summer has been fo und by experience to be free f rom in fec tion . The occurrence of the a bortion b acillus in the a nimal' s organi sm is discussed in grea ter detail, a nd the frequency of the abortion b acilli in the milk is furthe r illustra ted . Th e writer in vest igated th e milk from 13 cows during a period of about one month after abortion had ta ken place, a nd was in a position to show a bortion bacilli in nine of th em. In a large stock 35 reacting cows we re in vestigated, of whi ch four gave a positive findin g of bacilli ; and in another of 65, 35 of whico pro ved t o have bacilli in their milk . This stock wa'i exam ined severa l times. On account of the mixing from many places of trade milk in Oslo it is compara tively free from a bortion bacilli. Thus of 106 sam ples from shops only one was found to conta in a bortion b acilli, whilst 241 samples of mixed milk from farm s gave a bortion bacilli in 44 cases. The writer emphasises the great importance of milk infection in the spread of the disease and its presence a mongst the various herds. In dealing with the diagnostic aids the a uthor sta tes tha t he considers the microsco pical ex amina tion not to be very relia ble, a nd he recommends as more exact m ethods the generally known a ntigen tes t or inj ec tion of ma teria l in
375
Control of Swine Fever by Immunisation. By M. DORSET, Chief, Biochemic Division , U.S. Bureau of A nimal In dustry, Wa shington, D.C ., U.S .A . From these facts but one conclusion can be drawn , viz. that the widespread use of the simultaneous inoculation in the United States has been accompanied by decreased prevalence of swine fever.
Conclusions. From the foregoing we may offer the following conclusion s : (1) Immunisation offers the most practicable and effective means of controlling losses from swine fever. (2) Governmental in spection of serum producing establishments is of prime importance. (3) Th e serum alone method is to be used in infected premises if the virus infection is complicated with bacterial infection (salmonella, past eurella, erysipelas) . (4) The simultan eous inoculation is to be preferred in healthy herds in exposed districts. H ere an excess of serum must be used. (5) Immunisation should be performed only by skilled veterinarians. Summary.
The author discusses the control of swine fever by the " Slaughterout " method , the sanitary police method , and hy immunisation. In addition, th ere are considered Government control of the production of swine fever immune serum and virus, the administration of serum alone and of the simultaneous inoculation, the application of serum in healthy herds, in exposed herds, and in infect ed herds. Th ere is a general discussion of the effect of widespread use of the simultaneous inoculation upon the prevalence of swine fever in the United States. The following conclusions are submitted : (1) Immunisation offers the most practicable and effective mean s of controlling losses from swine fever. (2) Governmental inspection of serum producing establishments is of prime importance. (3) 'f.he serum alone method is to be used in infected premises if the virus infection is complicated with bacterial infection (salmonella, pasteurella, erysipelas).
376
THE VETEE.l NAR Y. JOUR NAL (4) The simulta neous in oculat ion is to be p refer red in healthy herds in exposed distric ts. H ere an excess of seru m m ust be used. (5) Immunisa tion should be perfo rmed on ly b y skilled veterina ria ns.
Infectious Abortion of CattJe, Sheep and Swine. By PROF. H. HOL TH, Director of T he S tate Veterinary I nst£tute, Oslo. Summary. · Th e a uthor deals briefl y wi th the va rious causes o f infec tious a borti on and reports a number of ex periments made by him which s how the rela tion between the number of sporadic a bort ions a nd cases of abortion produced by a bortion bacilli . Thus at t he Veterina ry Institute there were in ve'itigated in th e pe riod 1912- 1929 material f ~·o m 16,743 cows which had a borted , of which 28·72% reac ted more or less distinctly. The cows in quest ion were distri buted amongst 12,905 h erds, of which 28·35 % were found to be infected or to be suspec ted . A short survey is given of th e m orph ology of th e abo rt ion bacillus a nd its biological conditions, a nd it is men tioned tha t a cowh ouse which h as bee n clea nsed a nd ha s rema ined emp t y d uring t he summer has been fo und by experience to be free f rom in fec tion . The occurrence of the a bortion b acillus in the a nimal' s organi sm is discussed in grea ter detail, a nd the frequency of the abortion b acilli in the milk is furthe r illustra ted . Th e writer in vest igated th e milk from 13 cows during a period of about one month after abortion had ta ken place, a nd was in a position to show a bortion bacilli in nine of th em. In a large stock 35 reacting cows we re in vestigated, of whi ch four gave a positive findin g of bacilli ; and in another of 65, 35 of whico pro ved t o have bacilli in their milk . This stock wa'i exam ined severa l times. On account of the mixing from many places of trade milk in Oslo it is compara tively free from a bortion bacilli. Thus of 106 sam ples from shops only one was found to conta in a bortion b acilli, whilst 241 samples of mixed milk from farm s gave a bortion bacilli in 44 cases. The writer emphasises the great importance of milk infection in the spread of the disease and its presence a mongst the various herds. In dealing with the diagnostic aids the a uthor sta tes tha t he considers the microsco pical ex amina tion not to be very relia ble, a nd he recommends as more exact m ethods the generally known a ntigen tes t or inj ec tion of ma teria l in