1,721,012 research outputs found
Bovine cysticercosis epidemiology and the economic impact of the triceps brachii incision in a South African export abattoir
Full text linkTaenia saginata is a zoonotic tapeworm of humans with bovines as its intermediate host (bovine cysticercosis). Traditional meat inspection is the main measure to identify the larval stage in carcasses and prevent human infection, but has a notoriously low sensitivity, especially in low prevalence settings. The legislation in multiple African countries mandates an incision in both triceps brachii muscles to detect the parasite as part of the normal post-mortem inspection, but this has an economic cost and is not universally mandated in other countries. The primary aim of this study was to investigate the epidemiology of bovine cysticercosis at an export abattoir in South Africa and determine the validity and cost of the triceps incision. Risk factors were investigated, and the effect of additional heart incisions on the current inspection. Four incisions were made into the heart in addition to the normal post-mortem inspection in 3353 carcasses. The proportion of positive animals with and without the cardiac and triceps incisions were compared using McNemar's chi-square tests, while risk factors were assessed using binary logistic regression. The economic impact of the triceps incision was estimated using a stochastic economic cost model. Thirty-three positive carcasses were identified for an apparent prevalence of 0.98 % (95 %CI, 0.69-1.36 %), while the true prevalence was estimated at 6.6 % (95 %CI, 4.3-8.8 %). All cysts were confirmed as T. saginata on histopathology with 70 % (95 %CI, 53-83 %) located in the heart. The additional cardiac incisions resulted in the detection of significantly more cases compared to the normal inspection method prevalence of 0.72 % (95 %CI, 0.47-1.05 %; P < 0.001). The apparent prevalence of T. saginata when omitting the triceps incision was not significantly lower compared to the prevalence when included in the inspection (P = 0.480). External feedlots (OR= 4.17, 95 %CI: 2.04-8.54, P < 0.001) and older animals (OR=3.90, 95 %CI: 1.17-13.03, P = 0.027) were associated with a positive detection. The current median annual financial cost to the food business operator from the triceps incision was estimated at 0-$130696), with the proportion of deboned meat exported identified as the most important factor affecting cost (Spearman's rho=0.853). The identification of risk factors could aid in the development of a more effective risk-based inspection system. The current inspection should be modified to increase exposure of the heart and remove the triceps incisions. The latter should especially be considered given the minimal contribution to cysticercosis detection, the unsupported requirement for its inclusion specifically in Africa, and its economic impact, especially as beef exports increase.</p
Influence of high-protein and high-carbohydrate diets on serum lipid and fructosamine concentrations in healthy cats
Full text linkObjectives: The aim of this study was to determine whether high-protein and high-carbohydrate diets exert differential effects on serum cholesterol, triglyceride and fructosamine concentrations in healthy cats. Methods A randomised, crossover diet trial was performed in 35 healthy shelter cats. Following baseline health assessments, cats were randomised into groups receiving either a high-protein or high-carbohydrate diet for 4 weeks. The cats were then fed a washout diet for 4 weeks before being transitioned to whichever of the two studied diets they had not yet received. Fasting serum cholesterol, triglyceride and fructosamine concentrations were determined at the end of each 4-week diet period. Results Cats on the high-carbohydrate diet had significantly lower serum cholesterol ( P 5) had lower cholesterol ( P = 0.007) and triglyceride ( P = 0.032) concentrations on the high-protein diet than cats within other BCS groups. Conclusions and relevance Diets higher in protein and lower in carbohydrates appear beneficial for short-term glucose control in healthy cats. A high-protein diet was associated with significantly elevated cholesterol and triglyceride concentrations in healthy cats, even though the increase was significantly less pronounced in cats with a BCS >5. This finding suggests that overweight cats process high-protein diets, cholesterol and triglycerides differently than leaner cats
Small colon impaction outbreak and associated risk factors in horses at the Onderstepoort Veterinary Academic Hospital, South Africa in 2021
Full text linkDissertation (MMedVet (Equine Surgery))--University of Pretoria, 2024.Background
During June-July 2021, the Onderstepoort Equine Clinic experienced an increase in diffuse faecal small colon impactions (SCI). Typically, SCI is diagnosed in 1.3–3% of horses admitted to referral centres for colic.
Objectives
This study aimed to describe the distribution, diagnosis, treatment, and outcomes of colic cases in 2021, focusing on SCI and to identify risk factors for SCI compared to large colon impactions (LCI).
Method
Medical records from the Onderstepoort Veterinary Teaching Hospital were reviewed to identify colic cases in 2021 and the population distribution, diagnosis, treatment, and outcome recorded. Cases of SCI were identified and compared to LCI. Owner questionnaires assessed potential SCI risk factors.
Results
Colic cases(182), comprised mainly LCI(26%), large colon displacements(20%), and SCI(13%). Treatments included medical(65%), surgical(32%), or euthanasia(3%). Most horses(85%) were discharged. SCI was diagnosed in 13% of cases, higher than previously reported rates. Immediate surgical treatment was performed in 30% of cases. In the remaining cases medical management was initiated although surgical intervention was later pursued in 43% of cases. Short-term survival was 87%, with surgical cases showing higher survival (94%) than medical (67%).
Stallions were at risk to develop SCI compared to “all colic” diagnoses (OR 4.17). Friesians were more likely to develop SCI compared to “all colic” (OR 7.00). Draft breed horses were more likely to develop SCI compared to compared to “all colic” (OR 8.20) and compared to LCI (OR 32.7). The study identified a risk for horses to develop SCI in winter compared to “all colic” (OR 43.2) and compared to LCI (OR 124). Conclusion
A SCI outbreak occurred in 2021, with increased risks in stallions, Friesians, and draft breeds, particularly in winter. Horse owners and veterinarians should be alerted to this, especially in at-risk groups during winter. Outcomes are favourable for SCI especially when treated surgically.Companion Animal Clinical StudiesMMedVet (Equine Surgery)UnrestrictedFaculty of Veterinary Scienc
Evaluation of the solid-phase competition ELISA for detecting SAT foot-and-mouth disease virus vaccination and infection in goats
Full text linkDissertation (MSc (Tropical Animal Health))--University of Pretoria, 2021.Foot-and-mouth disease (FMD) is a highly contagious and widely distributed disease affecting cloven-hoofed animals. The exact role played by goats in the epidemiology of the Southern African Territories (SAT) serotypes is an area currently under investigation. In this study, diagnostic properties of the solid phase competition ELISA (SPCE) were estimated using serum samples collected from goats that had participated in a FMD vaccination and challenge study. The goats were vaccinated with a pentavalent vaccine containing two SAT1 viruses, two SAT2 viruses and one SAT3 virus. After vaccination, the goats were challenged with a pool of three field SAT1 viruses. The SPCE were performed initially using a single-spot version (SS-SPCE) that was followed by a half-titration SPCE (T-SPCE) performed specifically for this study. The two independent runs (SS-SPCE and T-SPCE) were conducted in duplicate on two separate occasions. The repeatability of the assay was estimated from the duplicate wells (intra-aassay) and also from mean percentage inhibition from the separate tests (inter-assay). The coefficients of variations calculated from the duplicate percentage inhibitions from each of the two test runs were used to calculate within run repeatability while the mean percentage inhibitions for each run were used to measure inter-assay repeatability. The mean percentage inhibitions from the independent SPCE runs were used to estimate the level of correlation, agreement and relationship between them. The mean percentage inhibitions from each of the two SPCE runs were also compared to titer and the correlation, agreement and relationships were estimated. The ROC curve and area under the curve were used to estimate the accuracy of the SPCE and the optimum threshold cut off of the SPCE method across all three SAT serotypes was determined based on the Youden index (Y = maxc (Se (c) + Sp (c) – 1)). Approximately 80% of all intra-assay and 60% of all inter-assay SPCE results across all SAT serotypes had a good repeatability (<20% coefficient of variation). There was a very strong correlation between the two SPCE test runs and the titer results (Spearman’s rho=0.8 to 0.97). The agreement between the both SPCE runs was substantial across all serotypes, with kappa values ranging from 0.74 to 0.82. However, when the individual SPCE runs were compared with titer, the agreement was not as strong and differed according to serotype. SAT 1 agreement was moderate to substantial (k=0.592 and 0.612), SAT2 was moderate (k=0.423) and SAT3 was fair (k=0.24 and 0.309). The area under the T-SPCE ROC curve for SAT1, SAT2 and SAT3 was 0.98, 0.979 and 0.953 respectively, indicating a high diagnostic accuracy. The optimum SPCE percentage inhibition cut off based on the Youden index was found to be 75.63% PI for SAT1, 76.6% PI for SAT2 and 71.6% PI for SAT3. The cut off determined by this study were significantly higher when compared to the one normally used for this assay.Veterinary Tropical DiseasesMSc (Tropical Animal Health)Unrestricte
Clinical and epidemiological investigations of Orbivirus infections in domestic dogs (Canis lupus familiaris)
No full textThesis (PhD (Veterinary Science))--University of Pretoria, 2023.Dogs are atypical host species for some of the most economically important orbiviral diseases, African horse sickness (AHS) and bluetongue (BT). Dogs are the only non-equid species to develop the severe fatal form of AHS, and along with the Eurasian lynx, dogs are the only non-ruminants to develop fatal bluetongue (BT). However, the role of dogs as a host species for orbiviruses has been largely dismissed as incidental or of low significance in the epidemiology of orbiviruses. In light of recent dog mortalities due to AHS which occurred with suspected midge-borne transmission, this thesis examines clinical and epidemiological features of Orbivirus diseases in South African dogs. The author shows that exposure to the African horse sickness virus (AHSV) in dogs in Tshwane, South Africa was common and frequent, with as many dogs estimated to have been exposed to AHSV as the population of horses in the area. At the onset of this investigation, only AHS had been described in South African dogs. The author describes the novel identification of the bluetongue virus (BTV) and possible equine encephalosis virus in South African dogs. The author describes the clinical presentation and management of a pregnant dog diagnosed with naturally occurring BT. The author investigates the farm of origin for this dog and shows a high level of exposure to BTV in dogs on the farm was high and detected the viral RNA from blood samples in three dogs (50%). The author reports the detection of equine encephalosis from samples collected from a puppy with a fatal respiratory disease. The findings of this study suggest dogs could play a greater role in the persistence, spread and introduction of orbiviruses than previously thought.Companion Animal Clinical StudiesPhD (Veterinary Science)UnrestrictedFaculty of Veterinary ScienceSDG-02: Zero HungerSDG-03: Good health and well-beingSDG-15: Life on lan
Accuracy of end-on fluoroscopy in predicting implant position in relation to the vertebral canal in dogs.
Full text linkObjective
To evaluate the accuracy of end-on fluoroscopy in predicting implant position in relation to the vertebral canal in the canine thoracolumbar vertebral column.
Study design
In vitro imaging and anatomic study.
Animals
Canine cadaveric thoracolumbar vertebral columns (n = 5).
Methods
Smooth Steinmann pins were inserted bicortically into the thoracolumbar vertebral columns between T10 and L7 using recommended insertion angles. Penetration of the spinal canal was not strictly avoided. After pin placement, end-on fluoroscopy images were obtained of each pin. Pin position was subsequently assessed by four evaluators and determined to either being out of the vertebral canal or in, with the latter being additionally divided into partially or completely penetrating the canal. To assess potential differences in modalities, fluoroscopy images were gray-scale inverted and evaluated again later by the same four individuals. Correct identification of pin position in relationship to the vertebral canal was assessed for both fluoroscopy images. Anatomic preparation of the spines was used for verification of pin position in relation to the spinal canal. Some data from this study were compared with historical data on accuracy using orthogonal radiography and computed tomography (CT).
Results
Overall sensitivity and specificity of F to detect vertebral canal penetration was 98.8 % (95% confidence interval (CI), 96.0-99.6) and 98.0% (95% CI, 77.0-99.9), respectively. For Fi, sensitivity and specificity were 97.0% (95% CI, 91.5-99.0) and 98.5% (95% CI, 81.5-99.9) respectively. F exceeded Fi for the sensitivity of detecting pin penetration into the vertebral canal (p = 0.039) but specificities were not different (p = 0.585). When comparing to historical data, the overall accuracy of end-on fluoroscopy (F) and inverted fluoroscopy (Fi) was statistical better than conventional radiographic assessment (p < 0.001).
Conclusion
End-on fluoroscopy is a highly accurate method for the assessment of pin position in relationship to the thoracolumbar spinal canal in cadaveric dogs.
Clinical significance
End-on fluoroscopy, with or without inversion, is accurate in identifying vertebral canal violation by bicortically placed Steinmann pins. When CT is not available, end-on fluoroscopy might be a valuable imaging modality to determine pin position in the canine vertebral column
Evaluation of dietary factors associated with spontaneous pancreatitis in dogs
Full text linkThis study estimates the association between dietary factors and spontaneous pancreatitis in dogs. A case-control study was conducted using 198 dogs with a clinical diagnosis of pancreatitis and 187 control dogs with a diagnosis of renal failure without clinical evidence of pancreatitis. Information on signalment, weight, body condition, dietary intake, medical history, diagnostic tests performed, concurrent diseases, treatment, length of hospital stay, and discharge status was extracted from medical records for dogs admitted to the Texas A&M University Small Animal Clinic (TAMU SAC) during January 2000 to December 2005. Information on dietary intake, signalment, weight, medical, surgical and environmental history was collected for the same dogs through a telephone questionnaire conducted from November 2006 through January 2007. Descriptive statistics were calculated, tabular analyses performed, and logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). Based on information extracted from the medical records, ingesting unusual food (OR=4.3; CI=1.7 to 10.7), ingesting table food (OR=1.5; CI=1.0 to 2.2), or exposure to both of these dietary factors (OR=2.1; CI=1.3 to 3.2) increased the odds of pancreatitis. Collected through the telephone questionnaire, ingesting unusual food (OR=6.1; CI=2.2 to 16.5), ingesting table scraps the week before diagnosis (OR=2.2; CI=1.2 to 3.8) or regularly throughout life (OR=2.2; CI=1.2 to 4.0), and getting into the trash (OR=13.2; CI=2.1 to undefined) increased the odds of pancreatitis. Multivariable modeling estimated the associations of exposure to one or more dietary factors reported through the telephone questionnaire (OR=2.6; CI=1.4 to 5.0), overweight (OR=1.3; CI=0.7 to 2.5), year of diagnosis (OR=3.5; CI=1.9 to 6.5), neuter status (OR=3.6; CI=1.4 to 9.5), non-neuter surgery (OR=21.1; CI=3.3 to 133.9) and an interaction term between neuter status and non-neuter surgery (OR=0.1; CI=0.01 to 0.4). Dietary factors increase the odds of spontaneous pancreatitis in dogs
Three surveillance systems for describing the spatial distribution of Johne's disease seropositivity in Texas cattle
Full text linkJohne���s disease is a chronic and debilitating disease of cattle caused by infection
with Mycobacterium avium subsp. paratuberculosis (Mptb). This disease affects both
dairy and beef cattle, though it is more commonly recognized in dairy cattle. Mptb is
able to persist in the environment of cattle for extended periods of time; therefore the
distribution of the disease depends on the presence of infected animals and
environmental conditions. Three surveillance systems were used to describe the spatial
distribution of Johne���s disease seropositivity in Texas cattle. These three systems were
hypothesized to describe different spatial patterns. These systems involved sampling, 1)
herds throughout Texas, 2) market cattle from four markets each month (one each from
northern, southern, eastern, and western regions of Texas) and 3) sick animals submitted
by veterinarians throughout Texas. Samples were tested for Johne���s disease at the Texas
Veterinary Medical Diagnostic Laboratory using serum ELISA. Spatial distributions
were estimated by kriging the sample-to-positive control ratios (S/P). Sera were
evaluated for Mptb antibodies from 2358 cattle with 1084 animals in system 1, 1200
from system 2 and 74 from system 3. Total number of positive ELISA results was 51,
with 25, 19 and 7 positve ELISA results for systems one, two and three, respectively. Results showed an overall prevalence of 2.16%, and prevalence���s of 2.31%, 1.58% and
9.46% for systems one, two and three, respectively. Differences in the spatial
distribution of Johne���s disease seropositvity, based on the three surveillance systems,
confirmed our hypothesis that estimation of disease distribution is dependant upon the
source of surveillance samples
Modelling the risks of foot-and-mouth disease outbreaks and assessing the effectiveness of vaccination in South Africa
Full text linkThesis (PhD (Veterinary Epidemiology))--University of Pretoria, 2020.Transboundary animal diseases such as foot-and-mouth disease (FMD) have negative socio-economic consequences that include impacts on food security. Vaccination reduces the number of susceptible animals and is one of the most important approaches for FMD control. In South Africa, FMD outbreaks in communal areas cause major livestock and human livelihood concerns; they raise apprehensions about the effectiveness of FMD control measures within the FMD protection areas. This study aimed to inform South Africa’s FMD control policy by identifying the spatial and temporal distributions of FMD outbreaks, modelling the risks of FMDV outbreaks and assessing the effectiveness of vaccination in South Africa.
The first study used Cuzick-Edwards tests and Kulldorff scan statistics to detect spatial autocorrelation and spatial-temporal clusters of FMD outbreaks (2005 - 2016). The second study developed a new vaccine matching technique and assessed the vaccine-match of 41 FMD field viruses isolated from southern Africa (1991 - 2015). The third study developed a risk model integrating available risk factor information to identify high-risk areas for FMD outbreak occurrence and subsequent spread.
Four high-risk clusters for FMD outbreaks were identified, and the spatial distribution was consistent with contact between domestic animals and wildlife as the main contributor to FMD occurrence. Cattle numbers, cattle movement, location (province), vaccination status and vaccine matching were also important for FMD outbreak occurrences and spread. However, cattle weekly inspections were strongly related to FMD occurrence, which implies effective surveillance and inspection increased the likelihood of FMD detection. The new vaccine matching method provided a feasible and reliable approach that will contribute to the control of FMD in southern Africa.
Continued research is necessary to maximize the cost-effectiveness of FMD control in southern Africa.South African National Research Foundation (Grant Numbers 90578 and 76734) & University of PretoriaProduction Animal StudiesPhD (Veterinary Epidemiology)Unrestricte
Sensitivity and specificity of rRT-PCR, histopathology, and immunohistochemistry for the detection of rift valley fever virus in naturally-infected cattle and sheep
Full text linkDissertation (MSc)--University of Pretoria, 2014.Rift Valley fever (RVF) is a mosquito-borne zoonotic disease caused by a virus of the family
Bunyaviridae, genus Phlebovirus. It is responsible for extensive outbreaks of disease in
livestock in Africa with significant mortality and economic impact. Virus neutralization is
considered the gold standard for confirming Rift Valley fever virus (RVFV) infection but the
procedure is time consuming and expensive. Real-time reverse transcription-polymerase
chain reaction (rRT-PCR), histopathology, and immunohistochemistry (IHC) are the
diagnostic methods most often used in South Africa to confirm or exclude a diagnosis of
RVF in necropsied animals. Validated estimates of diagnostic accuracy of these tests, in
naturally infected livestock, however, have not been published. The objective of this study was to estimate the diagnostic sensitivity and specificity of rRT-PCR, histopathology, and
IHC using Bayesian latent class methods in the absence of a gold standard. A secondary
objective was to estimate stratum-specific values based on species, age, degree of
specimen autolysis, and the presence/absence of tissue pigments.
The Sensitivity (Se) and Specificity (Sp) of qRT-PCR were 97.4% (95% credibility interval
(CI): 95.2% - 98.8%) and 71.7% (95% CI: 65% - 77.9%) respectively. The extraordinary
analytical sensitivity of PCR makes this test very susceptible to false positive reactions, and
thus reduced specificity. This is more likely during large-scale epidemics due to crosscontamination
of specimens at necropsy facilities or testing laboratories.
The Se and Sp of histopathology were 94.6% (95% CI: 91% - 97.2%) and 92.3% (95% CI:
87.6% - 95.8%) respectively. Single cases of RVF could be confused with acute poisoning
with plants, bacterial septicaemias, and viral diseases such as infectious bovine
rhinotracheitis and Wesselsbron disease. Most of these conditions, however, can be
excluded using histological examination of the liver, special stains, bacterial culture, and
toxicological or serological investigations. The Se and Sp of IHC were 97.6% (95% CI: 93.9% - 99.8%) and 99.4% (95% CI: 96.9% -
100%) respectively. Immunohistochemistry is highly specific because characteristic positive
immunolabelling of the cytoplasm of hepatocytes can be correlated with the presence of
hepatocellular injury typical for RVFV infection. False negative results are sometimes
obtained with IHC because of reader error or loss of the antigenic epitopes due to advanced
autolysis. Scant positive immunolabelling might be missed or viral proteins might be absent
from sections of liver with advanced hepatocellular damage.
The stratified analysis suggested differences in test accuracy in foetuses and severely
autolysed specimens. The Sp of histopathology in foetuses (83.0%) was 9.3% lower than
the value obtained for the sample population (92.3%). Lesions in some foetuses are more
subtle and the typical eosinophilic intranuclear inclusions are often difficult to detect. In
severely autolysed specimens, the Se of IHC decreased by 16.1% and the Sp of rRT-PCR by 17.4%. There is no plausible biological explanation for this decrease in the Sp of rRTPCR
since the RNA of RVFV is resistant to degradation in autolysed tissues. Conversely,
the antibody used to detect RVFV using IHC detects epitopes raised against nucleoproteins
of the virus and it is possible that viral proteins become too widely dispersed and/or
degraded in autolysed tissues to detect by light microscopy. It is possible that the marked
decrease in Se of histopathology and IHC in severely autolysed specimens caused an
apparent decrease in Sp of rRT-PCR, due to the latent class method.
In conclusion, the high estimated Sp (99.4%) of IHC and the low Sp of rRT-PCR (71.3%)
suggests that the definitive diagnosis or exclusion of RVF should not rely on a single PCR
test and that IHC would be an effective confirmatory test for rRT-PCR positive field cases
necropsied during an epidemic. Immunohistochemistry results from severely autolysed
specimens, however, should be interpreted with caution and aborted foetuses in areas
endemic for RVF should be screened using a variety of tests. The diagnostic Se and Sp of
histopathology was much higher than expected confirming the value of routine post mortem
examinations and histopathology of liver specimens. The most feasible RVF testing option
in areas that do not have suitably equipped PCR laboratories, and where disease is often
not detected in livestock until after human cases have been diagnosed, would be routine
histopathology screening with IHC confirmation.
Key Words: Rift Valley fever; Rift Valley fever virus; Bayesian; latent-class model; real-time
reverse transcription-polymerase chain reaction; immunohistochemistry; histopathology;
diagnosis; sensitivity; specificity.gm2014Paraclinical Sciencesunrestricte
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