1994 Onderstepoort Journal of Veterinary Research, Volume 61, 1994

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CONTENTS

*Volume 61: Number 1*

Effect of heat-stress on conception in a dairy-herd model in the Natal highlands of South Africa	Du Preez, JH, Willemse, JJC & Van Ark, H	1

A method for the assessment of blackfly (Diptera: Simuliidae) attraction to and engorgement on sheep in South Africa	Kok, DJ, Fourie, LJ & Oberem, PT	7

Helminth and arthropod parasites of indigenous goats in the northern Transvaal	Boomker, JDF, Horak, IG & Ramsay, KA	13

The clinical pathology of heartwater. III. Changes in blood clotting, blood calcium, blood protein, haematocrit and white-cell counts in sheep with experimentally induced heartwater	Van Amstel, SR, Reyers, F, Myburgh, E, Pretorius, G & Sacks, P	21

Studies on the presence of endotoxin activity and inflammatory products (Leukotrienes) in cases of experimentally induced heartwater in sheep	Van Amstel, SR, Myburgh, E, Mundell, J & Davidson, B	29

Parasites of South African freshwater fish. VI. Nematode parasites of some fish species in the Kruger National Park	Boomker, JDF	35

Changes in the blood-gas status of sheep with experimentally induced heartwater	Van Amstel, SR, Reyers, F & Myburgh, E	45

Osteology of the pelvic limb of the African elephant (Loxodonta africana)	Smuts, MMS & Bezuidenhout, AJ	51

Pseudorabies and transmissible gastroenteritis: a serological survey in South Africa	Williams, R, Esterhuysen, JJ & Robinson, JTR	67

Ecology and epidemiology of anthrax in the Etosha National Park, Namibia	Lindeque, PM & Turnbull, PCB	71

Afrotropical Culicoides: description and comparison of the pupae of seven species of the Similis supergroup (Diptera: Ceratopogonidae)	Nevill, H & Dyce, AL	85

Research communication:

Putative avocado toxicity in two dogs	Buoro, IBJ, Nyamwange, SB, Chai, D & Munyua, SM	107

Guide for authors		111


*Volume 61: Number 2*

A rapid method of estimating the abundance of immature blackflies (Diptera: Simuliidae)	Palmer, RW	117

Eight new Afrotropical Spinitectus spp. (Nematoda: Cystidicolidae) from freshwater fishes with a key to the members of the genus in the Region	Boomker, JDF & Puylaert, FA	127

Sequential feeding of Ixodes rubicundus on its natural host, Elephantulus myurus: effects on tick mass and on engorgement and moulting success	Horak, IG, Du Toit, JS & Fourie, LJ	143

Detachment rhythms of immature Ixodes rubicundus from their natural host, the rock elephant shrew (Elephantulus myurus)	Horak, IG, Du Toit, JS & Fourie, LJ	149

African horsesickness epidemiology: five species of Culicoides (Diptera: Ceratopogonidae) collected live behind the ears and at the dung of the African elephant in the Kruger National Park, South Africa	Braack, LEO & Meiswinkel, R	155

A nervous disorder in cattle, caused by the plants Ficus ingens var. ingens and Ficus cordata subsp. salicifolia	Myburgh, JG, Fourie, N, Kellerman, TS, Cornelius, ST, Ward, C & Van der Lugt, JJ	171

A histocytochemical study of mucus glycoproteins or mucins in the intestinal tract of the African elephant (Loxodonta africana)	Kotze, SH & Coetzee, HL	177

Application of immunoperoxidase techniques to formalin-fixed brain tissue for the diagnosis of rabies in southern Africa	Last, RD, Jardine, JE, Smit, MME & Van der Lugt, JJ	183

Research communications:

Evaluation of a short-term in vitro growth-inhibition test to determine susceptibility of Trypanosoma vivax stocks to various trypanocides	Zweygarth, Er, Kaminsky, R & Moloo, SK	189

First isolation of Campylobacter jejuni from the vaginal discharge of three bitches after abortion in South Africa	Odendaal, MW, De Cramer, KGM, Van der Walt, ML, Botha, AD & Pieterson, PM	193

Parasites of South African freshwater fish. VII. Nematodes of some scaled fishes from the Hartbeespoort Dam, Transvaal	Boomker, JDF	197

Book review:

Risk analysis, animal health and trade		201


*Volume 61: Number 3*

Serum- and bone-mineral status of ostriches with tibiotarsal rotation	Soley, JT, Bezuidenhout, AJ, Burger, WP & Reyers, F	203

Neuropeptides in the myenteric ganglia and nerve fibres of the forestomach and abomasum of grey, white and black Karakul lambs	Groenewald, HB	207

Photosensitivity in South Africa. VII. Chemical composition of biliary crystals from a sheep with experimentally induced geeldikkop	Coetzer, JAW, Miles, CO, Wilkins, AL, Erasmus, GL & Kellerman, TS	215

The oesophagus and stomach of the African elephant: a histological, immunocytochemical and immunofluorescence study	Van Aswegen, G, Schoeman, JH, De Vos, V & Van Noorden, S	223

The identification of Mycoplasma conjunctivae as an aetiological agent of infectious keratoconjunctivitis of sheep in South Africa	Van Halderen, A, Van Rensburg, WJJ, Geyer, A & Vorster, JH	231

Ultrastructure of ostrich (Struthio camelus) spermatozoa. II. Scanning electron microscopy	Soley, JT & Roberts, DC	239

Perinatal mortality in lambs of ewes exposed to cultures of Diplodia maydis (= Stenocarpella maydis) during gestation. A study of the central-nervous-system lesions	Prozesky, L, Kellerman, TS, Maartens, BP, Schultz, RA & Swart, DP	247

Early and late transcriptional phases in the replication of lumpy-skin-disease virus	Fick, WC & Viljoen, GJ	255

Trypanosomes of some sub-Saharan birds	Squires-Parsons, D, Bennett, GF & Earle, RA	263

Research communication:

Bovine besnoitiosis: transfer of colostral antibodies with observations possibly relating to natural transmission of the infection	Shkap, V, Pipano, E, Marcus, S & Krigel, Y	273


*Volume 61: Number 4*

The Theiler Memorial Trust Award

The detection of antibodies cross-reacting with Cowdria ruminantium in the sera of domestic ruminants in regions of South Africa where Amblyomma hebraeum does not occur	Du Plessis, JL, Boersema, BR & Van Strijp, MF	277

Evidence for cryptosporidial infection as a cause of prolapse of the phallus and cloaca in ostrich chicks (Struthio camelus)	Penrith, M-L, Bezuidenhout, AJ, Burger, WP & Putterill, JF	283

Isolation and preliminary characterization of a caprine rotavirus	Da Costa Mendes, VM, De Beer, MC, Goosen, GH & Steele, AD	291

A survey of the incidence and importance of the tick-borne diseases heartwater, redwater and anaplasmosis in the heartwater-endemic regions of South Africa	Stoltsz, WH, Du Plessis, JL & De Waal, DT	295

Vanadium air pollution: a cause of malabsorption and immunosuppression in cattle	Gummow, B, Bastianello, SS, Botha, CJ, Smith, HJC, Basson, AJ & Wells, B	303

A bioequivalence and pharmacokinetic evaluation of two commercial diminazene aceturate formulations administered intramuscularly to cattle	Gummow, B, Swan, GE & Du Preez, JL	317

The virtual absence of Culicoides imicola (Diptera: Ceratopogonidae) in a light-trap survey of the colder, high-lying area of the eastern Orange Free State, South Africa, and implications for the transmission of arboviruses	Venter, GJ & Meiswinkel, R	327

A rapid method to quantify bacterial contamination on hatching eggs. I. Correlation of optical density with initial bacterial count	Pienaar, ACE, Coetzee, L & Bragg, RR	341

Photosensitivity in South Africa. VIII. Ovine metabolism of Tribulus terrestris saponins during experimentally induced geeldikkop	Miles, CO, Wilkins, AL, Erasmus, GL & Kellerman, TS	351

Articles presented at the 23rd Annual Congress of the Parasitological Society of Southern Africa as part of the David Bruce centenary celebration

Understanding tsetse flies	Langley, PA	361

Sleeping sickness and the central nervous system	Pentreath, VW, Baugh, PJ & Lavin, DR	369

The impact of nagana	Connor, RJ	379

Epidemiology and control of trypanosomosis	Chadenga, V	385

Research communications:

Epidemiology of African horsesickness: duration of viraemia in zebra (Equus burchelli)	Barnard, BJH, Bengis, RG, Keet, DF & Dekker, EH	391

Bile enhances the infectivity of third stage larvae of Dictyocaulus filaria	Titoy, GAP & Schwan, EV	395

Author index		397

Subject index		405

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Now showing 1 - 20 of 53

Putative avocado toxicity in two dogs
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Buoro, I.B.J.; Nyamwange, S.B.; Chai, D.; Munyua, S.M.; Verwoerd, Daniel Wynand
Two dogs were seen at the University Veterinary Teaching Hospital, Nairobi, Kenya, both having histories of dyspnoea, progressively enlarging abdomens, anasarca, ascites, pleural and pericardial effusion, and pulmonary oedema. One of the dogs had a mild neutrophilic leucocytosis, elevated levels of alkaline phosphatase, alanine aminotransferase, lactate dehydrogenase and proteinuria. Histopathological examination of the myocardium revealed some damage to myocytes and a mononuclear cellular infiltration involving the myocardium, liver and kidneys. The two dogs had a fondness for avocado fruits and, as the presenting syndrome is identical to that seen in goats, sheep and horses poisoned by avocados, a comparison is made and the probable manifestation of this poisoning presented.
Afrotropical Culicoides : description and comparison of the pupae of seven species of the Similis supergroup (Diptera: Ceratopogonidae)
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Nevill, Hilda; Dyce, A.L.; Verwoerd, Daniel Wynand
The pupae of Culicoides exspectator Clastrier, C. kobae Cornet & Chateau, C. micheli Cornet & Chateau, C. olyslageri Kremer & Nevill, C. ravus De Meillon and C. (Synhelea) tropicalis Kieffer are described and illustrated for the first time, and the pupa of C. similis Carter, Ingram & Macfie is redescribed. All seven species belong to the Similis supergroup; the immature stages of six are found in ground waters while those of C. olyslageri occur in tree holes. A concise key is presented for differentiating the seven species. Short notes on their larval habitats are given. Reference is made to C. accraensis Carter, Ingram & Macfie, also found in tree holes. Available data suggest that pupal morphology can be used to differentiate closely related species; group characters also exist for those species within the Similis supergroup which can be used to separate ground-water species from those utilizing tree holes. Indications are that the pupae are of limited help in resolving the systematic subdivision of the Similis supergroup.
Ecology and epidemiology of anthrax in the Etosha National Park, Namibia
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Lindeque, P.M.; Turnbull, P.C.B.; Verwoerd, Daniel Wynand
Analysis of mortality records has revealed distinct patterns in the incidence of anthrax in elephant and plains ungulates. The seasonal peak among the former is in November at the end of the dry season, while among the latter it occurs in March towards the end of the rainy season. Among elephants, there has been a notable spread of the disease to the west of the Park. Age and sex analyses indicate that, except for zebra, proportionally greater numbers of adult males die of anthrax among the species predominantly affected; however, zebra carcases are difficult to sex. In a study to identify possible environmental sources of infection, B. anthracis was detected in 3,3% of 92 water and 3,0% of 230 soil samples collected at different times of the year from 23 sites not associated with known cases of anthrax. Slight seasonal differences were noted with 5,7% positives occurring in the cold-dry period (May to August), 3,5% in the hot-dry season (September to December) and 1,4% in the hot-wet season (January to April). Higher rates (26,0% of 73 samples) were found in water from waterholes in the western part of the Park at the time of an outbreak in elephants. The possible importance of scavenger faeces was confirmed with > 50% of vulture, jackal and hyaena faeces collected from the vicinity of confirmed anthrax carcases yielding B. anthracis , sometimes in substantial numbers, while no spores were found in faeces not associated with known anthrax carcases. Despite terminal B. anthracis levels of usually > 10⁷ cfu/ml in the blood of animals dying of anthrax, spore levels in soil contaminated by such blood at sites of anthrax carcases ranged from undetectable to a few tens of thousands. The rapid loss of viability in soil and water of anthrax bacilli was monitored experimentally and the importance of soil type demonstrated. Survival and extent of sporulation of the bacilli in water were shown to be dependent on the rate at which the blood was diluted out. Other relevant parameters examined were background flora, pH and sunlight.
Pseudorabies and transmissible gastroenteritis : a serological survey in South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Williams, R.; Esterhuysen, J.J.; Robinson, J.T.R.; Verwoerd, Daniel Wynand
Two specific and sensitive, indirect enzyme-linked immunosorbent assays (ELISAs) utilizing a protein G-peroxidase conjugate were developed to detect antibodies to the pseudorabies virus (PRV) and the transmissible gastroenteritis virus (TGEV) in pig sera. Sera from 5,337 pigs, obtained from various abattoirs in South Africa, were tested with both ELISAs. No serological evidence of infection with either PRV or TGEV was found in any of the pigs tested.
Osteology of the pelvic limb of the African elephant (Loxodonta africana)
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Smuts, M.M.S. (Malie Marie Sophie), 1933-; Bezuidenhout, A.J. (Abraham Johannes), 1942-; Verwoerd, Daniel Wynand; Seegers, Christine D.
The pelvic girdle was characterized by large, transversely-placed ilial wings. The femur was the longest bone of the skeleton and its fovea capitis was situated caudomedially between the epiphyseal line and the articular surface of the femoral head. A wedge-shaped patella articulated with the femoral trochlea. The bones of the crus were approximately half as long as the femur and consisted of the sturdy tibia and slender fibula. The condyles of the tibia were concave and the femoro-tibial joint was congruent with rudimentary menisci. The tarsus consisted of seven bones which were arranged in three rows. There were five metatarsal bones. Only four digits were present, the third and fourth consisted of three phalanges each while the second and fourth digits were smaller and consisted of two phalanges each. The first digit was represented by one proximal sesamoid bone only. A large, cartilagenous rod or prehallux was attached to the first tarsal and metatarsal bones. Proximal sesamoid bones were present on the plantar aspect of the trochleae of metatarsal bones 1- V. The pes was found to be digitigrade and the digits rested on a thick pad of elastic connective tissue and fat.
Changes in the blood-gas status of sheep with experimentally induced heartwater
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Van Amstel, S.R.; Reyers, Fred; Myburgh, Elsbe; Verwoerd, Daniel Wynand
The blood-gas status of seven sheep with experimentally induced heartwater during the acute and terminal stages was investigated. Changes in blood gas included a decline in arterial oxygen tension (pO₂) combined with a respiratory alkalosis. Although the sheep became hypoxaemic, blood-gas changes associated with respiratory failure were not observed.
Evaluation of a short-term in vitro growth-inhibition test to determine susceptibility of Trypanosoma vivax stocks to various trypanocides
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Kaminsky, R.; Moloo, S.K.; Verwoerd, Daniel Wynand; Zweygarth, Erich
Two Trypanosoma vivax stocks were initiated in culture with tsetse or culture-derived metacyclics. They were propagated axenically as bloodstream trypomastigotes at 35°C in 4% C0₂ in air. Populations of trypanosomes were incubated with various concentrations of antitrypanosomal compounds, namely diminazene aceturate, quinapyramine sulphate, DL-α-difluoromethylornithine, isometamidium chloride, suramin and mel Cy. Growth was monitored after 24 h of incubation and the growth inhibition was calculated. All six drugs tested showed little effect upon the growth of the parasite populations. These results indicate that a 24-h growth-inhibition test was not suitable for determining the drug susceptibility of T. vivax stocks in vitro. Neither did the results correlate with those obtained with susceptible or resistant stocks of T. b. brucei, T. b. evansi or T. simiae described in the literature, or with the results of these two T. vivax stocks tested in cattle.
Guide for authors
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Anonymous; Verwoerd, Daniel Wynand
The Theiler Memorial Trust Award
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Verwoerd, Daniel Wynand; Verwoerd, Daniel Wynand
Bovine besnoitiosis : transfer of colostral antibodies with observations possibly relating to natural transmission of the infection
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Shkap, Varda; Pipano, E.; Marcus, S.; Krigel, Y.; Verwoerd, Daniel Wynand
Colostral antibodies to B. besnoiti were detected by immunofluorescence in four calves born to two Besnoitia-infected dams, with titres ranging from 1:64 to 1:1024. A specific antibody titre of 1:1024 was found in colostrum collected from one of the dams. Two of the newborn calves, when sampled immediately after birth, were serologically negative to B. besnoiti, but became positive on the next day. In all the calves, antibodies were detectable up to the age of 4 months. Observations concerning passive transfer of antibodies from Besnoitia-infected dams to offspring, and transmission of the infection among infected and non-infected closely kept cows, are discussed.
Bile enhances the infectivity of third stage larvae of Dictyocaulus filaria
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Titoy, G.A.P.; Schwan, Ernst Volker; Verwoerd, Daniel Wynand
Incubating metacyclic larvae of Dictyocaulus filaria in ovine bile solution prior to per os infection significantly enhanced their infectivity to sheep.
Epidemiology of African horsesickness : duration of viraemia in zebra (Equus burchelli)
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Barnard, B.J.H.; Bengis, Roy G.; Keet, D.F.; Dekker, E.H.; Verwoerd, Daniel Wynand
The viraemic period of African horsesickness is significantly longer in experimentally infected zebra than in horses. The virus could be isolated 40 d post-infection from blood and 48 d post-infection from spleen. The introduction of zebra into African horsesickness-free countries should therefore be considered carefully, and preferably be restricted to serologically negative zebra.
Epidemiology and control of trypanosomosis
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Chadenga, V.; Verwoerd, Daniel Wynand
Tsetse-transmitted trypanosomosis remains a major constraint to the development of agriculture, particularly to that of livestock production in sub-Saharan Africa. It is estimated that 10 million km² of Africa are tsetse infested, exposing some 50 million people and 60 million cattle to the risk of trypanosomosis. The epidemiology of the disease is complex and is greatly influenced by management and farming practices. The different control strategies are reviewed and their comparative advantages assessed. It is concluded that eradication of tsetse flies, while desirable, is rarely achieved. It is perhaps more realistic to aim for disease suppression, with vector-control campaigns linked to sustainable land-use programmes. Nevertheless, progressive tsetse eradication remains the long-term goal.
A survey of the incidence and importance of the tick-borne diseases heartwater, redwater and anaplasmosis in the heartwater-endemic regions of South Africa
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Du Plessis, J.L.; De Waal, D.T.; Verwoerd, Daniel Wynand; Stoltsz, Wilhelm Heinrich
In an almost 50% response to a survey questionnaire, farmers in the heartwater-endemic regions of South Africa indicated that they were experiencing losses of 1,3, 0,3 and 0,2% in cattle due to heartwater, redwater and anaplasmosis, respectively. In small stock, the heartwater mortality was 3,8%. Only 35% of cattle farmers and 15% of farmers keeping sheep and goats, vaccinate their animals against heartwater. It would seem that the present vaccine does not control heartwater adequately and, with 9% of farmers claiming poor protection after immunization, it would be difficult to recommend wider use of the heartwater vaccine. Likewise, vaccination against redwater and anaplasmosis on 11,8 and 14,2% of farms, respectively, appears to have had no beneficial effect on the mortality rates of these diseases. Many farmers still believe that very few or no ticks should be seen on cattle. In fact, it would appear that a considerable proportion of farmers find so few ticks on their cattle, that the frequency of acaricidal treatment is in many cases too high. Although there is no correlation between the incidence of heartwater and the intensity of tick control, there is also no serological evidence to support the possibility of an endemically unstable condition. The concept that endemic stability as a means to control heartwater in cattle can be achieved by allowing more ticks on animals, has not yet been established. The overall impression is that farmers do not regard heartwater in cattle as such a serious problem as it is generally believed to be. In small stock, however, heartwater is a severe constraint in the bushveld regions of the Transvaal and in the valley bushveld of the eastern Cape Province. In the latter, it is particularly Angora goats that are affected.
Isolation and preliminary characterization of a caprine rotavirus
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Da Costa Mendes, Vasco Manuel; De Beer, M.C.; Goosen, G.H.; Steele, Andrew Duncan; Verwoerd, Daniel Wynand
Five cytopathic rotavirus strains were isolated in MA 104 cells from stool specimens of kids with diarrhoea. Pre-treatment of the virus with trypsin and incorporation of low levels of trypsin in the maintenance medium were important for the successful cultivation of the strains in these cells. The isolates were shown to be group A rotaviruses by antigenic reactivity with a group A monoclonal antibody. This was confirmed by the migration patterns of the viral RNA genome during polyacrylamide gel electrophoresis, which also confirmed that all five strains had an identical RNA electropherotype. Analysis with monoclonal antibodies to the subgroup-specific VP6 antigen showed that these strains carried the subgroup I epitope.
Subject index
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Anonymous; Verwoerd, Daniel Wynand
Author index
(Pretoria : Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Verwoerd, Daniel Wynand
The virtual absence of Culicoides imicola (Diptera: Ceratopogonidae) in a light-trap survey of the colder, high-lying area of the eastern Orange Free State, South Africa, and implications for the transmission of arboviruses
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Meiswinkel, R.; Verwoerd, Daniel Wynand; Venter, Gert Johannes
Altogether 52 078 Culicoides biting midges of 35 species were collected during February 1990 and 1993 in 40 light-trap collections made on 17 cattle and/or sheep farms in the Bethlehem and Fouriesburg districts of the colder, high-lying eastern Orange Free State. Culicoides (Avaritia) bolitinos was by far the most abundant species, representing 50,9% of all specimens collected. Culicoides (A.) imicola, considered to be the most common stock-associated species in the summer rainfall areas of southern Africa, and the only proven vector of bluetongue virus (BTV) and African horsesickness virus (AHSV) in the subregion, was uncommon, comprising only 1,4%. While AHS is apparently absent, BT and bovine ephemeral fever (BEF) are endemic in this cooler, high-lying area of South Africa. The virtual absence of C. imicola implies that other Culicoides species, such as C. bolitinos and C. cornutus, may be involved in transmitting BT virus (and perhaps BEF) in the eastern Orange Free State, and possibly elsewhere in Africa. Virus isolation attempts made on 45 single species pools of C. bolitinos, C. pycnostictus, C. milnei, C. leucostictus, C. zuluensis and C. gulbenkiani were, however, negative. Finally, 20 of 28 blood-engorged Culicoides of 11 species, which were tested against cattle, sheep, horse, pig and bird antisera, tested only positive against cattle antisera.
A bioequivalence and pharmacokinetic evaluation of two commercial diminazene aceturate formulations administered intramuscularly to cattle
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Swan, Gerry E.; Du Preez, J.L.; Verwoerd, Daniel Wynand; Gummow, Bruce
The bioequivalence of the diminazene formulation Veriben (Centaur) was determined in cattle (n=10) by means of a single-dose, randomized cross-over experiment. The results of nine statistical procedures commonly used for bioequivalence evaluation are discussed. Veriben was found to be equivalent to Berenil (Hoechst) with respect to the area under the plasma concentration versus time curve, but not in terms of the maximum plasma drug concentration and the time to maximum plasma drug concentration. Pharmacokinetic parameters were calculated in which bioequivalence data (n=10) together with data from an additional four cattle were used. A two-compartment model best described the pharmacokinetic behaviour of diminazene in cattle. Peak concentrations of diminazene (3,24 ± 0,16μg/ml) were reached 49,8 (± 7,6) min after intramuscular injection of 3,5 mg/kg drug, with absorption proceeding rapidly (t½α=1,93 ± 0,95h). Diminazene was slowly eliminated (t½β=222 h), resulting in a mean residence time of 13,27 d. The safe interval necessary between successive treatments of diminazene or before live babesia vaccines should be administered, and a recommended pre-slaughter withdrawal period are also discussed.
The impact of nagana
(Published by the Agricultural Research Council, Onderstepoort Veterinary Institute, 1994) Connor, R.J.; Verwoerd, Daniel Wynand
The disease in cattle, called nagana in Zulu land, was linked with trypanosomal parasitaemia and tsetse flies. Nagana occurs in livestock throughout the tsetse belts of Africa. Wild animals are tolerant of trypanosomal infections. Nagana affects individual animals, herds and socio-economic development. In susceptible animals nagana may be acute, but chronic infections are more common. The host-parasite interaction produces extensive pathology and severe anaemia. Clinically affected animals lose condition and become weak and unproductive. Nagana is often fatal and, at herd level, its impact is wide ranging. All aspects of production are depressed: fertility is impaired; milk yields, growth and work output are reduced; and the mortality rate may reduce herd size. Africa has to feed its rapidly growing human population, and animal products are a vital dietary component. However, in most tsetse areas, there is not enough meat and milk. Furthermore, animal draft power is often not available, which limits cultivation and local transport. These factors lower household incomes and retard socio-economic development. Sustainable rural development requires that nagana be controlled. This in turn needs considerable resources, whichever control strategy is adopted.

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