1999 Onderstepoort Journal of Veterinary Research, Volume 66, 1999

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CONTENTS

*Volume 66: Number 1*

The epidemiology of rabies in Zimbabwe. 1. Rabies in dogs (Canis familiaris)	Bingham, J, Foggin, CM, Wandeler, AI & Hill, FWG	1

The epidemiology of rabies in Zimbabwe. 2. Rabies in jackals (Canis adustus and Canis mesomelas)	Bingham, J, Foggin, CM, Wandeler, AI & Hill, FWG	11

The use of chicken IgY in a double antibody sandwich ELISA for detecting African horsesickness virus	Maree, S, Du Plessis, DH, Van Wyngaardt, W, Romito, M & Du Plessis, M	25

Haemoproteus columbae in domestic pigeons in Sebele, Gaborone, Botswana	Mushi, EZ, Binta, MG, Chabo, RG, Mathaio, M & Ndebele, RT	29

Parasites of domestic and wild animals in South Africa. XXXVI. Arthropod parasites of yellow mongooses, Cynictis penicillata (G. Cuvier, 1829)	Horak, IG, Chaparro, F, Beaucournu, J-C & Louw, JP	33

Electron microscopy of Cowdria-infected macrophages suggests that in the absence of binary fission a mosaic of organisms develops from an amorphous electron dense matrix	Du Plessis, JL	39

Research communications:

A comparison of serum biochemical changes in two breeds of sheep (Red Masai and Dorper) experimentally infected with Fasciola Gigantica	Waweru, JG, Kanyari, PWN, Mwangi, DM, Ngatia, TA & Nansen, P	47

Could bats act as reservoir hosts for Rift Valley fever virus?	Oelofsen, MJ & Van der Ryst, E	51

Confirmation that PCR can be used to identify NAD-dependent and NAD-independent Haemophilus paragallinarum isolates	Miflin, JK, Chen, X, Bragg, RR, Welgemoed, JM, Greyling, JM, Horner, RF & Blackall, PJ	55

Effect of an aqueous extract of Azadirachta indica on the immune response in mice	Njiro, SM & Kofi-Tsekpo, MW	59

Book review:

Veterinary laboratories for infectious diseases - Scientific and technical review		63


*Volume 66: Number 2*

Pentastomid infections in Nile crocodiles (Crocodylus niloticus) in the Kruger National Park, South Africa, with a description of the males of Alofia simpsoni	Boomker, JDF, Junker, K & Bolton, LA	65

Ecological studies of helminth parasites of the largemouth bass, Micropterus salmoides, from Lake Naivasha and the Oloidien Bay, Kenya	Aloo, PA	73

Copper poisoning in wild ruminants in the Kruger National Park: geobotanical and environmental investigation	Grobler, DG	81

Assessment of cattle owners' perceptions and expectations, and identification of constraints on production in a peri-urban, resource-poor environment	Dreyer, K, Fourie, LJ & Kok, DJ	95

The parasitological and serological prevalence of tsetse-transmitted bovine trypanosomosis in the Eastern Caprivi (Caprivi district, Namibia)	Van den Bossche, P, Mudenge, D, Mubanga, J & Norval, A	103

Cowdria ruminantium DNA is unstable in a SuperCos1 library	Fehrsen, J, Collins, NE, Allsopp, BA, Brayton, KA, De Villiers, EP & Nxomani, C	111

Comparison of indirect fluorescent antibody test and enzyme linked immunosorbent assay in the detection of exposure of cattle to Theileria parva in Kenya	Muraguri, GR, Gitau, PK, Mwangi, MN, Mbogo, SK & Kariuki, DP	119

Control of equine piroplasmosis in Brazil	Kerber, CE, Ferreira, F & Pereira, MC	123

Characterization and observation of animals responsible for rabies post-exposure treatment in Phnom Penh, Cambodia	Reynes, JM, Soares, JL, Keo, C, Ong, S, Heng, NY & Vanhoye, B	129

Research communications:

Seroprevalence of infectious bursal disease in non-vaccinated indigenous and exotic chickens on selected farms around Gaborone, Botswana	Mushi, EZ, Binta, MG, Chabo, RG & Ndebele, RT	135

Immune responses in a horse inoculated with the VP2 gene of African horsesickness virus	Romito, M, Du Plessis, DH & Viljoen, GJ	139

Gastro-intestinal parasites of cattle in the communal grazing system of Botshabelo in the Free State	Dreyer, K, Fourie, LJ & Kok, DJ	145


*Volume 66: Number 3*

Influence of lactation on the prolactin secreting cells of the hypophysis of impala (Aepyceros melampus): An immunocytochemical and computer image analysis study	Van der Merwe, P, Meltzer, DGA & Van Aswegen, G	151

Copper poisoning in the Kruger National Park: field investigation in wild ruminants	Grobler, DG & Swan, GE	157

Attempted induction of chronic copper poisoning in boma confined impala	Grobler, DG & Swan, GE	169

Parasites of domestic and wild animals in South Africa. XXXVII. Ixodid ticks on cattle on Kikuyu grass pastures and in Valley Bushveld in the Eastern Cape Province	Horak, IG	175

Investigation of the viability of M. bovis under different environmental conditions in the Kruger National Park	Michel, AL & Tanner, M	185

Experimental studies with Strongyloides papillosus in goats	Boomker, JDF, Pienaar, JG, Basson, PA, Du Plessis, JL, Collins, HM, Naude, TW, Boyazoglu, PA, Reyers, F & Pienaar, WL	191

Neurotoxicity in calves induced by the plant, Nierembergia hippomanica Miers var. violacea Millan in South Africa	Botha, CJ, Schultz, RA, Van der Lugt, JJ, Retief, E & Labuschagne, L	237

The occurrence of Theileria and Cowdria parasites in African buffalo (Syncerus caffer) and their associated Amblyomma hebraeum ticks	Theron, J, Allsopp, BA, Allsopp, MTEP, Coetzee, ML & Dunsterville, MT	245

Research communication:

Presence of antibodies to canine distemper virus, canine parvovirus and canine adenovirus type 1 in free-ranging jackals (Canis adustus and Canis mesomelas) in Zimbabwe	Spencer, JA, Bingham, J, Heath, R & Richards, B	251


*Volume 66: Number 4*

A serological survey of bovine babesiosis in northern and eastern Zimbabwe	Katsande, TC, More, SJ, Bock, RE, Mabikacheche, L, Molloy, JB & Ncube, C	255

The production and evaluation of Pasteurella haemolytica leukotoxin in the supernatant of submerged cultures in fermenters	Odendaal, MW & Ellis, CE	265

Anthelmintic resistance in South Africa: surveys indicate an extremely serious situation in sheep and goat farming	Van Wyk, JA, Stenson, MO, Van der Merwe, JS, Vorster, RJ & Viljoen, PG	273

A comparison of the infectivity of cryopreserved versus unfrozen infective larvae of Haemonchus contortus, Trichostrongylus colubriformis and Trichostrongylus axei. Results of the Onderstepoort Veterinary Institute and collaborators from 1977 to the present	Van Wyk, JA	285

Evaluation of coloured targets for the attraction of Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa	Kappmeier, K & Nevill, EM	291

Evaluation of conventional odour attractants for Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa	Kappmeier, K & Nevill, EM	307

An anatomical study of the respiratory air sacs in ostriches	Groenewald, HB, Soley, JT & Bezuidenhout, AJ	317

Evaluation of a proposed odour-baited target to control the tsetse flies Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa	Kappmeier, K & Nevill, EM	327

Detection of Mycoplasma gallisepticum and Mycoplasma synoviae antibodies in the sera of indigenous chickens by rapid serum agglutination test at Mmopane, Gaborone, Botswana	Mushi, EZ, Binta, MG, Chabo, RG, Mathaio, M & Ndebele, RT	333

Research communication:

The helminths of ranch calves in the North-eastern Mountain Grassland of South Africa	Louw, JP	335

Author index		339

Subject index		349

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Now showing 1 - 20 of 44

Could bats act as reservoir hosts for Rift Valley fever virus?
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Oelofsen, M.J.; Van der Ryst, E.; Verwoerd, Daniel Wynand
The inter-epizootic reservoir host of Rift Valley fever virus (RVFV) remains unknown, although the namaqua rock rat, Aethomys namaquensis, as well as bats have been implicated. Bats can be asymptomatically infected with rabies, as well as several arboviruses; the possibility that they can act as host for RVFV therefore exists. To examine this possibility, 350 different samples (brain, liver, salivary glands and brown fat) obtained from 150 bats (comprising seven species) were tested for RVFV antigen using an enzyme linked immunosorbent assay (ELISA). None of the samples tested positive, but the ELISA proved to have limited sensitivity (≥103 TCID50/ml). In order to determine whether bats could be infected with RVFV, one Miniopterus schreibersii and two Eptesicus capensis bats were inoculated by the oral or intramuscular route with 100 ml and 30 ml, respectively, of a RVFV suspension with a titre of 106 TCID50/ml. None of the bats developed any clinical signs. A low concentration of RVFV antigen was found in the liver and urine of M. schreibersii, but not in brain tissue. A third E. capensis bat was inoculated by the intramuscular route and sacrificed on day 18. A low level of antigen was detected in the brown fat. These results demonstrate that bats can be infected with RVFV, and that further studies should be done to determine the potential of different bat species to act as reservoir hosts for RVFV during inter-epizootic periods.
Comparison of indirect fluorescent antibody test and enzyme linked immunosorbent assay in the detection of exposure of cattle to Theileria parva in Kenya
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Muraguri, G.R.; Gitau, P.K.; Mwangi, Michael N.; Mbogo, S.K.; Kariuki, D.P.; Verwoerd, Daniel Wynand
Appraisal of the indirect fluorescent antibody test (IFAT) and antigen enzyme linked immunosorbent assay (ELISA) serological tests as carried out to detect cattle exposed to Theileria parva at the National Veterinary Research Centre, Muguga (NVRC), Kenya is reported. Using sera from T parva naive cattle and cattle experimentally exposed to T parva, the two tests were appraised in terms of their sensitivity and specificity.IFAT and ELISA had the same sensitivity of 90% while ELISA had a higher specificity (90 %) than IFAT (80 %). A comparison was also made of the capability of the two tests to detect exposure of dairy cattle to T parva prior to immunization against East Coast fever (ECF). The positive outcome from the IFAT was significantly higher (X2 = 30,36; P < 0,001) than that from the ELISA. The agreement between the two tests was low (Kappa= 0,21 ). The two tests indicated a higher risk of ECF in the study area than was expected. Indications are that the ELISA has been effectively adopted at NVRC.
Influence of lactation on the prolactin secreting cells of the hypophysis of impala (Aepyceros melampus): An immunocytochemical and computer image analysis study
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Van der Merwe, P.; Meltzer, David George Anton; Van Aswegen, G.; Verwoerd, Daniel Wynand
Acute stress in the course of wildlife management has been intensively investigated. Chronic stress, on the contrary, has not been researched at all, probably due to the difficulty in measuring it as a result of the overriding effect of the physiological response to the restraining of wild animals. It was therefore decided to evaluate the use of immunocytochemistry, combined with computer image analysis to try and determine the magnitude of the structural changes of various hormone-secreting cells of the hypophysis. Since it was a pilot study to determine whether the combination of immunocytochemistry with computer image analysis could be of value to distinguish between two normally diverse groups, it was decided to compare the relative activity of prolactin secreting cells of lactating and nonlactating impala ewes. After transforming the prolactin immunoreactive area data by log10 to fall inside the parameters for kurtosis and skewness, a significant difference (P < 0,05, 5-% level, 2-tail) with the parametric t-test could be shown between the mean prolactin immunoreactive area of lactating (3,0751 µm2) and non-lactating (3,0467 µm2) ewes. However, the Pearson product moment (r= 0,03) showed that this difference may not be important for all practical reasons. This may be due to either sampling errors or limitations of computer image analysis, as it was often difficult to distinguish individual prolactin immunoreactive areas. Furthermore, a significant increase in the total prolactin immunoreactive areas of lactating ewes was also established. This technique, however, could distinguish between the hypophyses of lactating and non-lactating impala ewes, and with further refinement could be a useful tool in determining chronic stress in wildlife populations.
Subject index
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Anonymous; Verwoerd, Daniel Wynand
Anthelmintic resistance in South Africa: surveys indicate an extremely serious situation in sheep and goat farming
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Stenson, M.O.; Van der Merwe, J.S.; Vorster, R.J.; Viljoen, P.G.; Verwoerd, Daniel Wynand; Van Wyk, Jan Aucamp
Surveys to determine the prevalence and degree of resistance of Haemonchus spp. of sheep and goats to the available anthelmintics in South Africa indicate that small ruminant production is entering a crisis situation . Three surveys employing the faecal egg count reduction (FECR) test to determine resistance were conducted in some of the main sheep-producing areas in the summer rainfall region of South Africa, where H. contortus is the principal worm species in sheep. After analyzing the data recorded in the surveys by six different methods, including the RESO test at two different levels of confidence, the results obtained in the least stringent one (geometric mean reduction of the worm egg counts of drenched, vs untreated group of sheep) are reported in this paper, so that if any bias was obtained it would be in the favour of the anthelmintic. In Mpumalanga and KwaZulu-Natal there was anthelmintic resistance in Haemonchus spp. on all the 52 farms surveyed. Sixteen percent of the strains of H. contortus were < 60 % susceptible to three of the four anthelmintics tested , and 8 % of the strains were < 40 % susceptible to all four of the anthelmintics. FECR tests of sheep in six localities in the Lebowa district of Northern Province indicated that even in previously disadvantaged communities where anthelmintic treatment is less intensive, anthelmintic resistance is developing, and is possibly at the level at which the situation on commercial sheep and goat farms in South Africa was 25 years ago. From the data it appears that the level of anthelmintic resistance of H. contortus in South Africa is possibly the highest that has so far been recorded in the world and that strains of it are emerging that may soon not be controllable by treatment with any of the existing anthelmintics. Farmers in the summer rainfall region , if not the whole country, must be alerted to the immediate need for testing the parasite burdens of their sheep for susceptibility to preparations in all four groups of anthelmintic compounds currently available. Alternative methods of integrated worm control , including biological, must be sought and implemented with urgency, to reduce further selection for resistance and to induce reversion of the resistance that has already developed.
Author index
(Pretoria : Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Verwoerd, Daniel Wynand
A comparison of the infectivity of cryopreserved versus unfrozen infective larvae of Haemonchus contortus, Trichostrongylus colubriformis and Trichostrongylus axei. Results of the Onderstepoort Veterinary Institute and collaborators from 1977 to the present
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Verwoerd, Daniel Wynand; Van Wyk, Jan Aucamp
The infectivity for sheep of cryopreserved infective larvae (L3) of various strains of Haemonchus contortus, Trichostrongylus colubriformis and Trichostrongylus axei is compared using previously published results of trials conducted at the Onderstepoort Veterinary Institute laboratories, and of collaborators. The means and ranges of development were similar for both frozen and unfrozen larvae of two of the three worm species reviewed. A mean of 33,4% (range, 12,7-63,0 %) of cryopreserved H. contortus L3 developed, compared to a mean of 43,7% (range 2,4-78,7 %) of unfrozen L3 of this worm species. The corresponding values for T. colubriformis were 33,0% (range 10,3-62,7%), and 33,5% (range 8,3-52,2 %), respectively. In the case of T. axei, the development of the cryopreserved L3 (tested in only three trials) was markedly lower than that of unfrozen L3 in the single trial in which the latter was evaluated. It is concluded that development of cryopreserved L3 is probably similar to that of unfrozen L3 and that, for several reasons, maintaining nematode larvae in the frozen state in liquid nitrogen is a much superior method to that of one which entails cycling worm strains continually in their final hosts.
Detection of Mycoplasma gallisepticum and Mycoplasma synoviae antibodies in the sera of indigenous chickens by rapid serum agglutination test at Mmopane, Gaborone, Botswana
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Mushi, E.Z.; Binta, M.G.; Chabo, R.G.; Mathaio, M.; Ndebele, R.T.; Verwoerd, Daniel Wynand
The mean flock size was ten chickens per rural farmer. Antibodies to Mycoplasma gallisepticum and Mycoplasma synoviae were detected in 57,88 % and 67,33 % of the chicken sera respectively.
Evaluation of coloured targets for the attraction of Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Kappmeier, Karin; Nevill, E.M.; Verwoerd, Daniel Wynand
Studies on the attractiveness of various coloured targets for Glossina brevipalpis and G. austeni in South Africa showed black and pthalogen blue (p.blue) combinations to be the most effective for both species. A 2 m wide (all targets 1 m high) black/p.blue/black (colour ratio 1 :2: 1) conformation caught nearly three times more G. brevipalpis and nearly five times more G. austeni than a 1,5 m wide black standard control target. For G. brevipalpis the black/p.blue/black (1 :2:1) target should be at least 2 m wide in order to increase catches significantly while a 1,5-2,0 m wide target is optimal for G. austeni. The p.blue section of a 2 m black/p.blue/black target should not make up less than 20 % of the total target width for either species. The most effective combination of practical target sizes and colour ratios were a 1,75 m wide black/p.blue/black (1 :1,5:1) or 2 m wide target (1,5:1 :1,5). Between 61-95% of G. brevipalpis and 34-90 % of G. austeni that were attracted, settled first on the black section of black/p.blue targets (> 1 m wide). Further studies revealed that for G. brevipalpis only the black parts of the 2 m wide target need to be treated with insecticide, while the entire 1,75 m wide target should be treated. For G. austeni the total width of either target should be treated with insecticide since this species readily settles on both blue and black.
Evaluation of conventional odour attractants for Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Kappmeier, Karin; Nevill, E.M.; Verwoerd, Daniel Wynand
The components of the synthetic ox-odour used in Zimbabwe against Glossina pallidipes and G. m. morsitans were evaluated for the attraction of G. brevipalpis and G. austeni in South Africa. The Zimbabwe mixture (Zim-mix), which consisted of acetone and a 1 :4:8 mixture of 3-n-propyl phenol , 4- methyl phenol and 1-octen-3-ol, increased the catches of G. brevipalpis by c. 2,1-4,4 times compared to when no odours were used. One of the odour components, namely 3-n-propyl phenol, did not significantly increase the size of the catches. Acetone was an essential component for G. brevipalpis, especially during the warm and wet season when it acted synergistically with high doses of 1-octen- 3-ol and 4-methyl phenol. The most attractive odour combination for G. brevipalpis was 1-octen-3-ol released at 2,3-9,1 mg/h with 4-methyl phenol at c. 15,5 mg/h and acetone at c. 350 mg/h. This combination increased the catches by another 2,3-2,8 times when compared to the Zim-mix and 10,1- 12,3 times compared to 'no odour'. None of the odour components was attractive for G. austeni. None of the components was repellent for either species.
Evaluation of a proposed odour-baited target to control the tsetse flies Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Kappmeier, Karin; Nevill, E.M.; Verwoerd, Daniel Wynand
The most effective odour attractant for G. brevipalpis Newstead, namely a combination of octenol released at c. 9,1 mg/h, 4-methyl phenol released at c. 15,5 mg/h and acetone released at c. 350 mg/h, when used together with the smallest recommended colour target (as determined in previous studies), namely a 1,75 m wide x 1 m high black/pthalogen-blue/black target, was evaluated for the control of G. brevipalpis and G. austeni Newstead. This combination increased the catches of G. brevipalpis by 3,5 fold when compared to the number of those caught on a 1,5 m wide x 1 m high black target baited with a synthetic ox-odour as was used in a trial to control this species in the Hluhluwe-Umfolozi Game Reserve in 1992. There was an indication that odour (olfaction) plays a far more important role in attracting G. brevipalpis than does colour (vision). For G. austeni visual attraction appears to play the major role as the odours used were relatively unattractive to them. The odour-baited target should, however, attract G. austeni in sufficient numbers (visually) to achieve control to the fly.
An anatomical study of the respiratory air sacs in ostriches
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Bezuidenhout, A.J. (Abraham Johannes), 1942-; Verwoerd, Daniel Wynand; Groenewald, Hermanus B.; Soley, John Thomson
An accurate description of the number, location and relative position of the air sacs and their diverticula in the ostrich is essential for a better understanding of the pathogenesis of air sacculitis in this bird. The air sacs were studied in ten ostriches of varying ages by latex or silicone casting of the respiratory tract and dissection. Results revealed that the air sacs of the ostrich conform to the general pattern in birds. Cervical , lateral and medial clavicular, cranial and caudal thoracic, and abdominal air sacs are present. The left and right medial clavicular air sacs fuse with each other ventrally to the trachea to form a single, median compartment. A unique, large gastric diverticulum which covers the caudal aspects of the proventriculus and gizzard originates from the median compartment of the clavicular air sac. The lateral clavicular air sacs and their diverticula are similar to those of other bird species, with the exception that humeral diverticula are absent. Both abdominal air sacs are relatively small, with the left sac being the larger. Perirenal and femoral diverticula, similar to those found in other bird species, are present. However, the entire femur is aerated by the femoral diverticulum which also forms a large, subcutaneous division caudally and caudo-Iaterally to the femur. The presence of this subcutaneous part has practical implications for injury and intramuscular injections. The number and location of ostia connecting the air sacs to the bronchial tree are generally similar to those reported in other bird species.
The helminths of ranch calves in the North-eastern Mountain Grassland of South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Louw, J.P.; Verwoerd, Daniel Wynand
The cumulative total helminth parasite burdens of ranch calves during their first seven months of life on the North-eastern Mountain Grassland of South Africa were determined during two consecutive years. Trichostrongylus axei was the most abundant nematode parasite followed by Cooperia spp. and Ostertagia ostertagi. Haemonchus spp. occurred in relatively low numbers and its development was significantly inhibited. The total helminth parasite burdens of the calves ranged from 681 to 7269 with a mean of 4405.
Presence of antibodies to canine distemper virus, canine parvovirus and canine adenovirus type 1 in free-ranging jackals (Canis adustus and Canis mesomelas) in Zimbabwe
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Spencer, J.A.; Bingham, J.; Heath, R.; Richards, B.; Verwoerd, Daniel Wynand
A survey of free-ranging jackals (Canis adustus and Canis mesomelas) in Zimbabwe was conducted to determine the prevalence of serum antibodies to canine distemper virus (CDV), canine parvovirus (CPV) and canine adenovirus type 1 (CAV-1). Sera from 16 Canis adustus and 22 Canis mesomelas were collected from 1990 to 1993 from various regions of Zimbabwe and assayed by means of immunofluorescent techniques. Seroprevalence in C. adustus and C. mesomelas respectively were 50% and 63,6% for CDV, 12,5% and 18,2% for CPV and 37,5 and 9,1 for CAV-1. These results demonstrate that jackals are infected with these viruses and may act as reservoirs of them, although their susceptibility to the viruses is not known.
A serological survey of bovine babesiosis in northern and eastern Zimbabwe
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Katsande, Tendai C.; More, S.J.; Bock, R.E.; Mabikacheche, L.; Molloy, J.B.; Ncube, C.; Verwoerd, Daniel Wynand
The geographical distribution of Babesia bovis and Babesia bigemina antibodies in communal herds in northern and eastern Zimbabwe was determined using the ELISA technique. The animals in different herds in the study region had different levels of natural exposure to B. bovis (mean 32 %, range 0-79%) and B. bigemina (mean 52%, range 5-92%) infections. The majority of herds (90%) were endemically unstable for B. bigemina and 62 % were unstable for B. bovis. Natural region 5 and Manicaland province had the highest seroprevalence of B. bovis infection, while natural region 5 and Masvingo province had the highest seroprevalence of B. bigemina infection.
The production and evaluation of Pasteurella haemolytica leukotoxin in the supernatant of submerged cultures in fermenters
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Odendaal, M.W.; Ellis, Charlotte Elizabeth; Verwoerd, Daniel Wynand
The optimal production of P. haemolytica leukotoxin in the culture supernatant of a fluid medium is dependent on a number of factors. The leukotoxin has to be produced by using a strain that is known for its ability to produce high quantities of leukotoxin, inoculated into the most suitable type of medium at the correct culture density containing the necessary supplements and harvested after a certain growth period. The volume in which it is produced may also have an influence. Two different procedures are described to produce the leukotoxin in 5 to 15-ℓ quantities in RPMI 1640 medium. The first method used to produce leukotoxin is one that has been repeatedly described since the presence of the leukotoxin was first established in 1978. Using this method seven batches of leukotoxin were produced in litre quantities with leukotoxin activity ranging from 23-67 u/mℓ. The seed culture inoculum is prepared in brain heart infusion broth, which is centrifuged before the organisms are inoculated into RPMI 1640 medium containing 3,5% foetal calf serum and incubated for only 1 h in a fermenter, after, which the leukotoxin is harvested. An improved alternative method was devised which yielded higher levels of leukotoxin activity by utilising the ability of the P. haemolytica organisms to grow and produce leukotoxin during the logarithmic growth phase in a fermenter. A seed culture harvested in the log phase was prepared in brain heart infusion broth by means of a series of cultures and inoculated into RPMI 1640 containing 3,5% foetal calf serum. Three hours of active growth were allowed during which the leukotoxin was measured by its biological activity and an ELISA assay, and the increase in cell mass by means of the optical density every 30 min. The average leukotoxin biological activity measured 260 u/mℓ and by means of the ELISA test the leukotoxin concentration measured 315 u/ℓ which is a substantial increase in leukotoxin production. In comparison the average optical density only measured 0,469 at 650 nm. Previous findings were substantiated that the highest cell density was not reflected in the highest leukotoxin activity. It is possible to induce high levels of leukotoxin secretion in submerged cultures with RPMI1640 medium containing foetal calf serum in the controlled environment of a fermenter in large enough quantities for use as a vaccine by the improved preparation of the seed culture inoculum.
Copper poisoning in the Kruger National Park: field investigation in wild ruminants
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Grobler, D.G.; Swan, Gerry E.; Verwoerd, Daniel Wynand
Chronic copper poisoning was investigated in ruminants within the Phalaborwa area of the Kruger National Park (KNP). Exposure of ruminants to environmental copper pollution resulting from copper smelting operations of a mine in the area was examined by comparing impala faecal copper concentrations in dung heaps and tissue (liver, lung and kidney) copper concentrations of organs collected from impala and buffalo culled within three risk zones (high, moderate and low) of the study area in relation to the distance from the smelter over a period of 4 years. An additional area within the KNP not exposed to the environmental copper pollution from the mine served as control. Tissue copper accumulation was also determined in tracer impala placed in the highest risk zone. The results of this study confirmed the occurrence of chronic copper poisoning in impala and indicated an inverse relationship in extent of impala faecal copper elimination and in tissue copper accumulation in impala and buffalo with distance from the copper smelter. Impala liver copper concentrations were shown to be a reliable indicator of copper accumulation for these ruminants. The presence lung copper concentrations, indicating the exposure to airborne copper were the highest in impala culled in the zone closest to the smelter. Liver copper concentrations above the diagnostic limit of 150 ppm for chronic copper poisoning in domestic sheep were consistently found in impala within the highest risk zone. Clinical pathological measurements suggested that AST activity could possibly be used as an indicator for chronic copper poisoning in impala. It is concluded that, in addition to the environmental and geo-botanical evidence previously reported, the copper smelter of a nearby copper mine is the most likely source of copper pollution responsible for chronic copper poisoning in impala and the occurrence of high copper concentrations in buffalo in the Phalaborwa area of the KNP.
Attempted induction of chronic copper poisoning in boma confined impala
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Grobler, D.G.; Swan, Gerry E.; Verwoerd, Daniel Wynand
Induction of chronic copper poisoning in ten boma-confined impala was attempted in a randomized, single dose, parallel designed, titration study using five increasing oral doses, ranging between 125 mg/kg to 1000 mg/kg, of copper oxide needles. Two untreated impala were kept as controls. Impala (n = 1) from each treatment group were culled 52 d and 105 d after treatment and examined for tissue copper accumulation and signs of chronic copper poisoning. Despite the high doses of copper administered to the impala and liver copper concentrations above 150 ppm WM achieved in two animals, no clinical signs related to chronic copper poisoning were observed. Faecal copper concentrations indicated that the major portion of copper oxide particles was excreted in the faeces.
Parasites of domestic and wild animals in South Africa. XXXVII. Ixodid ticks on cattle on Kikuyu grass pastures and in Valley Bushveld in the Eastern Cape Province
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Verwoerd, Daniel Wynand; Horak, Ivan Gerard
Individual calves, exposed to infestation for 14 d on dry-land Kikuyu grass pastures on the coast near Alexandria, were slaughtered at approximately monthly intervals over a period of 2 years and examined for ticks. Although seven species were recovered total tick burdens were for the most part low. Changing the acaricide with which other cattle on the farm, but not the survey calves, were treated from an organophosphate-based compound to a synthetic pyrethroid resulted in a marked sustained reduction in the number of ticks on the calves. Successive pairs of yearling cattle exposed to infestation on a farm in Valley Bushveld were slaughtered at monthly intervals over a period of 2 years and examined for ixodid ticks. Eleven species were recovered, of which Amblyomma hebraeum, Haemaphysalis silacea, Rhipicephalus appendiculatus and Rhipicephalus glabroscutatum were the most abundant and prevalent. Adult A. hebraeum were generally most numerous from early to late summer, adult R. appendiculatus from mid to late summer, and adult R. glabroscutatum from spring to mid-summer.
Investigation of the viability of M. bovis under different environmental conditions in the Kruger National Park
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1999) Tanner, M.; Verwoerd, Daniel Wynand; Michel, Anita Luise
The survival time of Mycobacterium bovis in the natural habitat of infected free ranging wildlife was investigated. Seven different experimental sites near Skukuza in the Kruger National Park, South Africa, were selected to expose macroscopically affected lung or lymph node tissue of African buffalo (Syncerus caffer) origin and spiked faecal specimens for various lengths of time over a 1-year period. Mycobacterium bovis could be isolated for a maximum period of 6 weeks from tissue specimens and 4 weeks from faeces. The longest survival of M. bovis in both specimen types was observed in winter and under moist conditions. Surprisingly, the survival time of M. bovis in buried specimens seemed greatly reduced to a maximum of 5 days

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