The most important tick-borne diseases (TBDs) occurring in Zambia that affect domestic animals, particularly cattle and small ruminants, are theileriosis (East Coast fever and Corridor disease), anaplasmosis (gall sickness), babesiosis (red water), and heartwater (cowdriosis). Of these, theileriosis is the most important, causing significantly more deaths than the other tick-borne diseases combined. Despite their importance, little is known about the occurrence and prevalence of haemoparasites in cattle in the communal areas of Zambia. Clinical signs and post mortem lesions are pathognomonic of mixed tick-borne infections especially babesiosis, anaplasmosis and East Coast fever (ECF). The main objective of this study was, therefore, to screen selected communal herds of cattle for tick-borne haemoparasites and identify the tick vectors associated with the high cattle mortalities due to suspected TBDs in the local breeds of cattle grazing along the banks of the Chambeshi River in Mungwi, Zambia. East Coast fever is endemic to the district of Mungwi, Northern Province, Zambia and vector control using acaricides has proved to be very costly for the small scale farmers. Also, Mungwi experiences increased cattle mortalities between December to March and May to July. All age groups of cattle are affected. A total of 299 cattle blood samples were collected from July to September 2010 from Kapamba (n=50), Chifulo (n=102), Chisanga (n=38), Kowa (n=95) and Mungwi central (n=14) in the Mungwi District, Northern Province, Zambia. Ticks were also collected from the sampled cattle from April to July 2011. DNA was extracted and the parasite hypervariable region of the small subunit rRNA gene was amplified and subjected to the reverse line blot (RLB) hybridization assay. The results of the RLB assay revealed the presence of tick-borne haemoparasites in 259 samples occurring either as single or mixed infections. The most prevalent species present were the benign Theileria mutans (54.5%) and T. velifera (51.5%). Anaplasma marginale (25.7%), Babesia bovis (7.7%) and B. bigemina (3.3%) were also detected in the samples. Nine percent of the samples tested negative for the presence of haemoparasites. In a number of samples (4%) the PCR products failed to hybridize with any species-specific probes but hybridized only with the genus-specific probes which could suggest the presence of a novel species or variant of a species. Of the four Theileria species known to occur in Zambia (T. parva, T. mutans, T. velifera and T. taurotragi), T. parva is the most economically important, causing Corridor disease in the Southern, Central, Lusaka and the Copper-belt provinces, while causing ECF in the Northern and Eastern provinces of Zambia. In our study, only one sample (from Kapamba) tested positive for the presence of T. parva. This was an unexpected finding; also because the tick vector, Rhipicephalus appendiculatus, was identified on animals from Kowa (14%), Chisanga (8.5%), Chifulo (6%) and Kapamba (1.4%). We can only speculate that the RLB hybridization assay may not have been able to detect the parasite in the animals sampled due to a too low parasitaemia. The samples should also be subjected to the T. parva specific real-time PCR assay to determine a more accurate T. parva prevalence in cattle in the Mungwi district, Northern Province. In Zambia, Babesia bovis and B. bigemina are recognized as being of economic importance in cattle. In our study, B. bovis was present in 7.7% of the sampled animals and B. bigemina in 3.3% of the animals. We detected B. bovis in all of the five sampled areas with the highest detection in Mungwi central (14.3%) and Kowa (10.5%). As expected, the tick vector Rhipicephalus (Boophilus) microplus was identified from animals from all of these areas. Babesia bigemina was only reported from Kowa (10.5%). The most abundant ticks identified from the sampled animals from Kowa were Rhipicephalus (Boophilus) decoloratus (36.3%) and Rhipicephalus (Boophilus) microplus (8.8%). These tick vectors have been implicated in the transmission of B. bigemina. Our findings are in concordance with results obtained by other authors who have speculated that an increase in the detection of B. bovis may indicate that B. bovis is becoming endemic in this part of the country. This could be due to uncontrolled movement of cattle that frequently occurs within Zambia. Heartwater (cowdriosis) is caused by Ehrlichia ruminantium, a rickettsial disease that affects domestic and wild ruminants. In Zambia, heartwater is mainly a disease of cattle, although outbreaks in sheep and goats have been reported and recorded. In our study, only one sample (from Kapamba) tested positive for the presence of E. ruminantium even though Amblyomma variegatum ticks were identified from 52.9% of the sampled animals from all study areas. The cattle sampled in our study are not regularly dipped and no game has been spotted in cattle grazing areas. It is possible that these cattle may have attained a state of endemic stability to heartwater. It is also possible that the RLB hybridization assay may not have been sensitive enough to detect E. ruminantium infections if the parasitaemia was very low. Samples should also be subjected to the E. ruminantium-specific pCS20 real-time PCR assay to determine more accurately the E. ruminantium prevalence in cattle in the Mungwi district, Northern Province. Anaplasma marginale (the causative agent of bovine anaplasmosis) has previously been shown to be present in all the provinces of Zambia and is the only Anaplasma species of importance to cattle in Zambia. In our study, 25.7% of the sampled cattle tested positive for A. marginale; it was detected in all areas except Chisanga. Amblyomma variegatum was identified from 52.9% of the sampled cattle, and Rhipicephalus (Boophilus) microplus from 12.1% of the cattle. Rhipicephalus (Boophilus) microplus has been incriminated as being a vector of A. marginale. Furthermore, three samples (from Kowa) tested positive for the presence of Anaplasma centrale. To our knowledge, no vaccination regime using A. centrale is being conducted in the Mungwi district of Zambia. The presence of A. centrale is, therefore, an interesting finding. The results of our study suggest that the cause of cattle mortalities in Mungwi during the winter outbreaks is mainly due to A. marginale, B. bovis and B. bigemina infections. This was confirmed by the results of the RLB hybridization assay, clinical manifestation of the disease in the affected cattle (own observation) and the tick species identified on the animals. It appears that in Mungwi, babesiosis due to B. bovis mostly infects cattle above one year of age. Calves appear to be less affected by B. bovis infection. There is need for further epidemiological surveys in Mungwi district, Northern Province, Zambia to get a better understanding of the epidemiology of these tick-borne haemoparasites affecting cattle. We conclude that integrated control policies should be developed to take account of multi-species pathogen communities that are commonly associated with clinical and sub-clinical TBD infections in Zambia. / Dissertation (MSc)--University of Pretoria, 2012. / Veterinary Tropical Diseases / unrestricted

Malignant catarrhal fever (MCF), a disease that is usually fatal in cattle, is caused by two distinct but related bovine herpesviruses which are members of the genus Macavirus. The wildebeest-associated alcelaphine herpesvirus-1 (AlHV-1) occurs mainly in East and southern Africa, whereas the sheep-associated ovine herpesvirus-1 (OvHV-2) has an almost worldwide distribution. The natural hosts or carriers of these two viruses are subclinically infected. The 130 kilobase pair (kbp) AlHV-1 double stranded DNA genome consists of 18 open reading frames (ORFs) coding for structural proteins and approximately 50 ORFs coding for non-structural proteins. The 18 structural ORFs encode for 4 capsid proteins, 5 tegument proteins, 8 glycoproteins and a minor capsid scaffold protein. ORF8 encoding for glycoprotein B, is the most conserved of the proteins amongst gammaherpesviruses, whereas the minor capsid protein encoded by ORF65, is amongst the most variable. Thus, the minor capsid protein is one of the antigens of choice for the development of an ELISA for detection of AlHV-1 reactive antibodies and glycoprotein B could be of importance in developing a cross-protective vaccine for gammaherpesviruses. The naming and annotation of most of the AlHV-1 ORFs is based on comparison with related gammaherpesviruses and bioinformatics. Most of these ORFs are putative as there is no direct experimental evidence confirming that they code for any particular protein. In order to investigate whether the ORFs code for any proteins, two ORFs were targeted for in vitro heterologous expression. AlHV-1, isolate C500, was grown in fetal bovine turbinate (BT) cell culture and viral genomic DNA extracted. ORF8, the putative glycoprotein B, was amplified with a PCR assay and inserted into a mammalian expression vector, pCI. VERO cells were transfected with the recombinant vector. Expression of ORF8 was confirmed by an indirect immunofluorescence assay (IFA) with AlHV-1 polyclonal sera and rabbit anti-bovine IgG (whole molecule) FITC conjugate. Truncated forms of ORF8 were further expressed as baculovirus recombinants using the Bac-to-Bac baculovirus expression system. Expression of the truncated ORF8 was confirmed by SDS-PAGE and Western blot. AlHV-1 ORF65, the minor capsid protein gene, was amplified with a PCR assay from the viral genomic DNA and cloned in frame with a histidine tag in a bacterial expression vector, pCOLD I. Expression of the minor capsid protein was confirmed by SDS-PAGE and Western blot with the histidine tag monoclonal as well as AlHV-1 polyclonal sera. Orf65 was expressed in large quantities and column purified using the histidine tag. Orf65 was also expressed as a baculovirus recombinant using the Bac-to-Bac baculovirus expression system. Expression of the protein was confirmed by SDS-PAGE and Western blot with the histidine tag and AlHV-1 polyclonal sera. ORF65 expression in the baculovirus Bac-to-Bac expression system was up-scaled and the expressed protein column purified. Antibodies raised in chicken against the purified antigen were used successfully in an indirect immunoassay to detect AlHV-1 infected cells. An indirect enzyme-linked immunosorbent assay (ELISA) to detect antibodies against AlHV-1 was developed. It is based on the use of the AlHV-1 minor capsid protein as the capture antigen for antibodies. The primary antibodies are detected by the addition of enzymelabelled (horseradish peroxidase) protein G which detects bovid, ovid and wildebeest antibodies. Addition of a substrate of the enzyme, in this case, 3,3’,5,5’- tetramethylbenzidine (TMB), results in a colour reaction which is measured using spectrophotometric procedures. At a selected cut-off point of 18, the ELISA test has a sensitivity of 100% and a specificity of 100% and has been shown to detect AlHV-1 antibodies in cattle and wildebeest. The ELISA showed no cross-reactivity with sera raised in cattle against related viruses such as ovine herpesvirus 2, bovine herpesvirus 1, 2 and 4. The two expressed proteins used in this study were found to be amongst the antigens expressed in cattle suffering from malignant catarrhal fever. The experimental AlHV-1 indirect ELISA needs further validation and this research may be extended to determine the performance of these antigens as candidate subunit vaccines. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Veterinary Tropical Diseases / unrestricted

During March 2008 a suspected outbreak of Rift Valley fever was reported on a farm in the Bela-Bela area, Limpopo Province of South Africa. The affected dairy farm, where no vaccination programme against RVF were practiced, applies an intensive farming system with 300 Holstein Friesland cattle (calves included) as well as 200 Pedi sheep on the farm. Seven calves died on this farm but no apparent clinical disease was reported in cattle as well as in sheep. During the outbreak blood samples from cattle and sheep were taken and the animals were re-sampled 8 weeks later. A set of sera was also collected from cattle on a neighbouring farm. The aim of the study was to determine the extent of the outbreak by evaluating if the virus had also infected other animals on the affected farm as well as on a neighbouring farm. During the first blood collection 233 samples were taken from cattle and 73 from sheep on the affected farm; 55 blood samples were taken from cattle on a neighbouring farm. A second blood collection was only done on the affected farm and 234 cattle and 85 sheep were bled. All the sera collected were tested by an IgM-capture ELISA and by an indirect IgG ELISA. Selected IgM positive (n=14), IgG positive (n=23) and samples negative for both IgM and IgG (n=19) were then tested by the serum neutralization test (SNT). Sera from IgM positive (14) and negative (20) animals were also tested by a TaqMan PCR. Results from the affected farm showed that 7% (16/233) of cattle samples were IgMpositive and 13.7% (32/233) IgG positive at the first collection of samples, and 2% were IgM-positive at the second sample collection. The number of cattle positive for RVF virus-specific IgG antibodies increased by 20.3% when compared to the first bled. Only 1.4% of sheep were both positive for anti-RVF virus IgM and IgG antibodies at the first collection; IgM-positive cases decreased to 1.2%, while IgG-positive cases increased to 2.4% at the second bled. Although no IgM-positive cattle could be found on the neighbouring farm, 5.5% of cattle were IgG-positive. The SNT confirmed most of the ELISA results. Three samples that tested positive for anti-RVF virus IgM and one anti-RVF virus IgG positive sample using ELISA tested negative using the SNT. Two samples that tested negative for both IgM and IgG antibodies using ELISA, tested low positive (1:10 and 1:20) using the SNT. All samples tested using a TaqMan PCR were negative. On the affected farm, apart from the seven calves that died, cattle were also infected. There was evidence of virus circulation on the neighbouring farm but the negative PCR results indicate that at the time the animals were sampled they were not viraemic. How the virus was introduced onto the farm is not clear. The possibility of low level virus circulation in animals and the reactivation of virus from endemic foci by the breeding of vector competent mosquitoes on the low-lying area on the farm in Bela-Bela may have led to ideal circumstances for an outbreak to occur. The fact that mostly cattle seroconverted suggests a higher host preference of the local population of mosquitoes for cattle rather than sheep. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Veterinary Tropical Diseases / unrestricted

No description available.

Twenty Holsteins, ten pregnant heifers and ten pregnant cows (third or greater pregnancy) were subdivided and fed either a low calcium (Ca) or Ca-supplemented ration for four weeks prepartum to determine the influence of age and prepartum Ca intake on hormonal control of peripartum Ca homeostasis. Jugular blood samples were taken on a fixed schedule from 21 days prepartum through 21 days postpartum for parathyroid hormone (PTH), calcitonin (CT), Ca, magnesium (Mg), and phosphorus (P) analysis. Heifers and cows receiving the high Ca ration prepartum tended to have higher prepartum serum Ca. Cows fed the high Ca ration prepartum (hi-Ca cows) exhibited severe hypocalcemia (6.1 mg/dl) at parturition and remained hypocalcemic for three days. Serum PTH concentration increased prepartum (-5 to -3 days) and at parturition, followed by an increase in CT, in all groups except high-Ca cows. Circulating CT was lower in high-Ca cows throughout the experiment. Serum concentrations of PTH and Mg increased from 7 to 21 days in all except high-Ca cows. Feed intake corrected for metabolic bodyweight was similar for both dietary treatments and ages. Milk production was greater for the first week in cows fed low Ca prepartum. There was no correlation between hypocalcemia and increased milk Ca concentration. In conclusion, heifers were able to achieve calcium homeostasis despite the high Ca ration, while high-Ca cows exhibited subclinical milk fever. / M.S.

Fifteen calves of two sires were fed endophyte infected (E + ) fescue seed to quantify differences in susceptibility to fescue toxicosis among sire groups. One of the sires, a Polled Hereford, had a commercial reputation of producing calves with less severe symptoms of tall fescue toxicosis than their contemporaries. The control sire, also a Polled Hereford, had unknown merit with regard to offspring susceptibility to fescue toxicosis. The study was divided into five phases, two in which endophyte-infected fescue seed was included in the diet (phases two and four) and three in which fescue seed was not in the diet (phases one, three, and five). All calves were treated similarly and given the same opportunities for water, shade and socialization. Susceptibility to fescue toxicosis was measured by appetite (amount of feed consumed per day per unit of metabolic body weight), serum prolactin, cholesterol, and alkaline phosphatase concentrations, ability to maintain homeotherny (afternoon minus morning rectal temperature), ability to dissipate core body heat (afternoon minus morning surface temperature), and heat-transfer inefficiency (afternoon rectal minus afternoon surface temperatures). Appetite was decreased by the E + fescue seed, but the sire groups did not differ in their response to or recovery from E + fescue seed. The E + fescue seed caused prolactin to decrease (P < .0001) but the sire groups did not differ in their responses to addition or withdrawal of E + fescue seed from the diet. Cholesterol levels were lower overall (P < .001) when the E+ fescue seed was fed, and the sire groups recovered from the fescue toxicity at different rates (P < .001). Alkaline phosphatase concentrations were lower during the phases when E + fescue seed was fed; calves from the control sire were less resistant to the E + fescue seed effects than the Missouri calves (P < .0001). Ability to maintain homeothermy was reduced by the E + fescue seed, but the reduction did not differ between sire groups. Surface temperature changes and heat-transfer inefficiencies were not indicative of fescue toxicosis in this study. It was concluded that serum cholesterol and serum alkaline phosphatase concentrations may be accurate indicators of differences among paternal half sib groups of cattle in susceptibility to fescue toxicosis. / Master of Science

A dairy cow body condition scoring system was devised by the author as a practical means of determining the body condition, or fitness pertaining to the degree of body fat of dairy cows at any point during the lactation cycle. The factors considered were the thoracic and lumbar regions of the vertebral column (chine, loin and rump), spinous processes (loin), anterior coccygeal vertebrae (tailhead), tuber sacrale (hooks), and tuber ishii (pin bones). All factors in the body condition scoring system must be considered while appraising each cow. Each cow was scored on a 1 to 5 scale with 1 indicating severe undercondition and 5 indicating severe overcondition. During an 18-month period, 28 cows in each of 29 Virginia dairy herds were used for obtaining body condition scores, body weight, frame size measurements and blood samples. Herds were chosen according to rolling herd milk production average and cows were chosen at random from within five Estimated Relative Producing Ability groupings to insure a representative sample of herds across and levels of production in Virginia and of cows within each herd. Herds were sampled at 3-month intervals and complete Dairy Herd Improvement Association records were obtained for each cow in each herd. The relationships of dairy cow body weight, frame size measurements, milk production and related parameters, and blood profiles to the body condition scoring system were determined. Body condition using this method was found to be independent of frame size and only moderately correlated with body weight, the number of intercostal spaces and the ratio of body weight to wither height. Body condition was found to be relatively low during early lactation and to increase through late lactation and remain constant during the dry period. Dairy cows of greatest milk production efficiency did not increase significantly in body condition throughout lactation, had fewer days open, but had less persistency of lactation. Dairy cows that increase significantly in body condition throughout lactation were less efficient milk producers, had a greater number of days open, had relatively high body condition scores in late lactation, but had greater persistency of lactation. Blood parameters, although statistically significant in many cases, were found to be of little or no practical value when compared between body condition, stage of lactation, and dairy merit groupings. The dairy cow body condition scoring system is a practical means of quantitating body condition of dairy cows. / Ph. D.

A bidirectional selection experiment for increased and decreased somatic cell counts (SCC) in milk was conducted with two selected lines (high line or HSCC, low line or LSCC) and one control line (CSCC) of mice. Distribution of milk SCC in mice was 4 to 5 times the distribution in Holsteins. The shape of the lactation curve of mice was similar to that of Holsteins with maximum yield at day 7 (2.06 gms). The phenotypic regression of lactation milk yield on lactation milk SCC (-0.276) was significant (P < .05) and indicated that dams with higher SCC produce less milk. Small phenotypic correlations of milk SCC with blood SCC (-0.09) and percentage phagocytic cells (-0.06) were found, indicating that these traits are unrelated. A small but significant (P < .05) negative correlation (-0.14), was found between response to endotoxin challenge and milk SCC indicating that dams with inherently higher milk SCC responded less to endotoxin challenge than dams with lower milk SCC. No major pathogens which cause mastitis in cattle were detected in milk of mice. In addition, the bacteria identified (Bacillus sp., Corynebacterium sp. etc) did not cause any serious infections and/or increase in milk SCC in mice. Selection for high and low milk SCC produced a symmetrical response in the two selected lines (HSCC and LSCC), such that after 7 generations of selection, the two lines differed by more than 500,000 cells/ml of milk. A small negative genetic regression ( -0.162) of milk yield on milk SCC suggested a small correlated response in yield opposite in direction from the direct response for milk SCC. Small negative genetic regressions of blood SCC and percentage phagocytic cells on milk SCC ( -0.087 and -3.492) suggested that these three traits are genetically independent. Selection on milk SCC did not result in change either in total leukocytic cells per ml of blood or in percentage phagocytic leukocytes in blood. A negative genetic regression of response to challenge on milk SCC (-3.201) was found suggesting that selection for low milk SCC results in an increase of the ability of the individual mouse to elevate milk SCC after an injection with E. coli endotoxin. However, more data are needed to confirm this conclusion. Phenotypic correlations between milk SCC and several measures of fitness and genetic regressions of these measures on milk SCC were negligible. / Ph. D.

Die vorliegende Analyse diente dem Ziel, Krankheitsschwerpunkte bei Rindern in den Jahren 1968 bis 1999 aus der Sicht der Medizinischen Tierklinik, Leipzig, nach Häufigkeit, Rasse-, Alters-, Jahreszeit- und Geschlechtsdisposition, Behandlungsdauer sowie –erfolg aufzuzeigen. In dem genannten Zeitraum wurden 2295 Rinderpatienten gemäß der Daten in den Kliniktagebüchern unter Berücksichtigung der wechselnden gesellschaftlichen und Besitzverhältnisse ausgewertet. Im Analysezeitraum nahmen Infektionskrankheiten ab, manche, wie z.B. Leukose, Brucellose und Tuberkulose, verschwanden ganz. Auch die Puerperale Hämoglobinurie sowie die Rachitis werden nicht mehr beobachtet. Dafür stieg der Anteil Verdauungsstörungen durch die Dislocatio abomasi beträchtlich an.

Brucellosis is a disease of socio-economic and zoonotic importance worldwide. In animals it is associated with the ingestion of feed that is contaminated with cyetic material from aborting herd-mates, while in humans it is associated with the consumption of unpasteurised milk and dairy products from infected animals. It may also be acquired from contact with infected material of animal origin by farmers, veterinarians, and abattoir and laboratory workers. Brucellosis was first reported in South Africa in the late nineteenth century. It is still present in the country today, with reported annual losses of at least R 300 million, and a national annual incidence of 5 000 cases in humans. The global incidence of human brucellosis is about half a million infections annually. As the incidence of human brucellosis is directly associated with prevalence in animals, control of animal brucellosis is emphasised. Veterinary control is compromised by the chronic nature and the variable incubation period of the disease, with an estimated up to 15% of cattle in infected herds aborting before sero-conversion. Latency, which involves about 5% of calves born from infected dams, is also problematic as these infected animals often test seronegative, only to seroconvert in the peri-parturient period, thus allowing opportunity for disease spread within and between herds before diagnosis is made. In addition, the currently used serological tests are at times unable to distinguish brucellosis from cross-reacting antibodies from other infections or brucellosis vaccines. x It was the objective of this study to investigate, under South African conditions, the value of the brucellin skin test (BST) in improving the sensitivity and specificity of the currently used serological tests. It has proved a valuable additional test in diagnosing early and latent infections as well as in differentiating brucellosis from cross-reacting organisms in unvaccinated cattle in Europe. The study also evaluated the benefit of replacing some of the currently used serological assays with the fluorescence polarisation assay (FPA). The FPA, a rapid and homogenous serological test with only a few operational steps, has been validated and is in current use in Canada. The study was carried out in Mpumalanga Province, on herds selected to reflect prevailing South African farming conditions. These herds were divided into certified Brucella abortus-negative herds (608 head) for the estimation of BST specificity, and confirmed B. abortus-infected herds (845 head) for the estimation of BST sensitivity. The results obtained indicated the BST had a specificity of 99.18%, and a relative sensitivity of 42.86%. However, 65.38% of BST-positive animals were negative on serology. When the high specificity is considered, together with the experiences of other researchers who found that the skin test became positive earlier than serological tests, these animals may be assumed infected. It is concluded that the BST is a valuable addition to the panel of diagnostic tests currently used to identify infected herds and individuals in South Africa. The FPA, with a relative sensitivity of 93.65% and a specificity of 98.85%, can potentially be of use as a screening test under South African conditions. / Dissertation (MSc)--University of Pretoria, 2012. / gm2014 / Veterinary Tropical Diseases / unrestricted