Use of temperature sensitive microchip transponders to monitor body temperature and pyrexia in Thoroughbred foals

The aim of this study was to evaluate temperature data collected from Thoroughbred foals between birth and shortly after weaning. It provides a valuable survey with epidemiological conclusions providing insight into the temperature trends and pyretic occurrences of Thoroughbred foals during this age period. Temperature data were collected using telemetry from temperature sensitive microchips implanted into newborn foals. The system of inputting and storing temperature data was completely electronic and this study evaluated this system. It was found that this system was stable and allowed the evaluation of large amounts of frequently acquired data with little human intervention. The data obtained resulted in the valuable evaluation of age associated body temperature trends within the foals as well as providing an indication of the extent and epidemiology of pyrexia within the study cohort. The system of evaluating temperatures based both on the individual day value as well as on each individual foals prior series of temperatures shows that the use of these two criteria can be utilised simultaneously. The study provides basic information which future researchers using similar systems can use to objectively set criteria for pyrexia. An outbreak of equine encephalosis also occurred during the study period and this provided much needed prospective epidemiological information for such an outbreak, something which has not previously been documented. CopyrightDissertation (MSc (Veterinary Science))--University of Pretoria, 2009.Production Animal Studiesunrestricte

Modelling the factors affecting the probability for local rabies elimination by strategic control

Dog rabies has been recognized from ancient times and remains widespread across the developing world with an estimated 59,000 people dying annually from the disease. In 2011 a tri-partite alliance consisting of the OIE, the WHO and the FAO committed to globally eliminating dog-mediated human rabies by 2030. Regardless of global support, the responsibility remains with local program managers to implement successful elimination programs. It is well known that vaccination programs have a high probability of successful elimination if they achieve a population-coverage of 70%. It is often quoted that reducing population turnover (typically through sterilizations) raises the probability for local elimination by maintaining herd immunity for longer. Besides this, other factors that affect rabies elimination are rarely mentioned. This paper investigates the probability for local elimination as it relates to immunity, fecundity, dog population size, infectivity (bite rates), in-migration of immunenaïve dogs, and the initial incidence. To achieve this, an individual-based, stochastic, transmission model was manipulated to create a dataset covering combinations of factors that may affect elimination. The results thereof were analysed using a logistic regression model with elimination as the dependent variable. Our results suggest that smaller dog populations, lower infectivity and lower incidence (such as when epidemics start with single introductions) strongly increased the probability for elimination at wide ranges of vaccination levels. Lower fecundity and lower in-migration had weak effects. We discuss the importance of these findings in terms of their impact and their practical application in the design of dogmediated rabies control programs.https://journals.plos.org/plosntdspm2022Production Animal Studie

Risk-based evidence for animal health policy

No abstract available

Equine encephalosis in Thoroughbred foals on a South African stud farm

Thoroughbred foal body temperature data were collected from shortly after birth until shortly after weaning during the 2007/2008 season on a stud farm in the Western Cape Province of South Africa. Equine encephalosis (EE) caused by EE virus (EEV) serotype 4 (EEV-4) occurred in the foal group during the first autumn after their birth (March and April 2008). A descriptive study was undertaken to provide data on the EEV maternal antibody status, the association between pyrexia and EEV infection, and the incidence of infection amongst the foals prior to and during the episode. This included the frequent capturing of foal body temperature data and regular collection of serum and whole blood during pyretic episodes. Infection by EEV was determined using both virological and serological methods. A high EE incidence of at least 94% occurred amongst the foal cohort, despite the fact that 37% of foals had previously shown maternal antibody to EEV-4. Pyrexia in foals was not directly associated with EE infection and 41% of infected foals showed no detectable pyretic episode. Information obtained from this EE episode showed the high incidence of EEV infection in foals during the first autumn after their birth. Monitoring foal body temperature can alert farmers to outbreaks of infectious disease, such as EE. These results are relevant to the epidemiology of EE and facilitate greater understanding of it as a differential diagnosis of African horse sickness (AHS), given that EE and AHS have similar epidemiologic profiles.The Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, South Africa.http://www.ojvr.orgam201

Post-outbreak African horse sickness surveillance : a scenario tree evaluation in South Africa’s controlled area

An African horse sickness (AHS) outbreak occurred in March and April 2016 in the controlled area of South Africa. This extended an existing trade suspension of live equids from South Africa to the European Union. In the post‐outbreak period ongoing passive and active surveillance, the latter in the form of monthly sentinel surveillance and a stand‐alone freedom from disease survey in March 2017, took place. We describe a stochastic scenario tree analysis of these surveillance components for 24 months, starting July 2016, in three distinct geographic areas of the controlled area. Given that AHS was not detected, the probability of being free from AHS was between 98.3% and 99.8% assuming that, if it were present, it would have a prevalence of at least one infected animal in 1% of herds. This high level of freedom probability had been attained in all three areas within the first 9 months of the 2‐year period. The primary driver of surveillance outcomes was the passive surveillance component. Active surveillance components contributed minimally (<0.2%) to the final probability of freedom. Sensitivity analysis showed that the probability of infected horses showing clinical signs was an important parameter influencing the system surveillance sensitivity. The monthly probability of disease introduction needed to be increased to 20% and greater to decrease the overall probability of freedom to below 90%. Current global standards require a 2‐year post‐incursion period of AHS freedom before re‐evaluation of free zone status. Our findings show that the length of this period could be decreased if adequately sensitive surveillance is performed. In order to comply with international standards, active surveillance will remain a component of AHS surveillance in South Africa. Passive surveillance, however, can provide substantial evidence supporting AHS freedom status declarations, and further investment in this surveillance activity would be beneficial.http://wileyonlinelibrary.com/journal/tbed2021-04-08hj2020Production Animal StudiesVeterinary Tropical Disease

The 2011 outbreak of African horse sickness in the African horse sickness controlled area in South Africa

African horse sickness (AHS) is a controlled animal disease in South Africa, and as a result of the high mortality rates experienced, outbreaks in the AHS controlled area in the Western Cape Province have a significant impact on affected properties as well as on the exportation of live horses from the AHS free zone in metropolitan Cape Town. An outbreak of AHS serotype 1 occurred in the surveillance zone of the AHS controlled area of the Western Cape during the summer of 2011. The epicentre of the outbreak was the town of Mamre in the magisterial district of Malmesbury and the outbreak was confined to a defined containment zone within this area by movement control of all equids and a blanket vaccination campaign. A total of 73 cases of AHS were confirmed during this outbreak, which included four confirmed subclinical cases. The morbidity rate for the outbreak was 16% with a mortality rate of 14% and a case fatality rate of 88%. Outbreak disease surveillance relied on agent identification using polymerase chain reaction (PCR)-based assays, which is novel for an AHS outbreak in South Africa. The source of this outbreak was never confirmed although it is believed to be associated with the illegal movement of an infected animal into the Mamre area. This detailed description of the outbreak provides a sound scientific basis to assist decision making in future AHS outbreaks in the AHS controlled area of South Africa and in countries where AHS is an exotic or emerging disease.http://www.jsava.co.zaam2014ab201

Development of three triplex real-time reverse transcription PCR assays for the qualitative molecular typing of the nine serotypes of African horse sickness virus

Blood samples collected as part of routine diagnostic investigations from South African horses with clinical signs suggestive of African horse sickness (AHS) were subjected to analysis with an AHS virus (AHSV) group specific reverse transcription quantitative polymerase chain reaction (AHSV RT-qPCR) assay and virus isolation (VI) with subsequent serotyping by plaque inhibition (PI) assays using AHSV serotype-specific antisera. Blood samples that tested positive by AHSV RT-qPCR were then selected for analysis using AHSV type specific RT-qPCR (AHSV TS RT-qPCR) assays. The TS RT-qPCR assays were evaluated using both historic stocks of the South African reference strains of each of the 9 AHSV serotypes, as well as recently derived stocks of these same viruses. Of the 503 horse blood samples tested, 156 were positive by both AHSV RT-qPCR and VI assays, whereas 135 samples that were VI negative were positive by AHSV RT-qPCR assay. The virus isolates made from the various blood samples included all 9 AHSV serotypes, and there was 100% agreement between the results of conventional serotyping of individual virus isolates by PI assay and AHSV TS RT-qPCR typing results. Results of the current study confirm that the AHSV TS RT-qPCR assays for the identification of individual AHSV serotypes are applicable and practicable and therefore are potentially highly useful and appropriate for virus typing in AHS outbreak situations in endemic or sporadic incursion areas, which can be crucial in determining appropriate and timely vaccination and control strategies.Racing South Africa (Pty) Ltd, the Mary Slack and Daughters Foundation and Thoroughbred Racing Trust of South Africa.http://www.elsevier.com/locate/jviromet2016-10-31hb2016Equine Research CentreVeterinary Tropical Disease

A field investigation of an African horse sickness outbreak in the controlled area of South Africa in 2016

An outbreak of African horse sickness (AHS) caused by AHS virus type 1 occurred within the South African AHS surveillance zone during April and May 2016. The index case was detected by a private veterinarian through passive surveillance. There were 21 cases in total, which is relatively low compared to case totals during prior AHS outbreaks in the same region (and of the same AHS virus type) in 2004, 2011 and 2014. The affected proportion of horses on affected properties was 0.07 (95% CI 0.04, 0.11). Weather conditions were conducive to high midge activity immediately prior to the outbreak but midge numbers decreased rapidly with the advent of winter. The outbreak was localized, with 18 of the 21 cases occurring within 8 km of the index property and the three remaining cases on two properties within 21 km of the index property, with direction of spread consistent with wind‐borne dispersion of infected midges. Control measures included implementation of a containment zone with movement restrictions on equids. The outbreak was attributed to a reversion to virulence of a live attenuated vaccine used extensively in South Africa. Outbreaks in the AHS control zones have a major detrimental impact on the direct export of horses from South Africa, notably to the European Union.The Equine Health Fund–Wits Health Consortium (Pty) Ltd and the Equine Research Centre (University of Pretoria).http://wileyonlinelibrary.com/journal/tbed2020-03-01hj2020Equine Research CentreProduction Animal Studie

Evaluation of African horse sickness surveillance in the controlled area of South Africa

Surveillance is one of the core components of freedom from disease status declarations made by countries with regards to African horse sickness (AHS). This is especially true for South Africa which has a controlled area defined specifically for trade purposes. Three AHS surveillance activities are evaluated in this thesis: the surveillance during the 2016 Paarl AHS outbreak; the stand-alone freedom from disease survey undertaken in 2017; and a two-year surveillance sensitivity and probability of freedom analysis based on multiple surveillance components (passive surveillance, active sentinel surveillance and the 2017 survey) within three distinct zones in the AHS controlled area. Outbreak surveillance in 2016 established affected population proportions and these results were included as within and between-herd estimates for evaluation of surveillance in the post-outbreak period. The stand-alone 2017 survey established that the point in time probability of freedom ranged between 73.1% and 100% in March 2017. Scenario tree analysis showed that, at a design prevalence of 1 animal in 1% of herds, the median posterior probability of freedom from AHS in the AHS controlled area after the 24-month post-outbreak period was between 98.3% - 99.8%. The final median probability of freedom had been realised by the 9th month after the 2016 outbreak had been resolved. The inclusion of active surveillance provided minimal additional confidence in surveillance outcomes. Freedom from AHS was achieved fairly soon after the outbreak concluded in 2016 and this freedom was driven by the passive surveillance component. Surveillance challenges arise, in the South African context, as a result of high numbers of vaccinated animals within the population at risk, the seasonality of AHS and limitations of the DIVA (differentiating infected from vaccinated animals) capabilities of existing routine laboratory tests. Current global standards require a two-year post-incursion period of AHS freedom before re-evaluation of free zone status. Our findings show that the length of this period could be decreased if adequately sensitive surveillance is performed. In order to comply with international standards, active surveillance will remain a component of AHS surveillance in South Africa. Passive surveillance, however, can provide substantial evidence supporting AHS freedom status declarations, and further investment in this surveillance activity would be beneficial.Thesis (PhD)--University of Pretoria, 2018.Production Animal StudiesPhDUnrestricte

Equestrian Road Safety in the United Kingdom: Factors Associated with Collisions and Horse Fatalities

Over 60% of UK horse riders report having experienced a road-related near-miss or accident. The aim of this study was to describe horse-related road incidents (n = 4107) reported to the British Horse Society (2010&ndash;2020) and to identify factors associated with higher odds of collisions with another vehicle and horse fatalities using multivariable logistic regression modelling. Drivers passed the horse too closely in 84.2% of incidents while road rage and speeding were reported in 40.3% and 40.1% of incidents, respectively. Close passing distance alone (odds ratio [OR] 18.3, 95% confidence interval [CI] 6.5, 51.6) or in combination with speeding (OR 4.4, CI 1.7, 11.7) was associated with higher collision odds compared to speeding alone. Speeding was, however, associated with higher horse fatality odds (OR 2.3, CI 1.2, 4.6). Wearing high visibility clothing reduced odds of collision (OR 0.2, CI 0.1, 0.4). A fatal injury to a horse was almost 12 times as likely to result in severe to fatal rider/handler injury. Loose horses contribute significantly to road-related horse fatalities. Driver behaviour of how to pass horses safely on UK roads needs further improvement and will help reduce the risk of collisions and horse and human fatalities