2003 Onderstepoort Journal of Veterinary Research, Volume 70, 2003

Permanent URI for this collectionhttp://hdl.handle.net/2263/17656

Contents Pages: Onderstepoort Journal of Veterinary Research, Vol 62, 1995

CONTENTS

*Volume 70: Number 1*

Evaluation of an indirect enzyme-linked immunosorbent assay for the detection of feline lentivirus-reactive antibodies in wild felids, employing a puma lentivirus-derived synthetic peptide antigen	Van Vuuren, M, Stylianides, E, Zuckerman, EE, Hardy, WD Jr & Kania, SA	1

Studies on the genus Setaria Viborg, 1795 in South Africa. II. Setaria scalprum (Von Linstow, 1908) and Setaria saegeri (Le Van Hoa, 1961)	Boomker, JDF, Watermeyer, R & Putterill, JF	7

The morphological characteristics of the antebrachiocarpal joint of the cheetah (Acinonyx jubatus)	Groenewald, HB & Ohale, LOC	15

Comparison of complement fixation test, immunoblotting, indirect ELISA, and competitive ELISA for detecting antibodies to Mycoplasma mycoides subspecies mycoides small colony (SC) in naturally infected cattle from the 1995 outbreak in Botswana	Marobela-Raborokgwe, C, Nicholas, R, Ayling, R & Bashiruddin, JB	21

Resistance to trypanocidal drugs - suggestions from field survey on drug use in Kwale district, Kenya	Mugunieri, GL, Murilla, GA & Boomker, JDF	29

Parasites of South African wildlife. XVII. Ostertagia triquetra n. sp. (Nematoda: Trichostrongylina) from the grey rhebuck, Pelea capreolus (Forster, 1790)	Boomker, JDF & Durette-Desset, MC	37

Conditioned feed aversion as a means to prevent tulp (Homeria pallida) poisoning in cattle	Snyman, LD, Schultz, RA, Joubert, JPJ, Basson, KM & Labuschagne, L	43

Indirect enzyme-linked immunosorbent assay for the detection of antibody against Rift Valley fever virus in domestic and wild ruminant sera	Paweska, JT, Swanepoel, R, Williams, R, Cohen, AS, Grobbelaar, AA, Croft, JE, Gerdes, GH, Wright, IM, Van Dijk, AA & Smith, SJ	49

Research communications:

Isolation of Toxoplasma gondii from goats with a history of reproductive disorders and the prevalence of Toxoplasma and chlamydial antibodies	Sharma, SP, Baipoledi, EK, Nyange, JFC & Tlagae, L	65

Schistosoma mattheei - an ovum containing twin miracidia	Van Wyk, JA & Van Rensburg, LJ	69

Seroconversion in captive African wild dogs (Lycaon pictus) following administration of a chicken head bait/SAG-2 oral rabies vaccine combination	Knobel, DL, Liebenberg, A & Du Toit, JT	73


*Volume 70: Number 2*

Climate change decreases habitat suitability for some tick species (Acari: Ixodidae) in South Africa	Estrada-Pena, A	79

Clinical and pathological observations on Streptococcus sp. infection on South African trout farms with gas supersaturated water supplies	Huchzermeyer, KDA	95

Ventriculo-atrial conduction in the ovine heart, caused by premature ventricular complexes	Ker, JA & Webb, EC	107

Ixodid ticks of Angora and Boer goats, grysbok, common duikers, kudus and scrub hares in Valley Bushveld in the Eastern Cape Province, South Africa	Horak, IG & MacIvor, KM de F	113

Description and classification of abnormal cercariae of Schistosoma mattheei and a method of concentration and collection	Van Wyk, JA & Van Rensburg, LJ	121

Parasites of domestic and wild animals in South Africa. XLI. Arthropod parasites of impalas, Aepyceros melampus, in the Kruger National Park	Horak, IG, Braack, LEO, Boomker, JDF, Gallivan, GJ & De Vos, V	131

Research communications:

In vitro infection by Ehrlichia ruminantium of baby hamster kidney (BHK), Chinese hamster ovary (CHO-K1) and Madin Darby bovine kidney (MDBK) cells	Zweygarth, E & Josemans, AI	165

Effect of host age in the distribution of adult Trichinella zimbabwensis in the small intestines of golden hamsters (Mesocricetus auratus) and Balb C mice	Mukaratirwa, S, Nkulungo, E, Matenga, E & Bhebhe, E	169


*Volume 70: Number 3*

Parasites of domestic and wild animals in South Africa. XLII. Helminths of sheep on four farms in the Eastern Cape Province	Horak, IG	175

Parasites of domestic and wild animals in South Africa. XLIII. Ixodid ticks of domestic dogs and cats in the Western Cape Province	Horak, IG & Matthee, S	187

PCR-based detection of the transovarial transmission of Uruguayan Babesia bovis and Babesia bigemina vaccine strains	Nel, LH, Gayo, V, Romito, M, Solari, MA & Viljoen, GJ	197

First evidence of Anaplasma platys in Rhipicephalus sanguineus (Acari: Ixodida) collected from dogs in Africa	Sanogo, YO, Inokuma, H, Parola, P, Brouqui, P, Davoust, B & Camicas, JL	205

A comparative study on the clinical, parasitological and molecular diagnosis of bovine trypanosomosis in Uganda	Magona, JW, Mayende, JSP, Olaho-Mukani, W, Jonsson, NN, Welburn, SC, Eisler, MC & Coleman, PG	213

Continuous disinfection as a means to control infectious diseases in poultry. Evaluation of a continuous disinfection programme for broilers	Bragg, RR & Plumstead, P	219

Comparing the detection of exposure to Ehrlichia ruminantium infection on a heartwater-endemic farm by the pCS20 polymerase chain reaction assay and an indirect MAP1-B enzyme linked immunosorbent assay	Simbi, BH, Peter, TF, Burridge, MJ & Mahan, SM	231

Use of rapid rural appraisal and cross-sectional studies in the assessment of constraints in smallholder cattle production systems in the western Kenya highlands	Okuthe, OS, McLeod, A, Otte, JM & Buyu, GE	237

Detection of antibodies to the Ehrlichia ruminantium MAP1-B antigen in goat sera from three communal land areas of Zimbabwe by an indirect enzyme-linked immunosorbent assay	Kakono, O, Hove, T, Mahan, S & Geysen, D	243

Research communication:

Fleas of elephant shrews (Mammalia, Macroscelididae) and a new host and locality record for Macroscelidopsylla albertyni De Meillon & Marcus, 1958 (Siphonaptera, Chimaeropsyllidae)	Horak, IG, Fourie, LJ & Beaucournu, JC	251


*Volume 70: Number 4*

Leishmania donovani-derived lipophosphoglycan plus BCG induces a Th1 type immune response but does not protect Syrian golden hamsters (Mesocricetus auratus) and BALB/c mice against Leishmania donovani	Tonui, WK, Mpoke, SS, Orago, AS, Turco, SJ, Mbati, PA & Mkoji, GM	255

Seasonal evolution of faecal egg output by gastrointestinal worms in goats on communal farms in eastern Namibia	Kumba, FF, Katjivena, H, Kauta, G & Lutaaya, E	265

Molecular analysis of bovine viral diarrhoea virus isolates from South Africa	Kabongo, N, Baule, C & Van Vuuren, M	273

General morphology of the oral cavity of the Nile crocodile, Crocodylus niloticus (Laurenti, 1768). I. Palate and gingivae	Soley, JT & Putterill, JF	281

The heart remembers: observations of cardiac memory in the Dorper sheep heart	Webb, EC, Ker, JA & Bekker, PA	299

Review of blackfly (Diptera: Simuliidae) control in South Africa	Myburgh, E & Nevill, EM	307

Occurrence, clinical manifestation and the epidemiological implications of naturally occurring canine trypanosomosis in western Kenya	Matete, GO	317

Population structure of Argas arboreus (Acari: Argasidae) ticks associated with seasonally abandoned mixed heronries, dominated by cattle egrets (Bubulcus ibis), in South Africa	Belozerov, VN, Van Niekerk, DJ & Butler, HJB	325

Author index		331

Subject index		341

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Now showing 1 - 20 of 39

Population structure of Argas arboreus (Acari: Argasidae) ticks associated with seasonally abandoned mixed heronries, dominated by cattle egrets (Bubulcus ibis), in South Africa
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Belozerov, V.N.; Van Niekerk, D.J; Butler, H.J.B.; Boomker, Jacob Diederik Frederik
During winter populations of Argas arboreus from heronries of the cattle egret, Bubulcus ibis, in South Africa are composed of adults, with some predominance of males, and II-IV instar nymphs, in a state of diapause. The period of tick activity, including reproduction and development of eggs, larvae and N₁ nymphs, is synchronized with the nesting and breeding season of their avian hosts. It begins during spring with the return of birds to the heronry, and ceases in autumn through induction of reproductive diapause in engorged females, and behavioural diapause in unfed nymphs and adult ticks. Many ticks showed morphological anomalies and malformations, the study of which could possibly be used for monitoring of environmental pollution.
Seroconversion in captive African wild dogs (Lycaon pictus) following administration of a chicken head bait/SAG-2 oral rabies vaccine combination
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Liebenberg, A.; Du Toit, J.T.; Boomker, Jacob Diederik Frederik; Knobel, Darryn Leslie
This study determined the proportion of captive juvenile and adult African wild dogs (Lycaon pictus) that developed protective titres of rabies neutralising antibodies following ingestion of a chicken head bait/SAG-2 oral rabies vaccine combination. A single chicken head containing 1.8 ml of SAG-2 vaccine (10⁸˙⁰ TCID₅₀/ml) in a plastic blister was fed to each of eight adult and three juvenile wild dogs. Bait ingestion resulted in a significant rise in serum neutralising antibody titres. Overall seroconversion rate was eight out of 11 (72.7 %), and all the puppies and five out of eight (62.5 %) adults showed potentially protective levels of antibodies on day 31. The mean post-vaccination neutralising antibody titre was within the range reported to be protective against challenge with virulent rabies virus in other species.
The heart remembers : observations of cardiac memory in the Dorper sheep heart
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Bekker, P.A .; Boomker, Jacob Diederik Frederik; Webb, E.C. (Edward Cottington); Ker, James A.
Memory is a property common to a diverse range of tissues. Cardiac memory has been demonstrated in the human, dog, rat and rabbit. This is a peculiar phenomenon reflected in the T wave of the electrocardiogram. The heart is able to remember periods of alterations in the sequence of ventricular activation and once there is a return to a normal sequence of ventricular activation the T waves may manifest memory. Cardiac memory is noted when the T wave during normal ventricular activation retains the vector of the previous abnormal QRS complex, caused by a period of altered ventricular activation. Possible mechanisms of memory in the heart are alterations of the transient outward potassium current (Iᵼ₀) in ventricular myocytes and new protein synthesis inside myocytes. These two mechanisms operate in short- and long-term cardiac memory respectively. Currently, it is unknown whether memory may have adverse structural consequences in the heart. We were able to demonstrate memory in the hearts of Dorper wethers and this is the first report of cardiac memory in Dorper sheep.
Molecular analysis of bovine viral diarrhoea virus isolates from South Africa
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Kabongo, N.; Baule, C.; Boomker, Jacob Diederik Frederik; Van Vuuren, Moritz
The presence of bovine viral diarrhoea virus in South Africa has been confirmed by several serological surveys. However, little is known about its biological properties. Twenty five isolates obtained by isolation in tissue culture and detected by means of the antigen capture ELISA from clinically sick cattle and from foetal calf serum in South Africa were characterized on the basis of analysis of the 5' non-translated (NTR) region of the genome. A reverse-transcription polymerase chain reaction (RT -PCR) was used to amplify specific sequences from the 5'NTR of the genome. The oligonucleotide primers corresponding to positions 105-125 and 399-378, respectively, in the sequence of BVDV strain NADL were used to generate the PCR products. Both strands were sequenced directly with these primers and fluorescence-labelled dideoxynucleotides in an automated nucleic acid sequencer. Reference strains of pestiviruses [(BVDV type I, BVDV type II, border disease virus (BDV) and hog cholera virus (HCV)] and isolates from a previous investigation on BVDV in southern Africa were included for comparative purposes. All the BVDV strains obtained during this study belong to subgroups of BVDV genotype I. No association could be demonstrated between the geographic origin of the isolates. A number of isolates formed another branch separate from the existing branches la, Ib and Ic. These findings suggest that extensive genetic diversity can be found within BVDV type I isolates from southern Africa. Isolates that group with the classical BVDV type I strains, particularly of American origin, coexist with variants that appear to represent a local genetic pool and or variants evolving from the classical strains.
Detection of antibodies to the Ehrlichia ruminantium MAP1-B antigen in goat sera from three communal land areas of Zimbabwe by an indirect enzyme-linked immunosorbent assay
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Kakono, O.; Hove, T.; Mahan, S.; Geysen, Dirk; Boomker, Jacob Diederik Frederik
A total of 1 286 caprine serum samples collected from three communal land areas in Zimbabwe from March 1999 to February 2000 were tested for Ehrlichia ruminantium antibodies using the indirect MAP1-B enzyme-linked immunosorbent assay. Of the 480 samples tested from Mudzi, a non-heartwater area, 425 (89.4%) were positive. In the heartwater endemic areas, of the 441 samples 352 (79.4 %) from Gwanda and 300 of the 365 samples (83.2 %) from Bikita tested positive. The seroprevalence in the Bikita and Gwanda (approaching 90 %) is consistent with reports in related serological surveys that puts the seroprevalence of E. ruminantium in goats from endemic areas of Zimbabwe at 90 %. However, the high seroprevalence in the non-heartwater area of Mudzi is unexpected and can be a result of the presence of a serologically cross-reacting organism, which has to be isolated and characterized. The results need to be confirmed by alternative tests based on molecular diagnostic tools. There were no significant differences in seroprevalence between the three sampling areas as there were between the three sampling periods. The highest corresponded with the period January to February (peak tick activity) and the lowest with the period July to September (minimal tick activity).
A comparative study on the clinical, parasitological and molecular diagnosis of bovine trypanosomosis in Uganda
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Magona, Joseph W.; Mayende, J.S.P.; Olaho-Mukani, W.; Jonsson, N.N.; Welburn, S.C.; Eisler, M.C.; Coleman, P.G.; Boomker, Jacob Diederik Frederik
The clinical, parasitological and molecular diagnosis of bovine trypanosomosis were compared using samples from 250 zebu cattle exposed to natural trypanosome challenge in Uganda. Clinical examination, molecular and parasitological diagnoses detected 184 (73.6%), 96 (38.4 %) and 36 (14.4%) as diseased, respectively. The sensitivity and specificity of clinical examination were 87.5% and 35%, and 78 % and 27 % based on molecular and parasitological diagnoses, as gold standards, respectively. Of the 33, 3, 13 and 12 parasitological-positive cattle that had Trypanosoma brucei, Trypanosoma congolense, Trypanosoma vivax or mixed infections, 78 %, 33 %, 84 % and 100% respectively manifested clinical signs. Of the 24, 89, 12 , 3, 6 and 27 cattle detected by molecular diagnosis to have mixed infections, T. brucei, T. vivax, T. congolense forest-, Savannah- and Tsavo-type, 100%, 83%, 91 %, 100%, 67% and 81 % had clinical signs, respectively. In conclusion, treatment of cattle based on clinical examination may clear up to 87.5% or 78% of the cases that would be positive by either molecular or parasitological diagnosis, respectively. Under field conditions, in the absence of simple and portable diagnostic tools or access to laboratory facilities, veterinarians could rely on clinical diagnosis to screen and treat cases of bovine trypanosomosis presented by farmers before confirmatory diagnosis in diagnostic centres for few unclear cases is sought.
First evidence of Anaplasma platys in Rhipicephalus sanguineus (Acari: Ixodida) collected from dogs in Africa
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Sanogo, Y.O.; Inokuma, H.; Parola, P.; Brouqui, P.; Davoust, B.; Camicas, J-L.; Boomker, Jacob Diederik Frederik
A total of 27 ticks, comprising Rhipicephalus sanguineus (Latreille) (n = 21), Haemaphysalis leachi (Andouin) (n = 4) and Haemaphysalis paraleachi (Camicas, Hoogstraal & EI Kammah) (n = 2) were recovered from two clinically healthy female dogs in the Democratic Republic of the Congo. DNA of Anaplasma platys was detected in a female R. sanguineus, using primers derived from the 16S rRNA gene, which amplify members of the family Anaplasmataceae. Anaplasma platys DNA was also detected in the blood of one of the dogs. Phylogenetic analysis based on partial sequences of the 16S rRNA, the gItA and the groEL genes ranged the detected agent within the Anaplasma clade. This is the first reported detection of A. platys in ticks in Africa. This finding raises the question of the possible involvement of R. sanguineus in A. platys infection of dogs.
Use of rapid rural appraisal and cross-sectional studies in the assessment of constraints in smallholder cattle production systems in the western Kenya highlands
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Okuthe, O.S.; McLeod, A.; Otte, J.M.; Buyu, G.E.; Boomker, Jacob Diederik Frederik
Assessment of livestock production constraints in the smallholder dairy systems in the western Kenya highlands was carried out using both qualitative and quantitative epidemiological methods. Rapid rural appraisals (qualitative) were conducted in rural and peri-urban areas. A cross-sectional survey (quantitative) was then conducted on a random sample of farms in the study area. Diseases, poor communication, lack of marketing of livestock produce, lack of artificial insemination services and feed and water shortages during the dry season were identified as the major constraints to cattle production in both areas. Tick borne diseases (especially East Coast fever) were identified as the major constraint to cattle production. Qualitative methods were found to be more flexible and cheaper than the quantitative methods by a ratio of between 2.19-2.0. The two methods were found to complement each other. Qualitative studies could be applied in preliminary studies before initiating more specific follow up quantitative studies.
Leishmania donovani-derived lipophosphoglycan plus BCG induces a Th1 type immune response but does not protect Syrian golden hamsters (Mesocricetus auratus) and BALB/c mice against Leishmania donovani
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Tonui, W.K.; Mpoke, S.S.; Orago, A.S.; Turco, S.J.; Mbati, P.A.; Mkoji, G.M.; Boomker, Jacob Diederik Frederik
The efficacy of Leishmania donovani-derived lipophosphoglycan (LPG) plus Mycobacterium bovis Bacille Calmette-Guerin (BCG) as a vaccine candidate against visceral leishmaniosis in susceptible BALB/c mouse and Syrian golden hamster (Mesocricetus auratus) models was investigated. Following a triple vaccination with a total dose of 150 µI BCG plus 60 µg or 30 µg of LPG for hamsters and BALB/c mice respectively, there were no noticeable side effects both locally and systemically; implying that the molecule was safe at this dosage level. Vaccinated animals demonstrated an activation of both the humoral as well as cell-mediated responses to LPG, which correlated with resistance against the disease. Protection by LPG plus BCG, was however, poor as the remaining immunized animals showed disease progression leading to severity of the disease as illustrated by emaciation, mass loss and heavy splenic parasitaemia in hamsters. These data nevertheless suggest that it may be rewarding to further evaluate the potential of LPG as a vaccine candidate in leishmaniosis using other adjuvants, which may enhance its immunogenicity.
Comparing the detection of exposure to Ehrlichia ruminantium infection on a heartwater-endemic farm by the pCS20 polymerase chain reaction assay and an indirect MAP1-B enzyme linked immunosorbent assay
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Simbi, B.H.; Peter, T.F.; Burridge, M.J.; Mahan, S.M.; Boomker, Jacob Diederik Frederik
Detection of heartwater is not always easy especially because all the serological assays so far available either have poor sensitivity or specificity. The indirect MAP-1B ELISA has been reported to be the most specific test for heartwater, although it does also detect antibodies to some closely related ehrlichial agents. This study was undertaken to compare two methods for the detection of heartwater infection caused by the ehrlichial agent Ehrlichia (Cowdria) ruminantium. Fifteen cattle on a heartwater-endemic farm infested with high numbers of Amblyomma hebraeum ticks, and hence exposure to E. ruminantium infection were monitored over an 8-week period by pCS20 PCR and an indirect MAP-1B ELISA. Infection was detected by pCS20 PCR in most animals with the highest number of positives (60%) in week 6 of the study. Similarly, exposure to E. ruminantium was detected by indirect MAP-1B ELISA in some animals, with the highest number of seropositives (27%) at weeks 2 - 6 of the study. The data demonstrated a fluctuating rickettsaemia in cattle in a heartwater-endemic area. Comparison of the two tests indicated that the pCS20 PCR assay was more reliable because it detected more infections than the indirect MAP-1B ELISA and would therefore be the method of choice for detection of E. ruminantium infection.
Author index
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) None; Boomker, Jacob Diederik Frederik
Occurrence, clinical manifestation and the epidemiological implications of naturally occurring canine trypanosomosis in western Kenya
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Matete, G.O.; Boomker, Jacob Diederik Frederik
Domestic dogs were screened for Trypanosoma brucei infection using the haematocrit centrifugation technique as part of routine active surveillance exercises in the Busia and Teso districts of Kenya. The purpose was to assess the role of dogs as sentinels for the occurrence of human sleeping sickness. Out of 200 dogs screened, five were found to be infected at the various test sites. These five succumbed to the disease within four weeks, and exhibited a distinct and pronounced corneal opacity before death. Blood from two naturally infected dogs were tested for the presence of the serum resistance associated (SRA) gene and one tested positive, confirming it as human infective (T. brucei rhodesiense) prevalence (0.5 %). It is considered that the occurrence of this clinical sign could be used as an early warning prediction of future outbreaks. This type of prediction could form an integral part of an indigenous technical knowledge set in areas lying at the edges of the tsetse (Glossina) belts where T. brucei is the main trypanosome species that affects dogs. The occurrence of corneal opacity in dogs could indicate a rise in the levels of T. brucei a proportion of which could be human infective T. b. rhodesiense circulating in the population early enough before disease outbreak occurs. It is thought that during sleeping sickness epidemics the domestic dog will be the first casualty rapidly succumbing to disease long before it is noticed in man. Prompt prediction of disease outbreaks would thus enable early interventions that would reduce the morbidity, mortality and the general economic losses associated with sleeping sickness to be instituted.
Continuous disinfection as a means to control infectious diseases in poultry. Evaluation of a continuous disinfection programme for broilers
(Pretoria : Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the University of Pretoria, Faculty of Veterinary Science, 2003) Bragg, R.R. (Robert Richard); Plumstead, Peter; Boomker, Jacob Diederik Frederik
A full continuous disinfection programme, consisting of disinfection during cleanout of poultry houses prior to placement of chickens, disinfection of the drinking water and spray disinfection of the birds during production was evaluated in broilers under experimental condition as well as under field conditions. Under controlled conditions, the experimental design consisted of three groups, two of which were control groups. Each group comprised 300 chickens. In one of the control groups, no disinfection of the pens was undertaken prior to the placement of the chickens. In the other control group, disinfection of the pens prior to placement of the birds was carried out using a glutaraldehyde-based product. In the test group, disinfection prior to placement was done. The drinking water of these birds was treated continuously and the birds were sprayed with a non-toxic disinfectant during production. Production parameters, such as growth rate, feed conversion ratio and feed consumption, of the birds in the three groups were monitored. In addition, all mortalities in the different groups were recorded and classified into diseases of an infectious nature, non-infectious nature and unknown category. Bacterial counts were also done on a weekly basis from the different pens. In this experiment, it was shown that the full continuous disinfection programme resulted in a lower number of mortalities caused by infectious agents as well as a reduction in the bacterial counts in the pens treated with the full continual disinfection programme. The full continuous disinfection programme was also tested on a commercial poultry farm in the Northern Cape Province of South Africa. Two production houses of 3 500 birds were randomly selected as test houses for the full continuous disinfection programme. Another similar house, which received day-old chicks from the same batch as the other two houses, was selected as the control house; it received the routine disinfection procedure prior to placement of the chicks. During the course of this experiment, a severe outbreak of Newcastle disease was experienced on this farm. It was demonstrated that, in the face of this severe challenge, the full continuous disinfection programme controlled the spread of the disease in both the houses where it had been applied at a stage when in every other house (including the control house) on the farm birds were suffering very high mortalities.
PCR-based detection of the transovarial transmission of Uruguayan Babesia bovis and Babesia bigemina vaccine strains
(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003) Gayo, V.; Romito, M.; Solari, M.A.; Viljoen, Gerrit Johannes; Boomker, Jacob Diederik Frederik; Nel, Louis Hendrik
Bovine babesiosis is responsible for serious economic losses in Uruguay. Haemovaccines play an important role in disease prevention, but concern has been raised about their use. It is feared that the attenuated Babesia bovis and Babesia bigemina vaccine strains may be transmitted by the local tick vector Boophilus microplus, and that reversion to virulence could occur. We therefore investigated the possibility that these strains could be transmitted via the transovarial route in ticks using a Babesia species-specific polymerase chain reaction (PCR) assay. DNA was extracted from the developmental stages of the tick vector that had fed on calves immunized with the haemovaccine. It was possible to detect Babesia DNA not only in adult ticks, but also in their eggs and larvae. In addition, it was shown that calves infested with larvae derived from eggs laid by ticks fed on acutely infected calves, were positive for Babesia using PCR. Caution should therefore be shown with the distribution of the haemovaccine in marginal areas. It is still advisable that suitable tick control measures be used to prevent transovarial transmission and the potential risk of attenuated Babesia reverting to virulence.
Fleas of elephant shrews (Mammalia, Macroscelididae) and a new host and locality record for Macroscelidopsylla albertyni De Meillon & Marcus, 1958 (Siphonaptera, Chimaeropsyllidae)
(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003) Fourie, L.J.; Beaucournu, J-C.; Boomker, Jacob Diederik Frederik; Horak, Ivan Gerard
Fleas collected from the elephant shrews Elephantulus edwardii (A. Smith, 1839) in the Western Cape Province, Elephantulus myurus Thomas & Schwann, 1906 in Free State Province, and an Elephantulus of undetermined species in the Eastern Cape Province, South Africa are recorded in this paper. Five flea species were recovered of which Demeillonia granti (Rothschild, 1904) was the most numerous and prevalent. It was followed by Macroscelidopsylla albertyni De Meillon & Marcus, 1958, collected only from E. edwardii. Both this elephant shrew and the locality are new records for M. albertyni. Chiastopsylla octavii (Rothschild, 1904), Listropsylla agrippinae (Rothschild, 1904), and a female flea of the Ctenocephalides felis group were accidental infestations. The sex ratio of D. granti was 0.86 on both male and female elephant shrews, while that of M. albertyni on E. edwardii was 0.83.
Subject index
(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003) None; Boomker, Jacob Diederik Frederik
Seasonal evolution of faecal egg output by gastrointestinal worms in goats on communal farms in eastern Namibia
(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003) Kumba, F.F.; Katjivena, H.; Kauta, G.; Lutaaya, E.; Boomker, Jacob Diederik Frederik
As a more detailed continuation of a previous study, faecal samples for worm egg counts were collected per rectum from ten marked adult animals in selected flocks of goats, in each of six villages evenly spread out in the communal farming district of Okakarara in eastern Namibia. The study was conducted on a monthly basis from August 1999 to July 2000. Average faecal worm egg counts (FECs) were highest during the warm-wet season, much lower during the cold-dry months and moderate during the hot-dry season. Least square means of FECs were 2140, 430 and 653 per gram of faeces for the three seasons, respectively. Seasonal variation in egg counts was significant (P <0.0001). Gastrointestinal strongyles, and to a lesser extent Strongyloides species, were the predominant parasite groups identified in goats. Kidding rates peaked in the cold-dry season and mortality rates in the hot-dry season. Results of this study suggest that gastrointestinal parasitism may be a problem that accentuates the effect of poor nutrition on small ruminants during the season of food shortages in the east of Namibia and that the use of FECs per se to assess the severity of gastrointestinal parasitic infection in goats followed by chemoprophylactic strategic and/or tactical treatment, may not be the best approach to addressing the worm problem under resource-poor conditions. The use of the FAMACHA© system that identifies severely affected animals for treatment is technically a better option for communal farmers.
Review of blackfly (Diptera: Simuliidae) control in South Africa
(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003) Myburgh, E.; Nevill, E.M.; Boomker, Jacob Diederik Frederik
The medical, veterinary and economic importance of blackflies in South Africa, and the historical development of blackfly control programmes in various South African rivers, are reviewed in this paper. In 1996 it was estimated that blackflies can cause more than R 88 million damages per annum along the middle and lower Orange River where Simulium chutteri is considered the main pest species. A clear link between the construction of dams and the spread of the blackfly problem was shown. Four phases characterize the development of blackfly control in South Africa: (1) during the 1960s blackflies in the Vaal River were controlled with DDT; (2) during the 1970s and into the 1980s blackflies were controlled using water-flow manipulation; (3) when used at strategic times, water-flow manipulation could be used to enhance the effect of natural predator populations; and (4) during the 1990s the organophosphate temephos and toxins produced by the bacterium Bacillus thuringiensis var. israelensis were tested for their efficacy against blackflies. The larvicides temephos and B. thuringiensis proved to be effective and are still used in several control programmes. The latest research focuses on the factors that influence adult blackfly survival and annoyance, as well as the development of methods that can be used to protect sheep from blackfly attacks.
General morphology of the oral cavity of the Nile crocodile, Crocodylus niloticus (Laurenti, 1768). I. Palate and gingivae
(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003) Putterill, John Fraser; Boomker, Jacob Diederik Frederik; Soley, John Thomson
The heads of nine 2.5 to 3-year-old Nile crocodiles (Crocodylus niloticus) were obtained from a commercial farm where crocodiles are raised for their skins and meat. The animals from which these specimens originated were clinically healthy at the time they were slaughtered. A detailed description of the macroscopic and microscopic features of the palate and gingivae of the Nile crocodile is presented and the results are compared with published information on this species and other Crocodylia. The histological features are supplemented by information supplied by scanning electron microscopy. Macroscopic features of interest are the small conical process situated at the base of the first two incisors of the maxilla, the distribution of cobbled units on the palate, and the broad dentary shelf forming the rostral aspect of the mandible. Histologically the palate and gingivae did not differ significantly from each other and both regions showed a presence of Pacinian-type corpuscles. Two types of sensory structures (taste receptors and pressure receptors) were identified in the regions examined, both involving modification of the epithelium and the underlying connective tissue.
Parasites of domestic and wild animals in South Africa. XLIII. Ixodid ticks of domestic dogs and cats in the Western Cape Province
(Published jointly by the Agricultural Research Council, ARC-Onderstepoort Veterinary Institute and the Faculty of Veterinary Science, University of Pretoria., 2003) Matthee, Sonja; Boomker, Jacob Diederik Frederik; Horak, Ivan Gerard
Ticks were collected at monthly intervals for 16 consecutive months from individual dogs by their owners in or close to the town of Stellenbosch, Western Cape Province. They were also collected for 27 consecutive months from dogs presented for a variety of reasons at three veterinary clinics in Stellenbosch, and from dogs upon admission to an animal welfare shelter. At one of the veterinary clinics ticks were also collected from cats. Dog owners collected six ixodid species from their pets and the most numerous of these were Haemaphysalis leachi and Rhipicephalus gertrudae. Twelve ixodid tick species and the argasid tick, Otobius megnini were collected from dogs at veterinary clinics and the animal shelter, and H. leachi, R. gertrudae and Rhipicephalus sanguineus were the most numerous. A total of nine dogs were infested with the Karoo paralysis tick, Ixodes rubicundus. No clear pattern of seasonality was evident for H. leachi, which was present throughout the year. The largest numbers of adult R. gertrudae were generally present from August to October, while adult R. sanguineus were collected during October 2000, February and March 2001, from January to April 2002 and during October 2002. Five ixodid tick species, of which H. leachi was the most numerous and prevalent, were collected from cats.

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