1954 Onderstepoort Journal of Veterinary Research, Volume 26, Number 3 & 4, 1954
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Item Studies on the histopathology and pathogenesis of Newcastle disease of fowls in South Africa, with special reference to the lymphoid tissue. A preliminary report.(Published by The Government Printer, Pretoria, 1954) De Kock, G.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. Newcastle Disease, after intramuscular inoculation of virulent virus, was characterised by pathognomonic lesions in the spleen, the gastro-intestinal tract, and the nervous system. 2. In the Spleen degenerative changes in the cells of the lymphoid sheath were noted in early deaths. In some of them flake-like granules were observed. There were depletion of lymphocytic cells in the follicle, increase in the number of plasmacytes, and proliferation of reticulum cells. In cases with a more protracted course, hyperplasia of the lymphoid tissue was apparent. 3. In the gastro-intestinal tract the chief changes were observed in the Proventriculus, the Small Intestine, and Caecal Tonsils. In early cases, this was of the nature of a localised necrosis with haemorrhage. The changes in the lymphoid tissue were of a similar nature as those observed in the spleen. 4. The Nervous system in the majority of cases revealed a hyperaemia, and in some, small haemorrhages. The changes in the small blood vessels were of the nature of a so-called "endotheliosis" with an infiltration of the walls with lymphocytes, and other cells of the blood. In some of these vessels the presence of plasma, mononuclears and red cells was noted within the lumen. In some cases chromatolysis and slight gliosis were seen. 5. More information is desired about the depots, morphology, and function of the lymphoid tissue of the fowl. It would, however, appear that lymphocytes and plasmacytes have an independent origin, and that they are probably implicated in the propagation of the virus and antibody mechanism. At this stage it is not possible to indicate what the nature is of the flake-like granules in some of the cells of the lymphoid tissue. Further investigations are indicated to clarify some of the problems raised in this preliminary study.Item The identity of so-called Paramphistomum cervi and P. explanatum, two common species of ruminant trematodes in South Africa(Published by The Government Printer, Pretoria, 1954) Swart, P.J.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Item Tick survey. VIII. Checklists of ticks recorded from the Belgian Congo and Ruanda Urundi, from Angola, and from Northern Rhodesia(Published by The Government Printer, Pretoria, 1954) Theiler, Gertrud; Robinson, Britha N.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.I. The ticks from the Belgian Congo have been listed, and the commoner species plotted on a vegetation map. II. An attempt has been made to analyse the distribution of the commoner species which play an economic role in the Belgian Congo.Item The effect of Lindane vapour on stored product insects(Published by The Government Printer, Pretoria, 1954) Fiedler, O.G.H.; Du Toit, R.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.To assess the insecticidal effect of vapour originating from small quantities of Lindane at a temperature of 25°C. (77° F.) twelve series of experiments were conducted in which stored product insects in closed fumigation chambers were subjected to the vapour from decreasing dosages of Lindane deposits (200-5 mg. per cub. ft.). The correctly measured quantity of the insecticide evenly distributed on surfaces of equal size was achieved by impregnating sheets of paper with a Lindane solution of desired strengths. The following insect species were included in the tests: - Triboleum confusum Duval, Sitophilus (Calandra) granaria L., Rhizopertha dominica F., Acheta bimaculata de G., Dermestes vulpinus F. larvae, and Tineola bisselliella Hummel larvae. The susceptibility of the different insect species varied considerably, but vapour originating from 5 mg. Lindane in one cubic foot of air was sufficiently toxic to produce a complete kill or high mortality after several days of exposure. The period until death supervenes does not correspond with the dosage applied. The mortality rate is dependent rather on the length of exposure. This principle is recommended for long term protection of stored products and for the control of insect pests in enclosed spaces.Item A new African lousefly, Raymondia hardyi sp. n. (Streblidae, Pupipara)(Published by The Government Printer, Pretoria, 1954) Fiedler, O.G.H.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Item The protection of sheep against blowfly strike. III. The effect of different formulations of gamma benzene hexachloride (B.H.C.)(Published by The Government Printer, Pretoria, 1954) Fiedler, O.G.H.; Du Toit, R.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. Three groups each of twelve merino sheep were treated separately with Lindane in emulsion, suspension and dust form to determine the influence of the formulation on the duration of protection against blowfly strike. 2. The emulsion and suspension contained a wetting agent of anionic type. The emulsion, containing 970 p.p.m. gamma B.H.C. and the suspension with 940 p.p.m. gamma B.H.C. were applied by immersion in a small vat of 120 gallons (546 litres) capacity. Twelve sheep were used for each formulation. The removal of dip wash per animal and the depletion rate of the insecticide were determined. 3. The rate of depletion of insecticide from the dipping bath was higher per sheep treated in the emulsion than in the suspension. This is supported by the finding that the average deposition of Lindane per sheep was 30•6 grams for the emulsion, but only 16•9 grams after immersion in the suspension. 4. The percentage rate of exhaustion of insecticide continued to rise progressively as the absolute quantity available in the tank decreased. This rise in percentage depletion was far more marked in the case of the emulsion that the suspension. 5. There was no significant difference between the amount of insecticide deposited in the fleece of the first and last of twelve sheep treated in either the emulsion or the suspension formulation. This may be ascribed to the finding that in the case of the emulsion the progressively higher percentage depletion accounted for the higher rate of deposition in the wool, in other words the higher rate of selective removal. In the case of the suspension the lower absolute depletion rate together with the appreciably lower percentage removal were the factors involved in maintaining the even deposition of insecticide with the progress of dipping. Had more sheep been dipped the end result would probably be different. 6. Continued immersion of sheep in an emulsion dip will result in a sudden and rapid complete depletion of insecticide below the level of biological effectiveness. Using a suspension dip it will take longer to reach this point. 7. Using a non-returnable spray as the means of applying an insecticide a suspension spray must be mixed at 2 ½ times the concentration of a dip and an emulsion of anionic type at about 5 times the concentration of a dip to obtain the same concentration of insecticide on treated sheep. 8. Attention is directed to Laudani's observation that the amount of insecticide absorbed by wool is dependent not only on the concentration of the active ingredient in the dip wash but also on the absolute amount present. Full consideration must therefore be paid to the capacity of a dip or bath. 9. The third group of animals was treated with dust at a rate of 17 gm. of the active ingredient per head, i.e. the amount absorbed by each sheep dipped in the suspension, in order to facilitate comparison of larvicidal efficacy of a dust and a suspension. The bio-assay tests with first instar maggots of Lucilia cuprina revealed an average protection of relatively shorter duration, 29•4 weeks with the considerably heavier deposit (30•6 gm.) in the case of emulsion, than the 27•4 weeks with the suspension (16 • 9 gm.) and 29 • 8 weeks for the dust (17 gm.). The dust, therefore, gave the best protection of the three formulations per unit of insecticide absorbed by the fleece. 10. The grease content of the fleece was shown to exert a marked influence on the degree of efficacy of the insecticide deposited from an emulsion. This does not apply, however, in the case of the dust or the suspension. The loss of larvicidal activity is proportionate to the level of wool grease which is not affected by dipping or spraying. 11. The quality of the wool has no effect on the protecting properties of any of the formulations. 12. The use of B.H.C. or any compound possessing good powers of diffusion in the wool is recommended for the long term protection of woolled sheep against blowfly strike. Such compounds may be used in the form of dusts or wettable powders but the present investigation suggests that their use as emulsions is contraindicated.Item The protection of sheep against blowfly strike. II. The influence of the length of wool at the time of treatment on the duration of protection(Published by The Government Printer, Pretoria, 1954) Du Toit, R.; Fiedler, O.G.H.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.The duration of protection afforded to sheep against blowfly strike by the treatment of the wool with an insecticide possessing good powers of diffusion is correlated with the length of wool at the time of treatment. For every additional 1/4 inch in the length of fleece treated by B.H.C. wettable powder at a concentration of 0•5 per cent gamma, full protection is prolonged by 2 ½ weeks and partial protection by 6 weeks.Item The parasites of tsetse flies in Zululand with special reference to the influence of the hosts upon them(Published by The Government Printer, Pretoria, 1954) Fiedler, O.G.H.; Kluge, E.B.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Item The influence of the tsetse fly eradication campaign on the breeding activity of Glossinae and their parasites in Zululand(Published by The Government Printer, Pretoria, 1954) Fiedler, O.G.H.; Du Toit, R.; Kluge, E.B.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.During the course of the tsetse fly eradication campaign in northern Zululand, where the new contact insecticides D.D.T. and benzene hexachloride (B.H.C.) have been used on an extensive scale for the first time in the history of Nagana control, a study was conducted concurrently over a period of two years (March 1947 to March 1949) of the effect of these insecticides upon the parasites of tsetse flies.Item Trypanosomiasis in Zululand and the control of tsetse flies by chemical means(Published by The Government Printer, Pretoria, 1954) Du Toit, R.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. The distribution of Nagana and its importance as a limiting factor in the development of the livestock industry in Africa are stressed. 2. The relationship between the tsetse fly belt within the Union of South Africa and those occurring in Portuguese East Africa is discussed, emphasis being laid upon the isolation of Glossina pallidipes in the Union. 3. Within Zululand the range of dispersion of G. pallidipes, G. brevipalpis and G. austeni, occupying approximately 7,000 square miles, have been plotted and the breeding areas accurately determined. 4. The bionomics of the Glossina spp., in Zululand and the dominant role of G. pallidipes in the causation of epizootics of Nagana are dealt with. 5. The cyclical appearance of Nagana epizootics at fairly regular intervals of approximately ten years and theories attempting to explain this phenomenon are considered. 6. Methods of survey for establishing the relative density of adult and immature flies are dealt with and their merits in arriving at a conception of the biotope of the different species discussed. 7. The preliminary investigations and the methods finally adopted for the application of DDT and BHC, together with the technique employed for the eradication of G. pallidipes over the entire, and G. brevipalpis in a localized area of Zululand, are described in detail. 8. The value of bush clearing as an important aid in the control of tsetse flies and the manner in which it was used in Zululand are pointed out. 9. Costs connected with the application of the procedures actually employed are compared and attention is drawn to the potentialities of the methods advocated following the experience gained. 10. The possible application of the methods used in Zululand to the eradication of at least some Glossina spp., in other parts of Africa is discussed. 11. In view of insufficient knowledge regarding methods of survey the practical eradication of G. austeni requires further investigation. Its elimination from the Union necessitates international co-operation, which would also be necessary in the case of G. brevipalpis on the international border with Portuguese East Africa. 12. The direct and indirect effects of mass applications of insecticides to extensive areas of bush upon the fauna and flora are considered.Item Subject index(Published by The Government Printer, Pretoria, 1954) Anonymous; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Item Author index(Published by The Government Printer, Pretoria, 1954) Anonymous; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.Item Studies in comparative neuropathology. I. Gliomas of the domestic fowl: their pathology with special reference to histogenesis and pathogenesis; and their relationship to other diseases(Published by The Government Printer, Pretoria, 1954) Jackson, Cecil; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.1. Fowl glioma has erroneously been classified as astrocytoma. 2. Two chief variants occur, more rarely astroblastoma and much more commonly a glioma closely related structurally to glioblastoma (spongioblastoma) multiforme of man, but in general more slowly growing. This commoner type must either be identified for purposes of classification with low-grade glioblastoma multiforme or assessed as intermediate between astroblastoma and glioblastoma. 3. "Microcystic degeneration" leading to cystic cavitation of avian gliomas is associated with the secretory ability of neoplastic glia cells. This secretion is often of demonstrably mucinous nature. The question is raised whether this phenomenon may perhaps be merely an exaggeration of the normal physiology of glia. 4. The growth of avian gliomas occurs overwhelmingly by conversion of neighbouring (adult) astrocytes to tumour cells. 5. The histopathology of a non-purulent disseminated perivascular encephalitis of fowls has been closely studied and is identical with that of the brain tissue at the spreading margin of glioma. 6. Very commonly these focal inflammatory lesions exist side by side with glioma in the same brain. 7. All possible gradations occur between these inflammatory foci and glioma. The earliest gliomas of fowls have been shown to be nothing but encephalitic foci in which glia proliferation becomes exaggerated and predominant over haematogenous cellular infiltrative changes. 8. The reacting marginal brain tissue around fowl glioma is identical in all details of its histopathology with this chronic perivascular encephalitis. Thus not only does glioma arise from encephalitis, but its continued growth and spread are similarly due to conversion of chronically inflamed brain tissue at its periphery into tumour tissue. 9. The very common occurrence of multiplicity of avian gliomas is explained as due to the progression of multiple scattered pre-existent encephalitic foci to tumours. 10. The characteristic lobulation of avian glioma is explained as due to an initial concentration of encephalitic foci which fuse as they become converted into gliomas. 11. Multiplicity of avian glioma should not be thought of as a secondary multiplicity Although gliomas may break into the ventricles, there is no evidence whatever of a spread by transplantation of tumour cells transported by the C.S.F., or by any other means. On the other hand, each of the multiple tumours is primary and bas arisen from a pre-existent focus of encephalitis. 12. The protrusion of gliomas into the ventricles is due to prior location in or near the ventricular walls of encephalitic foci which later become converted to gliomas. 13. The ependymal cells lining such stimulated ventricles readily de-differentiate into ependymal spongioblasts, but such cells have not been observed to participate in neoplasia in birds. 14. All gradations exist between the non-purulent encephalitic foci mentioned and purulent encephalitis including cerebral abscess. 15. All gradations occur between non-purulent encephalitic (and especially meningo-encephalitic) foci and lymphocytoma of the C.N.S.- or in cases where it is the plasma cell transformation of lymphocytes which becomes predominant- between encephalitis and plasmacytoma. 16. The occurrence of haemangioblastoma of the brain of the fowl is reported. The idea is entertained that these tumours also are related to glioma in the sense that they too may arise as encephalitic foci. 17. The proliferation of haematogenous infiltrating cells in gliomas as well as in disseminated meningo-encephalitis may reach neoplastic grade Thus from foci of leptomeningitis, lymphocytoma may arise and invade the brain. Neoplastic proliferation of lymphocytes in glioma lead to a variant designated glioma lymphomatosum. Neoplastic proliferation of the emigrated haematogenous monocytes gives rise to other mixed tumours designated glioma monoblastomatosum. 18. In four cases of avian glioma [three of the present author's and one of Fox (1912)] there have been concomitant liver tumours of a peculiar type. These - as might have been anticipated - are not metastatic gliomas in the liver(!) In my own cases they were cholangiocellular adenocarcinoma, cholangiocellular carcinoma, or mixed hepatocellular and cholangiocellular adenoma or adenocarcinoma; in all cases admixed with myelocytomatous neoplasia. It is suspected that these unusual findings are to be explained by the assumption that an unknown factor causing glioma (or encephalitis) may in some cases operate simultaneously on the liver, and that much more constantly in the liver than has above been mentioned in the C.N.S., this factor tends to evoke simultaneous neoplastic proliferation of emigrated haematogenous cells. 19. The relationship of a spectacular case of diffuse gliosis of the brain to glioma has been discussed. 20. Avian glioma (as well as the related lesions of non-purulent and purulent encephalitis, lymphocytomatous tumours and solid haemangioblastomas of the C.N.S., and the peculiar concomitant liver neoplasms) is characterised by the presence of an iron-containing pigment responsible for a peculiar orange to yellow coloration of all these lesions. The author believes this pigment to be of great significance, indeed that it is derived from a parasitic agent present in these lesions. 21. The theory of origin of gliomas from embryonal cells which recapitulate their ontogenetic ancestry by differentiation towards adult types is false in the case of gliomas of birds. These gliomas on the contrary arise from previously adult cells which de-differentiate into more primitive cells - a " recapitulation in reverse order" of their embryonic ancestry. 22. A suggested pathogenesis of avian glioma and related lesions has been developed in considerable detail. 23. The histopathological, histogenetic, and pathogenetic observations suggested strongly that avian glioma is a response to some noxa which continues to spread in the brain in advance of the tumour. This led to a search for the presence of a visible agent associated with glioma and related lesions of the fowl and also later in. human gliomas. Preliminary accounts of the results of this search have been published and fuller reports are in preparation.Item Studies on the comparative actions of carbamylcholine, physostigmine and neostigmine in different species of domestic animals(Published by The Government Printer, Pretoria, 1954) Clark, R.; Weiss, K.E.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.In a series of experiments the comparative actions of carbamylcholine, physostigmine and neostigmine were compared in different species. Carbamylcholine was shown to have the following undesirable effects: (i) Respiratory distress due to bronchial secretion and constriction. (ii) Marked drop in blood pressure due to vasocollapse. (iii) Production of uncoordinated contractions of the rumen and inhibition of the reticulum. (iv) Profuse salivation. . (v) Little effect on the large intestine of the horse or sheep. It was more active on the stomach and bladder than the other two drugs tested. Physostigmine and neostigmine had very similar actions characterised by: (i) A slight rise in blood pressure after therapeutic doses. Evidence is produced indicating that this may be due to adrenaline secretion. (ii) Very little effect on the heart rate, salivary secretion or bronchioles. (iii) Little effect on the stomach of the dog or donkey. Increased strength of the contractions of the rumen and reticulum. Marked stimulation of the large intestine in all species. The impression was gained that neostigmine produced purgation in equines and dogs with less signs of colic than did physostigmine.Item Isolation in mice and embryonated hen's eggs of a virus associated with vaginitis of cattle(Published by The Government Printer, Pretoria, 1954) McIntosh, B.M.; Haig, D.A.; Alexander, R.A.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.From infected material obtained from various herds virus has been isolated in several instances in developing hen's eggs, and in one instance also in mice. The strain which could be propagated in both mice and eggs was taken 25 generations by intracerebral passage in mice. In early passages day-old mice were used but later passage was continued in adult mice. In these, mortality occurred regularly after three to four days. Gradocol membrane filtration indicated that the particle diameter was Jess than 100 mµ. In developing hen's eggs this strain was propagated for twelve generations by chorio-allantoic membrane passage. Definite lesions on the membrane were observed and occasional embryos died. Subsequent passages were made by the injection of infected embryo material into the yolk sac. In this way the virus was readily maintained a further ten generations, at which stage it regularly killed all embryos. Cows and heifers infected with material from both the mouse and egg propagated lines of this strain showed definite, though mild, symptoms of vaginitis. The possibility of various forms of vaginitis occurring in bovines as well as the relation of this virus to these conditions is discussed.