1987 Onderstepoort Journal of Veterinary Research, Volume 54, 1987

Permanent URI for this collectionhttp://hdl.handle.net/2263/42092

Contentes Pages: Onderstepoort Journal of Veterinary Research, Vol ??, 19??

CONTENTS

*Volume 54: Number 1*

The development of an ELISA-assay for semi-quantitative detection of dihydrogriesenin, a sesquiterpene lactone from Geigeria	Verschoor, JA, Bornman, L & Vermeulen, NMJ	1

Tick transmission of Anaplasma centrale	Potgieter, FT & Van Rensburg, L	5

Production of a macrophage chemotactic factor by cultured jaagsiekte tumour cells	Verwoerd, DW, Myer, MS & Garnett, HM	9

Control of induced infestations of adult Amblyomma hebraeum with sustained release ivermectin	Soll, MD, Carmichael, IH & Gross, SJ	17

Resistance to various antibiotics of Salmonella and Escherichia coli isolated from registrable farm feeds	Durand, AM, Barnard, ML, Swanepoel, ML & Engelbrecht, MM	21

Parasites in sheep grazing on Kikuyu (Pennisetum clandestinum) pastures in the winter rainfall region	Reinecke, RK, Kirkpatrick, R, Swart, L, Kriel, AMD & Frank, F	27

Purification of the alpha toxin of Clostridium perfringens type A by ultrafiltration and gel chromatography	Odendaal, MW	39

Further studies on the clinical pathology of sweating sickness in cattle	Van Amstel, SR, Oberem, PT, Matthee, O & Reyers, F	45

Some wild hosts of the Karoo paralysis tick, Ixodes rubicundus Neumann, 1904 (Acari : Ixodidae)	Horak, IG, Moolman, LC & Fourie, LJ	49

Ovine hepatogenous photosensitivity caused by the plant Nidorella foetida (Thunb.) DC. (Asteraceae)	Schneider, DJ, Green, JR & Collett, MG	53

Leptospirosis as a cause of "white spot" kidneys in South African pig abattoirs	Hunter, P, Van der Vyver, FH, Henton, MM, Herr, S, De Lange, JF & Selmer-Olsen, A	59

The genome of Anaplasma : DNA base composition and DNA/DNA hybridization	Ambrosio, RE & Potgieter, FT	63

A single dilution enzyme-linked immunosorbent assay for the quantitative detection of antibodies to African horsesickness virus	Williams, R	67

Studies on the parasites of zebras. V. Nematodes of the Burchell's and Hartmann's mountain zebras from the Etosha National Park, South West Africa/Namibia	Krecek, RC, Reinecke, RK & Malan, FS	71

The resistance spectrum shown by a fenvalerate-resistant strain of blue tick (Boophilus decoloratus) to a range of ixodicides	Coetzee, BB, Stanford, GD & Davis, DAT	79

Resistance by the blue tick (Boophilus decoloratus) to the synthetic pyrethroid, fenvalerate	Coetzee, BB, Stanford, GD & Davis, DAT	83

Ultrastructural features of Cowdria ruminantium in midgut epithelial cells and salivary glands of nymphal Amblyomma hebraeum	Kocan, KM, Bezuidenhout, JD & Hart, A	87

Enzyme electrophoresis of South African Schistosoma mattheei and S. haematobium	Kruger, FJ	93

Research communication:

A rapid microtitration serum agglutination test for the detection of contagious equine metritis antibodies	Gummow, B, Herr, S & Brett, OL	97


*Volume 54: Number 2*

A collapsible, semi-automatic, tent-type, emergence trap, suitable for sampling Culicoides (Diptera : Ceratopogonidae) from a wide range of habitats	Pajor, ITP	99

Immunization of sheep against the larval stage of Taenia multiceps	Verster, A & Tustin, RC	103

The relationship between the skin and some bacterial species occurring on it in the Merino	Jansen, BC & Hayes, M	107

Broiler pulmonary hypertension syndrome. I. Increased right ventricular mass in broilers experimentally infected with Aegyptianella pullorum	Huchzermeyer, FW, Cilliers, JA, Diaz Lavigne, CD & Bartkowiak, RA	113

Musca nevilli sp. nov. (Diptera : Muscidae), a dung-breeding fly from South Africa	Kleynhans, KPN	115

The isolation of Leptospira interrogans serovar pomona and related serological findings associated with a mixed farming unit in the Transvaal	Gummow, B, De Lange, JF, Turner, GV & Redman, AR	119

Demonstration of growth-inhibitory as well as growth-stimulatory factors in medium conditioned by lung lavage cells stimulated with a chemotactic factor secreted by jaagsiekte tumour cells	Verwoerd, DW, Myer, MS & Garnett, HM	123

Parasites of South African Wildlife. I. Helminths of bushbuck, Tragelaphus scriptus, and grey duiker, Sylvicapra grimmia, from the Weza State Forest, Natal	Horak, IG, Boomker, J & Keep, ME	131

Descriptions of incisors of known-age Cape mountain zebras, Equus zebra zebra, from the Mountain Zebra National Park	Penzhorn, BL	135

Two field strains of Haemonchus contortus resistant to refoxanide	Van Wyk, JA, Malan, FS, Gerber, HM & Alves, RMR	143

African swine fever. II. Functional disturbances of thrombocytes in pigs infected with virulent haemadsorbing and non-haemadsorbing virus isolates	Neser, JA & Kotze, C	147

Research communications:

Antibody response in cattle to oil emulsion rabies and ephemeral fever vaccines	Cameron, CM, Barnard, BJH, Erasmus, E & Botha, WJS	157

Some features of coagulase positive staphylococci from bovine milk. II. Comparison of conventional techniques and the API Staph system	Erasmus, JA, Brand, PAJ & Galbraith, MM	159


*Volume 54: Number 3*

Heartwater: Past, Present and Future
Proceedings of a workshop held at Berg en Dal, Kruger National Park, on 8-16 September 1986

Introduction:

Welcoming address to the workshop on heartwater: past, present and future	Van der Merwe, FJ	163

The historical background and global importance of heartwater	Provost, A & Bezuidenhout, JD	165

The Organism:

Heartwater: The morphology of Cowdria ruminantium and its staining characteristic in the vertebrate host and in vitro	Prozesky, L	173

Morphology and development of Cowdria ruminantium in Amblyomma ticks	Kocan, KM & Bezuidenhout, JD	177

Distinctive staining of colonies of Cowdria ruminantium midguts of Amblyomma hebraeum	Yunker, CE, Kocan, KM, Norval, RAI & Burridge, MJ	183

Cowdria ruminantium: stability and preservation of the organism	Logan, LL	187

Heartwater: The development and life cycle of Cowdria ruminantium in the vertebrate host, ticks and cultured endothelial cells	Prozesky, L & Du Plessis, JL	193

The development of Cowdria ruminantium in neutrophils	Logan, LL, Whyard, TC, Quintero, JC & Mebus, CA	197

The present state of Cowdria ruminantium cultivation in cell lines	Bezuidenhout, JD	205

Metabolism and genetics of chlamydias and rickettsias	Williams, JC & Vodkin, MH	211

Purification of Cowdria ruminantium by density gradient centrifugation	Neitz, AWH, Vermeulen, NMJ & Viljoen, GJ	223

Purification of Cowdria ruminantium lectin cellular affinity chromatography	Vermeulen, NMJ, Neitz, AWH & Viljoen, GJ	233

Purification of Cowdria ruminantium by immunosorbent affinity chromatography	Neitz, AWH & Vermeulen, NMJ	247

The construction of genomic libraries of Cowdria ruminantium in an expression vector, lambda gt11	Ambrosio, RE, Du Plessis, JL & Bezuidenhout, JD	255

The taxonomic status of the causative agent of heartwater	Scott, GR	257

The Host:

Heartwater. An overview of the clinical signs, susceptibility and differential diagnosis of the disease in domestic ruminants	Van de Pypekamp, HE & Prozesky, L	263

Cowdria ruminantium infection in the mouse : a review	MacKenzie, PKI & McHardy, N	267

Heartwater in hosts other than domestic ruminants	Oberem, PT & Bezuidenhout, JD	271

Heartwater. The artificial transmission of Cowdria ruminantium in domestic ruminants and mice	Prozesky, L	277

The pathology of heartwater. III. A review	Prozesky, L	281

The clinical pathology and pathophysiology of heartwater: a review	Van Amstel, SR, Reyers, F, Oberem, PT, Killeen, VM & Matthee, O	287

Diagnosis of heartwater in the live animal : experiences with goats in Guadeloupe	Camus, E & Barre, N	291

The use of electro-encephalography and brain biopsy in the clinical diagnosis of heartwater	Van Amstel, SR	295

Diagnosis of heartwater at post-mortem in ruminants and the confirmation of Cowdria ruminantium in mice	Prozesky, L	301

Theoretical aspects of the enzyme-linked immunosorbent assay technique and its use in the detection of Cowdria ruminantium antigen and antibody in reacting animals	Viljoen, GJ & Vermeulen, NMJ	305

The pathogenesis of heartwater	Du Plessis, JL, Malan, L & Kowalski, ZE	313

The application of the indirect fluorescent antibody test in research on heartwater	Du Plessis & JL, Malan, L	319

Heartwater serology : some problems with the interpretation of results	Du Plessis, JL, Camus, E, Oberem, PT & Malan, L	327

The serological relationship between Cowdria ruminantium and certain members of the genus Ehrlichia	Holland, CJ, Logan, LL, Mebus, CA & Ristic, M	331

The non-specific resistance of cattle to heartwater	Du Plessis, JL & Malan, L	333

Genetic resistance of Guadeloupe native goats to heartwater	Matheron, G, Barre, N, Camus, E & Gogue, J	337

Specific immunity in farm animals to heartwater	Stewart, CG	341

Specific immunity in mice to heartwater	Stewart, CG	343

Cross-immunity between isolates of Cowdria ruminantium	Logan, LL, Birnie, EF & Mebus, CA	345

The Vectors:

Natural transmission of heartwater	Bezuidenhout, JD	349

The tick vectors of Cowdria ruminantium (Ixodoidea, Ixodidae, genus Amblyomma) and their distribution	Walker, JB & Olwage, A	353

The ecology of the African vectors of heartwater, with particular reference to Amblyomma hebraeum and Amblyomma variegatum	Petney, TN, Horak, IG & Rechav, Y	381

Some avian and mammalian hosts of Amblyomma hebraeum and Amblyomma marmoreum (Acari: Ixodidae)	Horak, IG, MacIvor, KM de F, Petney, TN & De Vos, V	397

Danger of introducing heartwater onto the American mainland: potential role of indigenous and exotic Amblyomma ticks	Barre, N, Uilenberg, G, Morel, PC & Camus, E	405

Epidemiology of heartwater in Guadeloupe and in the Caribbean	Camus, E & Barre, N	419

Problems with the interpretation of epidemiological data in heartwater: a study on 23 farms	Malan, L & Du Plessis, JL	427

The reservoir status of goats recovered from heartwater	Barre, N & Camus, E	435

Tick pheromones	Gothe, R	439

Biochemical studies on the salivary glands and haemolymph of Amblyomma hebraeum	Neitz, AWH & Vermeulen, NMJ	443

Biochemical studies on the eggs of Amblyomma hebraeum	Vermeulen, NMJ & Neitz, AWH	451

Rearing and infection techniques for Amblyomma species to be used in heartwater transmission experiments	Heyne, H, Elliott, EGR & Bezuidenhout, JD	461

Control:

The treatment of heartwater	Van Amstel, SR & Oberem, PT	475

Identification of drugs effective against Cowdria ruminantium using a mouse screening system	McHardy, N & MacKenzie, PI	481

The production of heartwater vaccine	Oberem, PT & Bezuidenhout, JD	485

The infection and treatment method of vaccination against heartwater	Van der Merwe, L	489

The block method of vaccination against heartwater	Du Plessis, JL & Malan, L	493

The efficacy of alternative routes for the infection or vaccination of animals with Cowdria ruminantium	Bezuidenhout, JD, Oliver, JA, Gruss, B & Badenhorst, JV	497

A preliminary investigation into the efficacy of intraperitoneal vaccination of sheep and goat kids against heartwater	Hurter, LR	507

Development of a prophylactic regime using Terramycin/LA to assist in the introduction of susceptible cattle into heartwater endemic areas of Africa	Purnell, RE	509

Problems encountered in the control of heartwater in Angora goats	Gruss, B	513

Chemical control of the heartwater vectors	Schroder, J	517

The use of flumethrin 1% pour-on for the control of Amblyomma spp. in various southern African countries	Hamel, HD	521

The control of heartwater by means of tick control	Bezuidenhout, JD & Bigalke, RD	525

The effect of dipping on parasitic and free-living populations of Amblyomma hebraeum on a farm and on an adjacent nature reserve	Petney, TN & Horak, IG	529

The natural control of heartwater vectors	Spickett, AM	535

Conclusion:

Future prospects and goal setting regarding research on heartwater	Bigalke, RD	543


*Volume 54: Number 4*

The control of Parafilaria bovicola transmission in South Africa	Nevill, EM, Wilkins, CA & Zakrisson, G	547

Antibiotic sensitivity of Pasteurella haemolytica isolated by means of a fibreoptic endoscope from cases of pneumonic pastereullosis in cattle	Van Amstel, SR, Henton, M, Witcomb, MA, Fabian, B & Vervoort, P	551

A comparative study of the growth of Campylobacter fetus strains in liquid media	Van der Walt, ML	553

The persistence of colostral Anaplasma antibodies and incidence of in utero transmission of Anaplasma infections in calves under laboratory conditions	Potgieter, FT & Van Rensburg, L	557

An investigation into the clinical pathological changes and serological response in horses experimentally infected with Babesia equi and Babesia caballi	De Waal, DT, Van Heerden, J & Potgieter, FT	561

The incidence of Coxiella burnetii antibodies in cattle in the Transvaal	Gummow, B, Poerstamper, N & Herr, S	569

Parasites of domestic and wild animals in South Africa. XXII. Ixodid ticks on domestic dogs and on wild carnivores	Horak, IG, Guillarmod, AJ, Moolman, LC & De Vos, V	573

Frequency and occurrence of Lactobacillus acidophilus in the gut of the pig, as indicated by its presence in the faeces	Von Aulock, MHM & Holzapfel, WH	581

Afrotropical Culicoides: a redescription of C. (Avaritia) kanagai Khamala & Kettle, 1971, reared from elephant dung in the Kruger National Park, South Africa	Meiswinkel, R	585

Seasonal abundance of carrion-frequenting blow-flies (Diptera: Calliphoridae) in the Kruger National Park	Braack, LEO & De Vos, V	591

Broiler pulmonary hypertension syndrome. II. The direct measurement of right ventricular and pulmonary artery pressures in the closed chest domestic fowl	Guthrie, AJ, Cilliers, JA, Huchzermeyer, FW & Killeen, VM	599

The occurrence of Schistosoma mattheei in the south-western Transvaal	Joubert, PH, Hamilton-Attwell, VL & Kruger, FJ	603

The colonization and life-cycles of Musca lusoria, Musca xanthomelas and Musca nevilli, vectors of Parafilaria bovicola in South Africa	Nevill, EM & Sutherland, B	607

The demonstration of the K-antigen of Campylobacter fetus venerealis using a microtitre agglutination test	Van der Walt, ML	613

The use of electronarcosis as anaesthetic in the cichlid, Oreochromis mossambicus (Peters). I. General experimental procedures and the role of fish length on the narcotizing effects of electric currents	Barham, WT, Schoonbee, HJ & Visser, JGJ	617

DNA probes for the detection of Anaplasma centrale and Anaplasma marginale	Visser, ES & Ambrosio, RE	623

The identification of factors capable of reversing the core-mediated inhibition of the bluetongue virus transcriptase	Van Dijk, AA & Huismans, H	629

Pathological findings in a natural outbreak of aflatoxicosis in dogs	Bastianello, SS, Nesbit, JW, Williams, MC & Lange, AL	635

Cardiac glycoside poisoning in sheep caused by Urginea physodes (Jacq.) Bak. and the isolated physodine A	Nel, PW, Schultz, RA, Jordaan, P, Anderson, LAP, Kellerman, TS & Reid, C	641

Experimental evidence that the active principle of the poisonous plant Thesium lineatum L.f. (Santalaceae) is a bufadienolide	Anderson, LAP, Joubert, JPJ, Schultz, RA, Kellerman, TS & Pienaar, BJ	645

Research communications:

The use of meso-erythritol sensitivity discs in the typing of Brucella strains	Pieterson, PM, Te Brugge, LA, Pienaar, BJ	651

The isolation of a paramyxovirus from pigeons in South Africa	Pienaar, ACE & Cilliers, JA	653

The transstadial transmission of Babesia caballi by Rhipicephalus evertsi evertsi	De Waal, DT & Potgieter, FT	655

Author index		657

Subject index		667

Browse

Now showing 1 - 20 of 118

Heartwater. An overview of the clinical signs, susceptibility and differential diagnoses of the disease in domestic ruminants
(Pretoria : Government Printer, 1987) Van de Pypekamp, H.E.; Prozesky, L.; Bigalke, R.D.
Heartwater is a frequently fatal tick-borne disease of ruminants caused by Cowdria ruminantium. In domestic ruminants the incubation period varies considerably and depends on the route of infection, virulence of the isolate and amount of infective material administered. Adult cattle of all breeds appear to be equally susceptible to heartwater. It is generally accepted that calves up to the age of 3 weeks have a high degree of natural resistance which is not related to the immune status of the dam. Nervous symptoms are frequently seen in animals affected by the peracute and acute forms of heartwater and can easily be confused with similar signs caused by infectious conditions, toxic plants, acaricide and heavy metal poisonings.
The taxonomic status of the causative agent of heartwater
(Published by the Government Printer, Pretoria., 1987) Scott, G.R.; Bigalke, R.D.
A fresh pragmatic classification of the rickettsias has been derived by applying the simplest techniques of numerical taxonomy. One order, the Rickettsiales, containing 3 families, the Rickettsiaceae, Phagosomaphilaceae, and the Bartonellaceae (?) is proposed. Cowdria is classified as a genus along with Chlamydia, Coxiella and Anaplasma in the tribe Chlamydieae in the family Phagosomaphilaceae.
The construction of genomic libraries of Cowdria ruminantium in an expression vector, lambda gt11
(Published by the Government Printer, Pretoria., 1987) Ambrosio, R.E.; Du Plessis, J.L.; Bezuidenhout, J.D.; Bigalke, R.D.
Genomic libraries of the Welgevonden and Kwanyanga isolates of Cowdria ruminantium have been constructed in an expression vector. These libraries contain approximately 4 x 10⁵ and 3 x 10⁵ recombinants respectively.
Purification of Cowdria ruminantium by immunoadsorbent affinity chromatography
(Published by the Government Printer, Pretoria., 1987) Neitz, Albert Walter Herman; Vermeulen, N.M.J.; Bigalke, R.D.
Immunoselective methods with special reference to immunoadsorbent affinity chromatography as a means for the isolation of Cowdria ruminantium are reviewed. Attention is given to the source of the organism, immunization, purification of antibodies, coupling of antibodies to insoluble matrixes and desorption procedures.
Purification of Cowdria ruminantium by lectin cellular affinity chromatography
(Published by the Government Printer, Pretoria., 1987) Vermeulen, N.M.J.; Neitz, Albert Walter Herman; Viljoen, G.J.; Bigalke, R.D.
This review covers the isolation of Cowdria ruminantium by lectin cellular affinity chromatography from different Amblyomma hebraeum sources. Cellular affinity chromatography has been reviewed with special attention being given to the application of this technique in the isolation of rickettsiae.
Purification of Cowdria ruminantium by density gradient centrifugation
(Published by the Government Printer, Pretoria., 1987) Neitz, Albert Walter Herman; Vermeulen, N.M.J.; Viljoen, G.J.; Bigalke, R.D.
The isolation of Cowdria ruminantium by differential and isopycnic density gradient centrifugation is reviewed with special reference to the suitability of Percoll as density gradient medium. Infected sheep brain, Amblyomma hebraeum nymphae and various mouse organs were used as starting material. By these methods, partially purified viable populations of the organism with distinctly different densities were obtained. The conclusions are based upon results of analyses of density fractions by inoculation into sheep or mice, protein determination, electron microscopy and enzyme-linked immunosorbent assay. Morphological differences were observed in the density fractions obtained from infected brain tissue and A. hebraeum.
Metabolism and genetics of chlamydias and rickettsias
(Published by the Government Printer, Pretoria., 1987) Williams, J.C.; Vodkin, M.H.; Bigalke, R.D.
Chlamydial and rickettsial diseases pose a hazard to man and to domesticated and wild animals. The virulence mechanisms which aid the establishment of these obligate intracellular parasites in the eukaryotic host are still not within our grasp. Recent knowledge of the biochemical stratagem, the metabolic capabilities and the genetic diversity of these microbes illustrate fundamental differences in ecology and evolutionary divergence. The preferred site of intracellular residence determines the strategy for uptake, for nutrient assimilation and also for evasion of the host's immunological defences. The Chlamydia, Rickettsia, and Coxiella are the most extensively studied of the genera. Whereas the Ehrlichia and Cowdria are poorly understood, they are also the most intriguing of the Rickettsiae. A number of antigenically and genetically distinct species are identified for the genera Chlamydia, Rickettsia, and Ehrlichia, whereas the Coxiella and Cowdria may not represent such a wide diversity. Recent information on the genetic heterogeneity of the chromosomal and plasmid DNAs of the strains of Coxiella suggest the diversity is greater than was originally envisioned. New information regarding the antigenic structure of Cowdria and their cellular tropisms suggests that they are closely related to the Ehrlichia. In this review we compare the metabolic capabilities and the genetic diversity of these different intracellular bacteria.
The present state of Cowdria ruminantium cultivation in cell lines
(Published by the Government Printer, Pretoria., 1987) Bezuidenhout, J.D.; Bigalke, R.D.
Attempts were made to grow 4 isolates of Cowdria ruminantium in cell lines. Three of these isolates, viz. Ball 3, Welgevonden and Kwanyanga, could be cultivated in a calf endothelial cell line, but experiments with the Kumm isolate have so far failed. The successful in vitro cultivation of 2 isolates (Welgevonden and Kwanyanga), which are also pathogenic for mice, has great potential for future studies and these aspects are discussed in this review.
The development of Cowdria ruminantium in neutrophils
(Published by the Government Printer, Pretoria., 1987) Logan, L.L.; Whyard, T.C.; Quintero, J.C.; Mebus, C.A.; Bigalke, R.D.
The sequential development of C. ruminantium (Kwanyanga and Kumm isolates) was followed in caprine leukocyte cultures by light microscopy, direct immunofluorescent microscopy (DFA), indirect immunofluorescent microscopy (IFA) and transmission electron microscopy (TEM). During the febrile response, one to several small cocci, large ring forms or rods were observed in neutrophils in blood smears and cytopreparations of neutrophil fractions using Diff Quik stain, Giemsa stain, DFA and TEM. One to several C. ruminantium colonies were seen in up to 35% of neutrophils maintained in vitro for 18 h to 5 days. The organisms were located in neutrophil phagosomes by TEM and were enveloped by two trilamellar unit membranes. Initially, C. ruminantium was tightly enclosed within phagosomes. At 20 h of incubation, organisms were frequently observed undergoing binary fission within enlarged phagosomal vacuoles. At later time periods, neutrophils harboured fully formed colonies (morula) containing numerous organisms. An occasional C. ruminantium-infected macrophage (Kumm isolate), and an occasional infected eosinophil (Kumm and Kwanyanga isolate) were found.
Heartwater: the development and life cycle of Cowdria ruminantium in the vertebrate host, ticks and cultured endothelial cells
(Published by the Government Printer, Pretoria., 1987) Prozesky, L.; Du Plessis, J.L.; Bigalke, R.D.
Various aspects of the development and life cycle of Cowdria ruminantium are discussed. C. ruminantium is transmitted transstadially by certain Amblyomma species. Apparently organisms initially develop in the gut epithelial cells of ticks and subsequent stages of C. ruminantium invade and develop in the salivary gland acini cells of the vector. Stages at which transmission to the final host are attained appear to be coordinated with the feeding cycle of the ticks and the vertebrate host is infected via salivary glands of the tick. In the vertebrate host, ticks and cultured endothelial cells, different morphological forms of C. ruminantium (electron-dense and reticulated forms) are found. Organisms enter cells through a process resembling phagocytosis and reticulated forms of the organisms appear to be the main vegetative stage. In the vertebrate host, organisms proliferate in vascular endothelial cells, neutrophils, macrophages and reticulo-endothelial cells.
Cowdria ruminantium: stability and preservation of the organism
(Published by the Government Printer, Pretoria., 1987) Logan, L.L.; Bigalke, R.D.
Blood collected in either sodium heparin or disodium edetate vacutainers from febrile goats infected with 4 isolates of Cowdria ruminantium and cryopreserved with 10% dimethyl sulphoxide at -70⁰C and -196⁰C was an effective stabilate to initiate heartwater infections in goats. A homogenized pool of whole Amblyomma variegatum ticks in Snyder's buffer, maintained at -196⁰C, was used to infect a goat with C. ruminantium. Liver and spleen collected from Swiss mice infected with the Kwanyanga isolate of C. ruminantium were homogenized in Snyder's buffer, maintained at -196⁰C and were used to initiate infections in mice. Fresh blood collected from febrile goats and maintained at 4⁰C for as long as 72 h was infectious to mice. Neutrophils separated from blood of C. ruminantium infected goats and maintained in modified RPMI medium at 37⁰C for 68 h were infectious for a goat. Similarly neutrophils from a 2nd infected goat maintained for 96 h at 37⁰C were infectious for mice.
Distinctive staining of colonies of Cowdria ruminantium in midguts of Amblyomma hebraeum
(Published by the Government Printer, Pretoria., 1987) Yunker, C.E.; Kocan, K.M.; Norval, R.A.I.; Burridge, M.J.; Bigalke, R.D.
Mallory's phloxine-methylene blue stain was used to differentiate colonies of Cowdria ruminantium in midgut epithelial cells of nymphal Amblyomma hebraeum that had been infected as larvae. Gut tissues were collected from nymphs that had fed on a susceptible sheep and were fixed in formol-saline on the day of repletion. Paraffin sections, 3-4 μm thick, were then stained and this rendered colonies and cell nuclei densely blue against a uniformly pink background of tick tissues. Colonies were easily distinguished from nuclei by their specific morphology. This method of parasite visualization may be adapted to field-collected ticks for rapid detection of C. ruminantium or to assays of susceptibility of tick populations to various strains of the organism.
Morphology and development of Cowdria ruminantium in Amblyomma ticks
(Published by the Government Printer, Pretoria., 1987) Kocan, K.M.; Bezuidenhout, J.D.; Bigalke, R.D.
The morphology and development of Cowdria ruminantium have been studied in Amblyomma hebraeum and A. variegatum. Colonies of C. ruminantium have so far been demonstrated microscopically in gut, salivary gland cells, haemocytes and malphighian tubules of infected Amblyomma ticks. Colonies in gut cells were seen in both unfed and feeding ticks but colonies in salivary gland acini were observed only in nymphs that had fed for 4 days. Although the predominant type seen in both tick stages was the reticulated form that appeared to divide by binary fission, electron dense forms were also present. The latter are similar to those forms documented in endothelial cells of the vertebrate host as well as in cell culture. The presence of colonies of C. ruminantium in salivary glands of feeding ticks, along with the demonstration of different morphologic forms of the organism, suggests that a developmental cycle of the organism occurs in its invertebrate host. It is thought that organisms first infect and develop within gut cells. From there subsequent stages continue their development in haemolymph and salivary glands and are then transferred to the vertebrate host during tick feeding. Further studies are needed to completely understand the development of C. ruminantium in ticks and its subsequent transmission by these parasites.
Heartwater: the morphology of Cowdria ruminantium and its staining characteristic in the vertebrate host and in vitro
(Published by the Government Printer, Pretoria., 1987) Prozesky, L.; Bigalke, R.D.
The morphology of Cowdria ruminantium is described and its staining characteristics in the vertebrate host and in vitro are summarized. Morphologically, the organisms are characterized in the cytoplasm of endothelial cells, macrophages and reticulo-endothelial cells. Based on the morphology of the internal structure of the organisms, elementary (electron-dense), intermediate and reticulate bodies are identified. Each organism is surrounded by a double membrane and a "capsule" is evident around a few organisms in vitro. Usually, only organisms of the same form are found within a particular vacuole, although mixed colonies are described in the in vitro studies.
The historical background and global importance of heartwater
(Published by the Government Printer, Pretoria., 1987) Bezuidenhout, J.D.; Provost, A.; Bigalke, R.D.
The first written record of what probably could have been heartwater originates from South Africa and dates back to 1838. Since then, the disease was described from almost all the African countries south of the Sahara as well as from Madagascar, Sao Tome, Reunion, Mauritius and a number of islands in the Caribbean. Most research on the disease, at least until recently, was conducted in South Africa. Progress in research was slow but a few outstanding findings are mentioned in this paper. Despite inadequate information on its actual economic impact on livestock production, it is generally accepted that heartwater is either the most or second most important tick-borne disease in Africa. Depending on the area, heartwater ranks either second or third amongst diseases such as East Coast fever, tsetse-transmitted trypanosomiasis, rinderpest and perhaps also schistosomiasis. Heartwater is a major obstacle with regard to the introduction of highly producing animals intended for the upgrading of local breeds. Furthermore, it remains a major threat to areas such as the American mainland, where potential vectors are present but where the disease does not occur.
Welcoming address to the workshop on heartwater: past, present and future
(Published by the Government Printer, Pretoria., 1987) Van der Merwe, F.J.; Bigalke, R.D.
The efficacy of alternative routes for the infection or vaccination of animals with Cowdria ruminantium
(Published by the Government Printer, Pretoria., 1987) Heartwater : Past, Present and Future. Workshop (1986 : Kruger National Park, South Africa); Bezuidenhout, J. Dürr; Olivier, J.A.; Gruss, B.; Badenhorst, J.V.; Bigalke, R.D.
The efficacy of subcutaneous, intramuscular and intraperitoneal inoculation of heartwater infective blood or nymph suspensions was tested in 5 experiments involving a total of 199 sheep. The success rate of subcutaneous injections varied greatly (0-100 %) in the different groups. However, it was found that certain additives to the inoculum, such as dimethyl sulphoxide or uninfective brain tissue, increased the efficacy of the subcutaneous route. Indications are that the site of inoculation and especially the dose volume are important factors in the success rate of such inoculations. Intramuscular injection with infective nymph suspensions containing bradikynin or hyaluronidase produced heartwater reactions in 11 out of 14 sheep. In 2 experiments, involving 25 cattle, it was found that, although very few animals showed definite reactions after the subcutaneous or intramuscular injection of nymph suspension and additives, the majority were afterwards immune to challenge. This phenomenon, which was also present in some sheep, needs further investigation.
The natural control of heartwater vectors
(Published by the Government Printer, Pretoria., 1987) Heartwater : Past, Present and Future. Workshop (1986 : Kruger National Park, South Africa); Spickett, Arthur M.; Bigalke, R.D.
Socio-economic factors and environmental considerations have increasingly encouraged the search for methods of tick control other than acaricidal treatment. Biological control management regimes have, so far, not proved to be sound replacements for acaricides. The major natural control methods employed successfully at present are host resistance and pasture management. The former has been extensively studied and utilized in a one-host-tick situation, and its potential specificity for the Amblyomma species is discussed. Pasture management in the form of tick-resistant plants and habitat modification affecting vector ecology and viability is discussed, as is host availability. Parasites and predators affecting tick populations are gleaned over with the accent on predacious birds (Buphagus species) which may play a limited role in integrated control programmes. Reference is made to the possibilities of genetic manipulation, problems accompanying the implementation of sterile male techniques, and hybrid sterility. In conclusion, a plea is made to ensure a thorough understanding of target vector ecology before any control measures are employed. This should be preferably from an integrated point of view rather than from a standpoint of unilateral reliance.
Future prospects and goal setting regarding research on heartwater
(Published by the Government Printer, Pretoria., 1987) Heartwater : Past, Present and Future. Workshop (1986 : Kruger National Park, South Africa); Bigalke, R.D.; Bigalke, R.D.
This article highlights the most important research goals identified during the workshop on "Heartwater: Past, Present and Future," which was held from 8-11 September 1986 in the Republic of South Africa. An attempt has also been made to identify the most modem technology which is available for this purpose. All 60 papers presented at the workshop, together with other relevant information, are published in this number of the Onderstepoort Journal of Veterinary Research. With regard to the causative organism it is crucial that research should be conducted on pure isolates. Moreover, existing culture methods should be improved in order to obtain better yields of organisms. Research on the hosts and vectors of Cowdria ruminantium should aim to elucidate the ways in which vector ticks become infected in nature. For this purpose especially, it will be necessary to develop rapid tests (e.g. DNA probes) to detect the organism in living animals and ticks. The nature of immunity and young animal resistance are still obscure and call for basic research. Mice and murino-tropic isolates of C. ruminantium should prove useful in this regard. Since cross-reactions with Ehrlichia occur, it is essential to give particular attention to the sero-epidemiology of Ehrlichia in conjunction with similar studies on Cowdria. The development of a tissue culture vaccine offers the greatest chance of immediate success and should be actively pursued. Studies on a recombinant vaccine should, however, be initiated because of the potential long term advantages.
The effect of dipping on parasitic and free-living populations of Amblyomma hebraeum on a farm and on an adjacent nature reserve
(Pretoria : Government Printer, 1987) Heartwater : Past, Present and Future. Workshop (1986 : Kruger National Park, South Africa); Petney, T.N.; Bigalke, R.D.; Horak, Ivan Gerard
Domestic stock on a farm 30 km north of Grahamstown were treated with an acaricide at regular intervals over a period of several years. This resulted in a marked reduction in all stages of development of Amblyomma hebraeum on kudu (Tragelaphus strepsiceros), scrub hares (Lepus saxatilis) and helmeted guinea fowl (Numida meleagris) which were on the farm compared with the burdens of similar animals in an adjacent nature reserve. The populations of free-living larvae of A. hebraeum on this farm and on another farm 10 km south of Grahamstown, on which the domestic stock were also regularly treated with acaricides, were markedly reduced when a comparison was made with the free-living populations in the adjoining nature reserves.

Browse

Recent Submissions