1996 Onderstepoort Journal of Veterinary Research, Volume 63, 1996

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CONTENTS

*Volume 63: Number 1*

Field observations on the duration of immunity in cattle after vaccination against Anaplasma and Babesia species	Tjornehoj, K, Lawrence, JA, Whiteland, AP & Kafuwa, PT	1

Effect of cyclophosphamide on the acquisition of resistance to infestation by Rhipicephalus appendiculatus in rabbits	Binta, MG, Mushi, EZ & Rurangirwa, FR	7

Biochemical and haematological values in abattoir pigs with and without subclinical lesions	Makinde, MO, Majok, AA & Hill, FWG	11

An outbreak of bovine tuberculosis in a free-living African buffalo (Syncerus caffer-Sparrman) population in the Kruger National Park: a preliminary report	Kriek, NPJ, Keet, DF, Raath, JP, De Vos, V, Huchzermeyer, HFAK & Bengis, RG	15

Adult ixodid ticks on two cattle breeds in the south-western Free State, and their seasonal dynamics	Fourie, LJ, Kok, DJ & Heyne, H	19

Geographical distribution and relative abundance of stock-associated Culicoides species (Diptera: Ceratopogonidae) in southern Africa, in relation to their potential as viral vectors	Venter, GJ, Nevill, EM & Van der Linde, TC De K	25

Redescriptions of Dichelyne (Dichelyne) rasheedae Petter, 1974 and Spirocamallanus olseni Campana-Rouget & Razarihelissoa, 1965, recorded for the first time from fish in Lake St. Lucia, South Africa	Saayman, JE & Gibbons, LM	39

Brucellosis surveillance and control in Zimbabwe: bacteriological and serological investigation in dairy herds	Mohan, K, Makaya, PV, Muvavarirwa, P, Matope, G, Mahembe, E & Pawandiwa, A	47

Research communications:

Improving the specificity of indirect immunofluorescence for the serological diagnosis of bovine anaplasmosis	Lawrence, JA, Whiteland, AP, Kafuwa, PT & Njuguna, LM	53

Subcellular localization of the nonstructural protein NS3 of African horsesickness virus	Huismans, H, Stoltz, MA, Van der Merwe, CF & Coetzee, J	57

Cryopreservation of sheathed third-stage larvae of Nematodirus spathiger	Titoy, GAP	63


*Volume 63: Number 2*

The distribution, diagnoses and estimated economic impact of plant poisonings and mycotoxicoses in South Africa	Kellerman, TS, Naude, TW & Fourie, N	65

The efficacy of amitraz against cattle ticks in Tanzania	Kagaruki, LK	91

First report of field outbreaks of ergot-alkaloid toxicity in South Africa	Schneider, DJ, Miles, CO, Garthwaite, I, Van Halderen, A, Wessels, JC & Lategan, HJ	97

Demarcation of potentially mineral-deficient areas in Central and Northern Namibia by means of natural classification systems	Grant, CC, Biggs, HC & Meissner, HH	109

The usefulness of faecal phosphorus and nitrogen in interpreting differences in live-mass gain and the response to P supplementation in grazing cattle in arid regions	Grant, CC, Biggs, HC, Meissner, HH & Basson, PA	121

Screening of the venoms of two Parabuthus scorpion species on isolated cardiomyocytes	Van Aarde, MN, Van Rooyen, JM & Van Aswegen, G	127

The osteology of the African elephant (Loxodonta africana): vertebral column, ribs and sternum	Bezuidenhout, AJ & Seegers, CD	131

The comparative host status of red veld rats (Aethomys chrysophilus) and bushveld gerbils (Tatera leucogaster) for epifaunal arthropods in the southern Kruger National Park, South Africa	Braack, LEO, Horak, IG, Jordaan, LC, Louw, JP & Segerman, J	149

Heartwater in sheep and goats: a review	Yunker, CE	159

Selenium toxicosis with focal symmetrical poliomyelomalacia in postweaning pigs in South Africa	Penrith, M-L & Robinson, JTR	171

Cryopreservation of sheathed third-stage larvae of Ancylostoma caninum (hookworm of dogs) and Ancylostoma tubaeforme (hookworm of cats)	Titoy, GAP & Malan, FS	181

Brucella melitensis biotype 1 outbreak in goats in northern KwaZulu-Natal	Reichel, R, Nel, JR, Emslie, R, Bishop, GC	183

Book review		187


*Volume 63: Number 3*

Transmission of the South African asinine strain of equine arteritis virus (EAV) among horses and between donkeys and horses	Paweska, JT, Aitchison, H, Chirnside, ED & Barnard, BJH	189

Pathogenicity differences between South African isolates of Ornithobacterium rhinotracheale	Gummow, B, Travers, AF & Coetzee, L	197

Solid-phase extraction and HPLC determination of levamisole hydrochloride in sheep plasma	Du Preez, JL & Lotter, AP	209

Effect of anti-thymocyte serum on acquisition of resistance to infestation by Rhipicephalus appendiculatus larvae in rabbits	Binta, MG, Mushi, EZ & Rurangirwa, FR	213

Changes in the incidences of the different serovars of Haemophilus paragallinarum in South Africa: a possible explanation for vaccination failures	Verschoor, JA, Bragg, RR & Coetzee, L	217

Host range, survival in dead hosts, cryopreservation, periodicity and morphology of Plasmodium durae Herman in experimental infections	Huchzermeyer, FW	227

Tuberculosis in buffaloes (Syncerus caffer) in the Kruger National Park: spread of the disease to other species	Penrith, M-L, Michel, AL, Keet, DF, Kriek, NPJ & Huchzermeyer, HFAK	239

Macroscopic blood supply to the hypophysis and hypothalamus of the ostrich (Struthio camelus)	Groenewald, HB, Elias, MZJ & Bezuidenhout, AJ	245

Heterophile antibodies to chicken erythrocytes in sheep infected with Trypanosoma congolense	Joshua, RA, Neils, JS & Oladosu, LA	253

Research communications:

In vitro cultivation of Babesia occultans	Van Niekerk, CJ & Zweygarth, E	259

Radiolabelled adult Haemonchus contortus obtained from eggs voided in the faeces of a sheep injected with 59Fe	Van Wyk, JA & Titoy, GAP	263


*Volume 63: Number 4*

Theiler Memorial Trust Award

Parasites of South African wildlife. XIV. Helminths of nyalas (Tragelaphus angasii) in the Mkuzi Game Reserve, KwaZulu-Natal	Boomker, JDF, Booyse, DG, Horak, IG, Watermeyer, R, De Villiers, IL & Flamand, JRB	265

Seasonal dynamics of the Karoo paralysis tick (Ixodes rubicundus): a comparative study on Merino and Dorper sheep	Fourie, LJ & Kok, DJ	273

Experimentally induced chronic copper toxicity in cattle	Gummow, B	277

Control of pest blackflies (Diptera: Simuliidae) along the Orange River, South Africa: 1990-1995	Palmer, RW, Edwardes, M & Nevill, EM	289

Spatial and temporal variations in the commencement of seasonal activity in the Karoo paralysis tick, Ixodes rubicundus	Horak, IG, Fourie, LJ & Kok, DJ	305

Immunophenotypic classification of canine malignant lymphoma on formalin-fixed paraffin wax-embedded tissue by means of CD3 and CD79a cell markers	Milner, RJ, Pearson, J, Nesbit, JW & Close, P	309

Culicoides (Diptera: Ceratopogonidae) associated with livestock in the Onderstepoort area, Gauteng, South Africa as determined by light-trap collections	Venter, GJ, Meiswinkel, R, Nevill, EM & Edwardes, M	315

Photosensitivity in South Africa. IX. Structure elucidation of a beta-glucosidase-treated saponin from Tribulus terrestris and the identification of saponin chemotypes of South African T. terrestris	Wilkins, AL, Miles, CO, De Kock, WT, Erasmus, GL, Basson, AT & Kellerman, TS	327

The intestine and endocrine pancreas of the African elephant: a histological, immunocytochemical and immunofluorescence study	Van Aswegen, G, De Vos, V, Schoeman, JH, Van Noorden, S & Kotze, SH	335

Distribution of viral antigen in tissues of new-born lambs infected with Rift Valley fever virus	Coetzer, JAW, Van der Lugt, JJ & Smit, MME	341

Book review		349

Author index		351

Subject index		359

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Now showing 1 - 20 of 49

The distribution, diagnoses and estimated economic impact of plant poisonings and mycotoxicoses in South Africa
(Pretoria : Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Kellerman, T. Stephanus; Naude, T.W.; Fourie, Niel; Verwoerd, Daniel Wynand
Maps are provided showing the national and provincial distributions of many plant poisonings and mycotoxicoses in South Africa. The various poisonings are briefly described and criteria for their diagnoses are given. The annual mortalities of cattle from plant poisonings / mycotoxicoses in South Africa were calculated as c. 37 665 head with a current cash value of c. R 57 627 450, and that of small stock as c.264 851 head with a value of c. R 46 878 627. The annual total cost of plant poisonings / mycotoxicoses to the livestock industry of South Africa is conservatively estimated at R 104 506 077. These figures do not include hidden losses such as diminished production, reproductive failure, the cost of not utilizing toxic pastures and the fall in price of infested land.
Redescriptions of Dichelyne (Dichelyne) rasheedae Petter, 1974 and Spirocamallanus olseni Campana-Rouget & Razarihelissoa, 1965, recorded for the first time from fish in Lake St. Lucia, South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Saayman, J.E.; Gibbons, L.M.; Verwoerd, Daniel Wynand
During a survey of parasites of fish in Lake St. Lucia, KwaZulu-Natal, South Africa, Dichelyne (Dichelyne) rasheedae was recovered from the intestines of Pomadasys commersonnii and Rhabdosargus sarba, and Spirocamallanus olseni from Rhabdosargus sarba. These are new host and geographical records. Both species of nematodes are redescribed and figured by use of light and scanning-electron microscopical techniques, and additional morphological data are provided.
Distribution of viral antigen in tissues of new-born lambs infected with Rift Valley fever virus
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Van der Lugt, Jaco J.; Smit, M.M.E.; Verwoerd, Daniel Wynand; Coetzer, Jacobus A.W.
The distribution of Rift Valley fever (RVF) viral antigen was studied by immunohistochemistry in the liver, spleen, prescapular lymph node, lungs and kidneys of eight experimentally infected new-born lambs and in four new-born lambs that died of RVF during the 1974-75 RVF epidemic. The eight experimentally infected lambs were euthanazed at 6, 12, 18, 24, 30, 33, 48 and 51 h post-infection (p.i.), respectively. Immunohistochemical staining utilized polyclonal hyperimmune mouse ascites fluid to RVF virus and peroxidase-diaminobenzidine as substrate. Virus antigen was most prominent in the liver and was detected as early as 18 h p.i. in the cytoplasm of hepatocytes that were sparsely scattered throughout the lobules. At 24-33 h p.i., antigen was also present in or adjacent to small foci of hepatocellular necrosis. At 48-51 h p.i. and in one of the field cases, positive staining was widespread and most consistently present in the cytoplasm of large numbers of degenerated or necrotic hepatocytes and in a few acidophilic bodies. Immunohistochemical staining was rarely observed in hepatocyte nuclei. Almost diffuse histochemical staining was observed in disintegrated cells and in the cytoplasm of necrotic hepatocytes throughout the liver in the other three field cases with pannecrosis; only the primary foci of necrosis and a narrow periportal rim of intact hepatocytes did not stain. No staining was observed in bile duct epithelium, endothelial and Kupffer cells in the initial stages of infection, supporting the contention that hepatocytes constitute the primary site of RVF virus replication in new-born lambs. Few cells stained positively in the spleen, prescapular lymph node, lungs and kidneys.
Heterophile antibodies to chicken erythrocytes in sheep infected with Trypanosoma congolense
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Joshua, R.A.; Neils, J.S.; Oladosu, L.A.; Verwoerd, Daniel Wynand
High hemagglutinin titres against chicken erythrocytes were detected in the sera of Trypanosoma congolense-infected sheep. Adsorption of sheep sera with solubilized T. congolense resulted in marked reduction of hemagglutinin titre. Heat inactivation of the sera at 56°C for 30 min. had no demonstrable effects on the hemagglutinin titre. Sera collected from the sheep before trypanosome infection did not agglutinate chicken erythrocytes. On the other hand, erythrocytes of horse, donkey and dog were agglutinated at very high titres by sera collected both pre-infection and during the course of infection. Erythrocytes from bovine and caprine species were not agglutinated by contemporaneous sera at both low and high dilutions. Hemagglutinin titres for chicken erythrocytes returned promptly to pre-infection levels in chemotherapeutically terminated infections. The brand of trypanocide used, had no effect on the course of the hemagglutinin titre's return to a normal level.
In vitro cultivation of Babesia occultans
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Verwoerd, Daniel Wynand; Van Niekerk, C.J.; Zweygarth, Erich
Babesia occultans, the causative agent of a benign form of cattle babesiosis in South Africa, was continuously cultivated in microaerophilous stationary-phase culture. A modified medium, 199, supplemented with either 40% (v/v) bovine or 40% (v/v) horse serum, was used. Cultures were initiated in a humidified atmosphere containing 2% 0₂, 5% C0₂, and 93% N₂. The highest percentage of parasitized erythrocytes (PPE) reached 4,5% in horse-serum- and 2,4% in bovine-serum-supplemented medium. Parasite suspensions were cryopreserved and successfully resuscitated.
Author index
(Pretoria : Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Verwoerd, Daniel Wynand
Book review
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Anonymous; Verwoerd, Daniel Wynand
Subject index
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Anonymous; Verwoerd, Daniel Wynand
The comparative host status of red veld rats (Aethomys chrysophilus) and bushveld gerbils (Tatera leucogaster) for epifaunal arthropods in the southern Kruger National Park, South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Jordaan, Leonora C.; Louw, J.P.; Segerman, Joyce; Verwoerd, Daniel Wynand; Braack, L.E.O.; Horak, Ivan Gerard
Red veld rats (Aethomys chrysophilus) and bushveld gerbils (Tatera leucogaster) were trapped at monthly intervals, when possible, over a 2-year period, in the southern Kruger National Park, Mpumalanga Province. Forty-six specimens of each species were caught, euthenased and microscopically examined for fleas, lice, ticks and mites. Clear differences existed between the two rodent hosts in infestation intensity and also parasite species. The flea, Xenopsylla brasiliensis, commonly and exclusively utilized red veld rats, whereas Xenopsylla frayi was common and specific to bushveld gerbils. T leucogaster were commonly infested with the lice Hoplopleura biseriata and Polyplax biseriata, while only a single A. chrysophilus hosted the louse, Hoplopleura patersoni. Red veld rats harboured small numbers of the immature stages of Haemaphysalis leachi / spinulosa and relatively large numbers of Rhipicephalus simus. The larvae of R. simus were irregularly collected from February to September and the nymphs from March to November. Bushveld gerbils hosted fewer ticks than did the rats, with a single specimen of H.leachi / spinulosa and low numbers of immature Hyalomma truncatum, the latter erratically present from June to October. Mites were abundant on both rodent hosts, A. chrysophilus hosting 13 species in six families, and T leucogaster hosting 12 species representing seven families, with clear differences in mite assemblages between the two rodents. As the rats and gerbils were collected from the same trap lines at the same times, the differences in species composition and infestation intensity of their parasites, suggest that immunological, behavioural or other segregating mechanisms are in operation to maintain discrete parasite assemblages.
The intestine and endocrine pancreas of the African elephant: a histological, immunocytochemical and immunofluorescence study
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Van Aswegen, G.; De Vos, Valerius; Schoeman, J.H.; Van Noorden, Susan; Kotze, Sanet H.; Verwoerd, Daniel Wynand
Histological, immunocytochemical and immunofluorescence methods were employed to study the intestine and endocrine pancreas of the elephant. The histological findings were in line with those in monogastric mammals. In the mucosa of intestine, endocrine cells were immunoreactive to somatostatin, gastrin, CCK, GIP, secretin, motilin, glucagon and NPY. Nerve cells immunoreactive to somatostatin, substance P, VIP, PHI, NPY, bombesin and CGRP were detected. No immunoreactivity to neurotensin was observed. Islets of the pancreas had insulin cells in their cores and glucagon and somatostatin cells in their mantles. The antisera employed failed to demonstrate PP cells in the pancreas, but NPY immunoreactive cells were present.
Changes in the incidences of the different serovars of Haemophilus paragallinarum in South Africa: a possible explanation for vaccination failures
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Bragg, Robert Richard; Coetzee, L.; Verwoerd, Daniel Wynand; Verschoor, Jan Adrianus
Infectious coryza remains an important disease in the poultry industry despite the long-term and widespread use of vaccines against its causative agent, Haemophilus paragallinarum, in South Africa. In order to detect antigenic changes between populations of H. paragallinarum isolated before the use of vaccines against infectious coryza in this country, and field isolates obtained after the introduction of infectious coryza vaccines, 106 different NAD-dependent isolates (of which 93 were identified as H. paragallinarum) from 63 different farms, and dating from 1972 to March 1995, were identified by means of rabbit antisera against serogroups A, B and C. Serogroup C isolates show weaker cross-protection, requiring the further subdivision of this serogroup into its four different serovars. The percentages of the different serovars obtained in the 1970s, confirmed previously published data on South African isolates. A tendency towards a decrease in the number of serogroup A and serovar C-2 isolates, and an increase in the percentage of serovar C-3 isolates, was noted among isolates of the 1980s. These changes were markedly enhanced in the isolates obtained from 1990 to March 1995. The percentage of serogroup A isolates decreased significantly from 34% in the 1970s to only 5% in the 1990s, and that of serovar C-2 isolates, from 31-18%, while the abundance of serovar C-3 isolates increased significantly from 31% in the 1970s to 73% in the 1990s. Serogroup B remained more or less constant and never reached more than 10% of the population. These results indicate the need for the incorporation of serovar C-3 in a vaccine for use in South Africa, particularly in those areas of the country from which isolates were collected during this study. Some of the NAD-dependent isolates obtained from poultry in South Africa between 1970 and 1995, were biochemically identified as Pasteurella avium and P. volantium. As H. avium has been subdivided and reclassified into the genus Pasteurella, this represents the first report of the identification of P. avium and P. volantium in South Africa.
Host range, survival in dead hosts, cryopreservation, periodicity and morphology of Plasmodium durae Herman in experimental infections
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Verwoerd, Daniel Wynand; Huchzermeyer, Fritz W.
In experimental infections, fowl , duck, guineafowl and canary were refractory to Plasmodium durae, which in Japanese quail produced low and transient infections, but a high and long-lasting parasitaemia in a Lady Amherst pheasant. Heart, blood and brain of dead hosts injected into turkeys, allowed the recovery and further passaging of the live parasite. This technique could be useful for the recovery of malaria parasites from suspect postmortem material. Intravenous infection produced parasitaemias in chicken and turkey embryos, while attempts at allantoic-sac infections of chicken embryos were unsuccessful. A certain degree of periodicity of schizogony was demonstrated. The South African isolates of P. durae had smaller schizonts than those described from East and West Africa, with 2-14 merozoites (mostly four) . Some strains did not produce mature gametocytes in the experimental hosts. Exoerythrocytic schizonts of P. durae are depicted in this paper for the first time.
Effect of anti-thymocyte serum on acquisition of resistance to infestation by Rhipicephalus appendiculatus larvae in rabbits
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Binta, M.G.; Mushi, E.Z.; Rurangirwa, F.R.; Verwoerd, Daniel Wynand
Administration of specific goat anti-thymocyte serum (ATS) to rabbits, prior to a primary infestation by Rhipicephalus appendiculatus larvae, blocked the acquisition of resistance significantly only in the third infestation. The larvae which fed on these rabbits had higher engorgement masses than did those feeding on untreated control rabbits. Also, a higher percentage (92%) of larval ticks fed on these animals than on the controls (88%). ATS also induced a leucopenia due to a lymphopenia in the treated rabbits. It was concluded that a T-cell-dependent component might be involved in acquired resistance to infestation by R. appendiculatus.
Tuberculosis in buffaloes (Syncerus caffer) in the Kruger National Park: spread of the disease to other species
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Keet, D.F.; Kriek, N.P.J.; Huchzermeyer, Hildegard F.A.K.; Verwoerd, Daniel Wynand; Penrith, Mary-Louise; Michel, Anita Luise
Tuberculosis, caused by Mycobacterium bovis, was recently diagnosed in a cheetah (Acinonyx jubatus) , two lions (Panthera leo) and a chacma baboon (Papio ursinus) from the Kruger National Park (KNP). It is assumed that they contracted the disease directly or indirectly from tuberculous buffaloes in the park. Tuberculous granulomatous lesions in the lungs were extensive and constituted the predominant changes in all three animal species. These pulmonary lesions included tuberculous bronchiolitis and cavitation which would facilitate dissemination of M. bovis into the environment. Spread of the disease to free-ranging species (in which it has not previously been reported) that may act as maintenance hosts of the infection, is a matter of serious concern.
Photosensitivity in South Africa. IX. Structure elucidation of a beta-glucosidase-treated saponin from Tribulus terrestris and the identification of saponin chemotypes of South African T. terrestris
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Wilkins, A.L.; Miles, Christopher O.; De Kock, W.T.; Erasmus, G.L.; Basson, A.T.; Kellerman, T. Stephanus; Verwoerd, Daniel Wynand
Saponin C, a β-glucosidase-treated saponin isolated from ethanol-water extracts of a South African collection of Tribulus terrestris, was shown by one- and two-dimensional NMR spectroscopy to be ruscogenin 1-O-α-L- rhamnopyranosyl-(1→2)-β-D-6-O-acetylglucopyranoside.GC-MS analysis of the hydrolysed ethanol-water (4:1) extracts of T. terrestris specimens from two of four sites, revealed high levels of ruscogenin and potentially lithogenic diosgenin saponins. Specimens from two other sites contained non-lithogenic saponins derived predominantly from tigogenin, neotigogenin, gitogenin and neogitogenin.
Macroscopic blood supply to the hypophysis and hypothalamus of the ostrich (Struthio camelus)
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Elias, M.Z.J. (Mario Zefanias Joao); Bezuidenhout, A.J. (Abraham Johannes), 1942-; Verwoerd, Daniel Wynand; Groenewald, Hermanus B.
The branching pattern of the Aa. carotes internae and the macroscopic blood supply to the hypophysis and hypothalamus of the ostrich were studied on ten dissected acrylic vascular-injected heads and ten corrosion preparations of acrylic vascular casts of the head. The A. carotis cerebralis was found to be the only source of blood supply to the hypophysis and hypothalamus. The neurohypophysis was supplied by the caudal hypophyseal and infundibular arteries. The pars distalis was supplied by portal vessels from the ventral hypothalamic region,and it also received arterial blood directly from the infundibular arteries. The hypothalamus received blood from the Aa. infundibulares, A. ventralis tecti mesencephali and A. preopticae.
Immunophenotypic classification of canine malignant lymphoma on formalin-fixed paraffin wax-embedded tissue by means of CD3 and CD79a cell markers
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Milner, R.J.; Pearson, J.; Nesbit, J.W.; Close, P.; Verwoerd, Daniel Wynand
Canine malignant lymphoma (CML) is a common lymphoid tumour. Identification of the immunophenotype is of prognostic importance; T-cell lymphomas have a worse prognosis than B-cell lymphomas. Until recently, identification of T- or B-cell lymphomas was undertaken by means of flow cytometry or fluorescent immunocytochemistry on frozen sections. Whilst valid in the research field, these methods are impractical for routine diagnostic histopathology in CML. Commercially available CD3 antibody has been successfully employed in T-cell identification in dogs in formalin-fixed paraffin wax-embedded tissue sections, but the lack of a B-cell marker has been a hindrance until the recent introduction of a commercially available pan-B cell marker, CD79a (DAKO M7051), suitable for diagnostic application upon formalin-fixed paraffin wax-embedded material. Antibody markers to CD3 and CD79a show cross-reactivity across species lines for B cells and T cells respectively. In this group of five selected canine cases, two were identified as B-cell and the other three as T-cell lymphoma, by means of CD3 and CD79a. To the best of our knowledge application of CD79a in cases of CML has not been reported.
Culicoides (Diptera: Ceratopogonidae) associated with livestock in the Onderstepoort area, Gauteng, South Africa as determined by light-trap collections
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Meiswinkel, R.; Nevill, E.M.; Edwardes, M.; Verwoerd, Daniel Wynand; Venter, Gert Johannes
In 54 light-trap collections made at 28 sites in the Onderstepoort area a total of 178 941 Culicoides midges of 35 species was collected in March 1988; the survey was repeated at 26 sites in September and yielded 19 518 Culicoides of 24 species. The number of Culicoides species collected totalled 38. C. imicola was the most abundant species at 27 of the 28 sites sampled, and accounted for 88% and 67% of all midges collected in the two months respectively. This study not only confirms that C. imicola is widespread and abundant in the greater Onderstepoort area, but also that its numbers correlate positively with the historical prevalence of African horse sickness (AHS) and bluetongue (BT) locally. The high numbers of C. imicola make Onderstepoort the ideal site for the study of its laboratory vector capacity. The relatively low numbers of Culicoides spp. other than C. imicola in the Onderstepoort area, will severely limit studies on their roles in the transmission of arboviruses. The origin of the blood-meals of 1 338 engorged Culicoides belonging to 13 species was determined by means of a cross-over electrophoresis precipitin test; C. imicola fed on cattle, horses, sheep and pigs. Four other Culicoides species showed a similarly wide host range.
Spatial and temporal variations in the commencement of seasonal activity in the Karoo paralysis tick, Ixodes rubicundus
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Fourie, L.J.; Kok, D.J.; Verwoerd, Daniel Wynand; Horak, Ivan Gerard
Successful prophylaxis of paralysis, induced in small stock by feeding female Ixodes rubicundus, is dependent on the accurate determination of the commencement of seasonal activity by the tick. The commencement of this activity was recorded for 11 consecutive years on a farm in the south-western Free State, South Africa, and for shorter periods on other farms, some of these in regions with markedly colder climates. The colder the mean minimum atmospheric temperatures during the 2 months preceding the start of tick activity, the earlier it commenced. This could differ by 4 weeks from year to year on the same farm. In a region with a low effective temperature activity commenced between 3-8 weeks earlier than in a region with a higher effective temperature.
Experimentally induced chronic copper toxicity in cattle
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1996) Verwoerd, Daniel Wynand; Gummow, Bruce
Eight Bonsmara bulls and eight Bonsmara heifers, having masses of between 210 and 266 kg when selected, were randomly allocated to four groups, each comprising two bulls and two heifers. Group 1 received 0,6 mg of copper (Cu)/kg of body mass per day (bm/d), group 2, 10 mg of Cu/kg of bm/d and group 3, 20 mg of Cu/kg of bm/d as a copper sulphate solution, given orally, 5 d a week over 745 d. Group 4 was the control group. One bull from group 3 was euthanased on day 679 of the trial, a heifer from group 3 and a bull from group 2, on day 695 of the trial, and a heifer from group 2, on day 731 of the trial, after they had shown clinical signs. During the course of the trial, clinical signs, serum gamma glutamyltransferase and aspartate aminotransferase activity, blood urea nitrogen, and plasma copper, zinc and iron concentrations were monitored. Live mass was recorded weekly to determine any effect on mass gain. The liver and kidney copper, zinc, iron and manganese concentrations at the time of death or slaughter are given. From the results it was concluded that subclinical damage to the liver and eventual copper toxicity can occur when cattle are continually exposed to oral doses ≥12 mg of Cu/kg of bm/d. It was also concluded that cattle can probably tolerate oral doses of ≤0 ,6 mg of Cu/kg of bm/d for an indefinite period, provided there are no other sources of copper, such as may occur with air-pollution, or provided no other adverse mineral interactions occur, such as may occur with molybdenum deficiency.

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