1956 Onderstepoort Journal of Veterinary Research, Volume 27, Number 1 & 2, 1956
Permanent URI for this collectionhttp://hdl.handle.net/2263/58035
Contentes Pages: Onderstepoort Journal of Veterinary Research, Vol ??, 19??
Browse
Recent Submissions
Now showing 1 - 18 of 18
Item Alterations in the blood sugar and ketone levels caused by dosing acetate, propionate and butyrate into the rumen of the sheep(Published by The Government Printer, Pretoria, 1956) Clark, R.; Malan, J.R.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Solutions of acetate, propionate and butyrate, alone and in combinations, were dosed into the rumen of sheep and the effects on blood sugar and ketones determined. Acetate was found to cause a slight and delayed rise in ketone bodies without affecting the blood sugar. Propionate caused a marked rise in blood sugar and bad a strong antiketogenic effect when given with butyrate. Butyrate produced a sharp rise in ketones, mainly beta-hydroxybutyric acid, together with a fall in blood sugar. The latter effect, however, was not constant. The intravenous injection of beta-hydroxybutyric acid appeared to reduce the blood sugar level. Aceto-acetic acid injected intravenously was partially converted to betahydroxybutyric acid. These results are discussed in relation to the more recent literature.Item Ticks in the South African Zoological Survey Collection. Part VIII. Two East African ticks(Published by The Government Printer, Pretoria, 1956) Theiler, Gertrud; Walker, J.B.; Wiley, A.J.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.(1) The description of the male and the female is given; the immature stages are described for the first time, the description is based on material raised by Miss Walker at Kabete. (2) The known hosts and its geographical distribution are given.Item The protection of sheep against blowfly strike. IV. An evaluation of certain organic phosphorus compounds(Published by The Government Printer, Pretoria, 1956) Fiedler, O.G.H.; Du Toit, R.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.An evaluation of the phosphorus insecticides by means of the bio-assay method has revealed that certain of these compounds combine very good larvicidal action with outstanding diffusing power in the fleece of living sheep. They compare favourably in this respect with the insecticides previously tested (Du Toit and Fiedler, 1953), the best of which was Aldrin with an average period of protection of 39 weeks. Dieldrin gave a protection of 37 weeks, and gamma B.H.C. 33 weeks. In addition to the properties mentioned, however, on which the duration of protection depends such compounds must comply with other demands necessitated by the environmental factors encountered on the bodies of sheep. To start with such protecting agents must not stain or damage the wool fibres and secondly they should be stable in a slightly alkaline medium in order to produce the maximum residual effect in all situations such as even in the soiled wool of the crutch region. From this point of view Parathion and EPN 300 must be excluded for practical purposes as they discolour the treated wool imparting to it a strong yellow-green tint Furthermore, their general use cannot be recommended on account of their toxicity to warm-blooded animals. The only phosphorus insecticide which seems to comply with all the requirements of a protecting agent for sheep against blowfly strike is Diazinon. Its larvicidal action as well as its diffusing power in the fleece are superior to insecticides like Dieldrin and B.H.C. which have proved to be very efficient protecting agents in practice. In the light of the properties studied Diazinon may be expected to produce a longer period of protection than B.H.C., which is not stable in an alkaline medium; and it may be found even to surpass Dieldrin in this field of application. Field experiments to demonstrate the actual period of protection of Diazinon in comparison with Dieldrin and B.H.C. are well under way in some of the worst blowfly areas of the Karoo and will be reported on in due course.Item A new method of treatment for sheep infested with the larvae of the sheep nasal-fly, Oestrus ovis. L. in the Union of South Africa(Published by The Government Printer, Pretoria, 1956) Du Toit, R.; Fiedler, O.G.H.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Item New species of sucking lice from South African game(Published by The Government Printer, Pretoria, 1956) Fiedler, O.G.H.; Stampa, S.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.During the course of a study on Anoplura material in the Onderstepoort collection, several specimens of the genus Linognathus were found which seemed to be incorrectly classified. A comparison with the respective types confirmed the suspicion and showed that these forms represent five distinct and so far undescribed species. Furthermore, a new species of Haematopinus collected recently off Eland, is also described in this paper. The types of all six new species are in the Onderstepoort collection.Item Canine distemper-immunization with avianised virus(Published by The Government Printer, Pretoria, 1956) Haig, D.A.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. In a brief review of the literature, methods which have been advocated for the immunisation of dogs against distemper and possible reasons for failures in immunity are discussed. 2. The propagation of Green's distemperoid virus in developing chick embryos is described. Conditions found most favourable for multiplication, were injection of eight-day-old embryos by the chorio-allantoic membrane route and incubation at 35° C. An inoculum with a high virus titre was most satisfactory for maintaining the derived Onderstepoort strain in embryonated eggs. 3. Continued serial passage of the Onderstepoort virus in developing chick embryos, resulted in a loss of contagiousness for ferrets by the 25th passage. 4. By the 130th egg-passage the degree of attenuation was such that the Onderstepoort virus could safely be used for the immunisation of both dogs and ferrets. 5. Immunity tests in ferrets and dogs vaccinated with the Onderstepoort virus, showed close immunological similarity between this strain and those obtained from encephalitic forms of distemper. 6. The keeping qualities of the Onderstepoort virus were examined. (a) Macerated infected chorio-allantoic membranes showed considerable decrease in potency after storage at 32°C. for 24 hours, and possibly complete loss after 48 hours. (b) Freeze-dried preparations of infected membranes showed very little loss of potency after storage at 37°C. for seven days provided buffered lactose-peptone solution was employed for making suspensions prior to freeze-drying. (c) Freeze-dried preparations retained potency for at least 81 days when stored at -15° C. 7. Titration of viral activity made in eggs, ferrets and dogs indicated that approximately 500 egg infective doses are required for the immunisation of both ferrets and dogs. 8. Immunisation of dogs with Onderstepoort virus has been undertaken on a large scale and to date approximately 40,000 doses of vaccine have been used in Southern Africa. The results have proved satisfactory. 9. It has become apparent that some artificially or naturally immunised dogs are liable to develop the encephalitic form of distemper. As the pathogenesis of this clinical manifestation is obscure, the necessity for determining the significance of the duration of immunity, the neurotropic affinities of various virus strains, concurrent infections and the general state of health of dogs prior to infection, is stressed.Item A discussion on the classification of the Theileridae(Pretoria : The Government Printer, 1956) Neitz, W.O.; Jansen, B.C.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.The morphological similarity between the members of the genera Theileria and Gonderia in domestic animals makes their differentiation extremely difficult. In making a differential diagnosis veterinarians and zoologists often are compelled to take the pathogenicity and the epizootology into consideration. In doubtful cases it may even be necessary to resort to in vivo cross-immunity tests before a final identification can be made. From this it becomes evident that a great deal of work will have to be done before the "intermediate stages" of the Theileria spp. referred to by Du Toit (1930) can be identified. From the observations on the artificial transmission of East Coast fever (Theiler, 1912; Theiler and Du Toit, 1929) and of Tzaneen disease (Gonderia mutans infection) (De Kock, Van Heerden, Du Toit and Neitz, 1937) it becomes apparent that the infectious agents cannot be maintained by serial passages as has been possible in the case of Gonderia annulata (Sergent, Donatien, Parrot and Lestoquard, 1945). The opinion is expressed that the undetermined species referred to by Du Toit (1930) may behave in a similar way. For systematic studies, therefore, it will be necessary to determine the vectors of these parasites. From this it is obvious that many years will elapse before the classification of this group of micro-organisms can be placed on a permanent basis.Item The experimental transmission of Theileria ovis by Rhipicephalus evertsi(Published by The Government Printer, Pretoria, 1956) Jansen, B.C.; Neitz, W.O.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. The transmission of Th. ovis by the two host tick Rh. evertsi was successful in six susceptible splenectomized sheep. 2. Th. ovis was picked up by the larvae and nymphae and transmitted by the ensuing adults. 3. Koch's bodies were demonstrated in rare numbers in the parotid lymphatic glands of four sheep. 4. The reaction in all the sheep was accompanied by an increased lymphocyte production in the parotid lymphatic glands, a fever and a relatively mild anaemia. 5. These results once more confirm the observations of Lestoquard (1929) that Koch's bodies form a part of the Th. ovis life-cycle.Item Zoological Survey of the Union of South Africa. Tick survey. Part IX. The distribution of the three South African Hyalommas or bontpoots(Published by The Government Printer, Pretoria, 1956) Theiler, Gertrud; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.SUMMARY 1: 1. The distribution of H. truncatum (syn. H. transiens) is given in terms of political divisions. 2. The limiting factor to its distribution is seen to be increasing humidity. It is present up to 20 inches per annum. Above this the conditions are marginal and the presence of the tick is dependent on more localized climatic variations and micro-habitats. Where the high rainfall is due to heavy thunderstorms the tick can maintain itself precariously; where the high rainfall is due to a more even distribution in time the tick is unable to exist at the higher rainfall levels. In the Cape Midlands, with a low rainfall, the ticks tend to be absent from mountain farms having snow in winter. 3. Neither dipping nor vegetation types play a limiting role. 4. H. truncatum is shown to occur in all the drier areas throughout Africa, South of the Sahara. SUMMARY 2: 1. The distribution of H. rufipes is given in terms of political divisions. 2. The limiting factor to its distribution in South Africa is seen to be increasing humidity. It is present in areas up to 20 to 25 inches per annum. Above this it can maintain itself in areas with up to 30 inches per annum, where the atmosphere is dry; but in moist semi-tropical areas at 25 to 30 inches it is either absent or but precariously established. Also in dry areas it is not able to maintain itself in winter rainfall areas or in areas with winter snow. 3. Neither dipping nor vegetation types play a limiting role. 4. Data for central Africa are meagre, but its distribution is possibly limited not only to the lower rainfall regions but possibly also to areas with but one rainy season per annum. SUMMARY 3: 1. The distribution of H. glabrum is given in terms of political divisions and is seen to be confined to a very restricted area of South Africa. 2. The limiting factor is seen to be a humidity / vegetational one. It is tied to Karoo, which itself is limited by humidity /aridity. Ten to twelve inches rainfall seems to be the critical range; in a few areas it is present at 15 inches, possibly areas with long intervening droughts. It can exist in marginal vegetational Karooid areas, provided these areas have a low a:nnual rainfall; at higher rainfalls it does not exist in marginal vegetation areas. 3. For record purposes, since we are not quite convinced that H. glabrum is synonymous with H. turanicum, it has been decided to retain Delpy's name.Item Studies on tuberculosis in dogs, and on a case of human tuberculosis contracted from a dog(Published by The Government Printer, Pretoria, 1956) De Kock, G.; Le Roux, J.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. Apparently this is the first case on record in which tuberculosis of the skin in man was contracted from an infected dog through a wound. The infection probably occurred when handling the heavily infected lymph nodes and serous membranes of dog No. I at post-mortem. 2. In view of the rather obscure nature of the lesions, and the fact that this case was complicated with nervous distemper, tuberculosis was not suspected in this dog, until diagnosed histologically. 3. The nodule on the finger, which remained completely circumscribed, was successfully excised approximately three months after infection. 4. In the two dogs with natural tuberculosis the infection was of the nature of an incomplete primary complex in the abdominal cavity. 5. Although large doses of tubercle bacilli were injected into two; dogs intravenously, the disease was much milder, and less widespread than in the two natural cases. 6. In all the dogs clusters of macrophages and epithelioids dominated the picture in the lesions, whereas neutrophiles appeared to play an insignificant part. There was no evidence of Langhans giant cells and calcification, and in the liver, spleen and lungs no caseation was observed. 7. In view of the morphology of the tubercle bacilli, the nature of their growth in culture media, and of their behaviour in rabbits, it was concluded that the human type of organism was involved in all these cases.Item Strain 19 Brucella vaccine. II. The preparation of freeze-dried live vaccine(Published by The Government Printer, Pretoria, 1956) Van Drimmelen, G.C.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.A freeze-dried Brucella vaccine has been developed which can be issued with all the usual guarantees, e.g. 60 x 10⁹ viable organisms per dose viable for an extended period. This vaccine has been prepared in concentrated form which makes it possible to reconstitute the contents of one ampoule into a number of doses. Such a vaccine is eminently suitable for use in Southern Africa especially in the more remote areas. Concentration by means of carboxy-methyl-cellulose of the organisms grown in aerated liquid culture increased the dosage per ampoule and the survival rate after freeze-drying and during storage.Item Strain 19 Brucella vaccine. I. Production of vaccine by the shake flask technique(Published by The Government Printer, Pretoria, 1956) Van Drimmelen, G.C.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.A method for the production of Brucella abortus Strain 19 Vaccine by a shake flask, aerated liquid culture technique is described.Item Studies on the aetiology of sweating sickness(Published by The Government Printer, Pretoria, 1956) Neitz, W.O.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. An account is given of a series of experiments on calves and pigs on which infective Hyalomma transiens were allowed to feed for periods of variable duration. 2. It was determined that the causal agent can be transmitted by the vector as early as 72 hours, but usually between 72 and 96 hours after attachment. 3. Tick-feeding periods of three, four or five days are followed by either inapparent infections relatively mild or severe reactions and recovery. 4. Tick-feeding periods of six days and longer are followed by severe or very severe reactions terminating fatally in 75 per cent of cases. 5. The behaviour of the causal agent of sweating sickness does not conform to that observed in arthropod-borne viruses. 6. It is suggested that the causal agent is a "toxin" generated by adult ticks during the process of feeding. 7. Possible prophylactic measures based on control of the infective tick are discussed.Item Wesselsbron virus - a virus not previously described, associated with abortion in domestic animals(Published by The Government Printer, Pretoria, 1956) Weiss, K.E.; Haig, D.A.; Alexander, R.A.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. There has been isolated from a lamb a pantropic virus with neurotropic properties and a well-marked affinity for embryonic tissue. 2. In the field the vectors are mosquitoes which have yet to be identified accurately. 3. In sheep infection with the virus causes a febrile reaction after a short incubation period of about one to four days, the mortality rate not being high. Pregnant ewes may abort during the febrile reaction in which case virus could not be isolated from the foetuses. Subsequently the virus invades the foetus causing death usually with abortion. The mortality amongst foetuses carried to full term and new-born lambs is very high (practically 100%). New born lambs suckling reacting ewes did not become infected by contact with the reacting ewe. 4. In addition to sheep, cattle, horses, pigs, mice, rabbits, guinea-pigs and man are susceptible. 5. Infant and adult mice are equally susceptible to intracerebral inoculation, the mortality being 100%. Infant mice are fully susceptible to intraperitoneal infection but in adult mice the reaction is at most inapparent.Item The use of tissue culture propagated bluetongue virus for complement fixation studies on sheep sera(Published by The Government Printer, Pretoria, 1956) Shone, D.K.; Haig, D.A.; McKercher, D.G.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.The development of a complement-fixation test possessing broad specificity, in which tissue culture propagated virus is used as antigen, for studies on bluetongue in sheep is described.Item The cytopathogenic action of bluetongue virus on tissue cultures and its application to the detection of antibodies in the serum of sheep(Published by The Government Printer, Pretoria, 1956) Haig, D.A.; McKercher, D.G.; Alexander, R.A.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Cytopathogenic activity by egg adapted strains of bluetongue virus for sheep kidney cells in culture, and the neutralization of this activity by homologous antiserum are described. The possible applications of this phenomenon to studies on various phases of bluetongue is discussed briefly. Reference is made to preliminary studies which indicate that the property of cytopathogenesis is not associated with virulent, unmodified, bluetongue virus.Item Complement fixation with horsesickness viruses(Published by The Government Printer, Pretoria, 1956) McIntosh, B.M.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Fixation of complement bas been obtained using antigens prepared from suckling mouse brains and antisera from hyperimmune guinea-pigs. With horsesickness viruses the complement fixation test is less type specific than the neutralization test and no antigenic differentiation between the seven heterotypic strains tested was possible. The value of the complement fixation test in the diagnosis of the disease is discussed.Item A consolidation of our knowledge of the transmission of tick-borne diseases(Published by The Government Printer, Pretoria, 1956) Neitz, W.O.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.(1) Ticks concerned in the transmission of Babesia spp., Aegyptianella sp., Theileria sp., Gonderia spp., Anaplasma spp., Borrelia spp., viruses and "toxins" responsible for diseases in livestock have been enumerated. (2) This information is presented in a series of tables. (3) An attempt has been made to determine the correct names of various ticks. (4) The vectors of Babesia major, B. taylori, B. foliata, B. perroncitoi, B. felis and Gonderia hirci need to be determined. (5) In all diseases stage to stage transmission within the same generation has been established in one or more of the transmitters, except in those concerned with the transmission of tick paralysis and sweating sickness. (6) Transovarial transmission has been established in one or more of the vectors except in those concerned with the transmission of Theileria parva, Gonderia mutans, G. lawrencei, G. ovis, Rickettsia ruminantium, R. bovis, R. ovina, tick-borne fever, louping ill, Czecho-Slovakian tick encephalitis and Kisenyi sheep disease. (7) From this it is deduced that ticks do not only act as vectors but that they can also serve as reservoirs of certain infectious agents. (8) Vectors, other than ticks, which are capable of transmitting the western type of equine encephalomyelitis, St. Louis encephalitis and Borrelia anserina are referred to in the text. (9) Attention has been drawn to the fact that potential vectors of certain diseases (canine biliary fever, heartwater, louping ill, Nairobi and Kisenyi sheep diseases) do occur beyond the boundaries of the known enzootic areas. The danger associated with the introduction of affected animals into such regions is self-evident.