John Duncan Grewar

South African Equine Health and Protocols · Research and Innovation

In North America, range constraints due to burgeoning development increasingly encroach on wild horse habitat and necessitate effective but humane reproductive management. The largest free-roaming wild horse fertility control program by population (>3500) and territory size (≈300,000 acres) is located within Nevada’s Virginia Range. Data from a fie...

African horse sickness is an equine orbivirus transmitted by Culicoides Latreille biting midges. In the last 80 years, it has caused several devastating outbreaks in the equine population in Europe, the Far and Middle East, North Africa, South-East Asia, and sub-Saharan Africa. The disease is endemic in South Africa; however, a unique control area...

In southern Africa, clade 2.3.4.4B H5N1 high pathogenicity avian influenza (HPAI) was first detected in South African (SA) poultry in April 2021, followed by outbreaks in poultry or wild birds in Lesotho and Botswana. In this study, the complete or partial genomes of 117 viruses from the SA outbreaks in 2021–2022 were analyzed to decipher the sub-r...

African horse sickness (AHS) is one of the economically most important equid diseases in southern Africa, contributing significantly to equine morbidity and mortality. Annual vaccination with the Onderstepoort Biological Products polyvalent live attenuated vaccine has been the mainstay of prevention in South Africa. The study objectives were to det...

Introduction: Police-recorded road injury data are frequently used to approximate injury risk for different road user groups but a detailed analysis of incidents involving ridden horses has not previously been conducted. This study aims to describe human injuries resulting from interactions between ridden horses and other road users on public road...

Background During 2019, an epidemic of equine influenza (EI) occurred in Europe. Objectives To describe the epidemiology of the 2019 EI epidemic within Great Britain (GB). Study design Retrospective descriptive study of laboratory confirmed EI cases. Methods Epidemiological data were obtained from veterinary surgeons referring samples for EI vir...

We identified and isolated a novel Hendra virus (HeV) variant not detected by routine testing from a horse in Queensland, Australia, that died from acute illness with signs consistent with HeV infection. Using whole-genome sequencing and phylogenetic analysis, we determined the variant had ≈83% nt identity with prototypic HeV. In silico and in vitr...

Introduction While modern vehicles have become faster, quieter and safer for the occupants, the innate behaviour and physical capability of horses has not changed. There has been a considerable shift in the way that horses are used on roads but also how they are perceived by other road users [1]. Interactions between horses, their human handlers an...

Infection dynamics data for influenza A virus in a species is important for understanding host-pathogen interactions and developing effective control strategies. Seven-week-old ostriches challenged with H7N1 low pathogenic viruses (LPAIV) or clade 2.3.4.4B H5N8 high pathogenic viruses (HPAIV) were co- housed with non-challenged contacts. Clinical s...

Background: Previously national surveillance data for monitoring strangles (Streptococcus equi infection) in UK horses was limited. Improved awareness and knowledge of positive diagnoses would permit the optimisation of biosecurity protocols, decreasing the prevalence of strangles. Methods: Seven UK laboratories reported positive strangles diagnos...

A novel Hendra virus (HeV) variant, not detected by routine testing, was identified and isolated from a Queensland horse that suffered acute, fatal disease consistent with HeV infection. Whole genome sequencing and phylogenetic analysis demonstrated the variant to have ~83% nucleotide identity to the prototype HeV strain. An updated RT-qPCR assay w...

South Africa is endemic for African horse sickness (AHS), an important health and trade-sensitive disease of equids. The country is zoned with movement control measures facilitating an AHS-free controlled area in the south-west. Our objective was to quantitatively establish the risk of entry of AHS virus into the AHS controlled area through the leg...

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 respons...

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 (2010–2020) and to identify factors associated with higher odds of collisions with another vehicle and horse fatalities using multivariable lo...

n the Cape Flats townships, Cape Town, South Africa, there are more than 250 working cart horses. They serve the community with scrap metal and garden refuse removal, human transport and the selling of goods. A questionnaire was undertaken to understand the social and economic impacts of a horse and cart in the Cape Flats on individual owners and/o...

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‐...

With the current trend in animal health surveillance toward risk-based designs and a gradual transition to output-based standards, greater flexibility in surveillance design is both required and allowed. However, the increase in flexibility requires more transparency regarding surveillance, its activities, design and implementation. Such transparen...

With the current trend in animal health surveillance toward risk-based designs and a gradual transition to output-based standards, greater flexibility in surveillance design is both required and allowed. However, the increase in flexibility requires more transparency regarding surveillance, its activities, design and implementation. Such transparen...

With the current trend in animal health surveillance toward risk-based designs and a gradual transition to output-based standards, greater flexibility in surveillance design is both required and allowed. However, the increase in flexibility requires more transparency regarding surveillance, its activities, design and implementation. Such transparen...

African horse sickness (AHS) is a disease of equids that results in a non-tariff barrier to the trade of live equids from affected countries. AHS is endemic in South Africa except for a controlled area in the Western Cape Province (WCP) where sporadic outbreaks have occurred in the past 2 decades. There is potential that the presence of zebra popul...

African horse sickness (AHS) is a disease of equids that results in a non-tariff barrier to the trade of live equids from affected countries. AHS is endemic in South Africa except for a controlled area in the Western Cape Province (WCP) where sporadic outbreaks have occurred in the past 2 decades. There is potential that the presence of zebra popul...

An African horse sickness (AHS) outbreak occurred in South Africa's AHS controlled area in autumn 2016. A freedom from disease survey was performed to establish the likelihood of ongoing circulation of the associated virus during the same period the following year. A single-stage surveillance strategy was employed with a population-level design pre...

Objective(s): In the Cape Flats townships, Cape Town, South Africa, there are in excess of 250 working horses, known as ‘cart horses’ in the community. They serve the community with scrap metal collection and transportation, garden refuse removal, human transport and the general selling of goods. A study was undertaken to understand the social and...

Objective(s): An analysis of all live equids traded during 2015 and 2016 was performed to establish the trade patterns of these animals in where their destination was one of the SADC (Southern African Development Community) countries to establish a risk profile for Southern Africa and trade within the region. Materials and methods: UNCOMTRADE is a...

Objective(s): Outbreaks of disease, such as the highly pathogenic (HPAI H5N8) outbreak that occurred in South Africa in 2017/2018, result in significant stress to both the industries affected and the control authorities. This becomes exacerbated when outbreaks are spread over a large area with different reporting and control structures, resulting i...

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...

This case report shows that Mycobacterium avium subsp. paratuberculosis (MAP) infection can cause clinical disease in domestic dogs, and should be considered as a differential diagnosis for gastrointestinal inflammatory conditions. A male dachshund presented with lethargy and pain. Enlarged mesenteric lymph nodes were found on abdominal ultrasound...

African horse sickness (AHS) is a fatal disease of equids relevant to the global equine industry. Detection of AHS virus (AHSV) during outbreaks has become more rapid and efficient with the advent of group specific reverse transcriptase quantitative polymerase chain reaction (GS RT-qPCR) assays to detect AHSV nucleic acid. Use of GS RT-qPCR togethe...

African horse sickness (AHS) is a hemorrhagic viral fever of horses. It is the only equine disease for which the World Organization for Animal Health has introduced specific guidelines for member countries seeking official recognition of disease-free status. Since 1997, South Africa has maintained an AHS controlled area; however, sporadic outbreaks...

Metadata for each of the 39 African horse sickness (AHS) virus type 1 field isolates from the Stellenbosch, Mamre, Porterville, and Robertson AHS outbreaks in the AHS controlled area in Western Cape Province, South Africa, 2004–2014.

Additional details about relationships between African horse sickness viruses related to outbreaks in South Africa and reference viruses.

Bluetongue (BT) and African horse sickness (AHS) are considered the most important orbiviral diseases in Southern Africans countries. The general endemic status makes these diseases challenging to be quantified in terms of their economic impact. Using country reported data from BT and AHS outbreaks and cases, as well as international trade data, th...

In 2011, the commercial ostrich production industry of South Africa experienced an outbreak of highly pathogenic avian influenza (HPAI), subtype H5N2. Surveillance using antibody and antigen detection revealed 42 infected farms with a between-farm prevalence in the affected area of 16%. The outbreak was controlled using depopulation of infected far...

African horse sickness (AHS) is a severe, often fatal, arbovirus infection of horses, transmitted by Culicoides spp. midges. AHS occurs in most of sub-Saharan Africa and is a significant impediment to export of live horses from infected countries, such as South Africa. A stochastic risk model was developed to estimate the probability of exporting a...

Simulation results for base scenarios. (ZIP)

Simulation results for sensitivity analysis on breakdown of vector protection during quarantine. (ZIP)

Results of sensitivity analysis on the probability of breakdown of vector protection during pre-export quarantine. A, Low-risk area, Breakdown = gamma(24, 2191); B, Low-risk area, Breakdown = gamma(1, 5000); C, Low-risk area, Breakdown = gamma(1, 500); D, Low-risk area, Breakdown = gamma(1, 50); E, Low-risk area, Breakdown = gamma(1, 10); F, Low-ri...

Map of AHS Controlled Area of South Africa. (PDF)

Results of sensitivity analysis on the probability of breakdown of vector protection during loading. A, Low-risk area, LoadingBreakdown = gamma(1, 500); B, Low-risk area, LoadingBreakdown = gamma(1, 50); C, Low-risk area, LoadingBreakdown = gamma(1, 10); D, Low-risk area, LoadingBreakdown = gamma(1, 5); E, Endemic area, LoadingBreakdown = gamma(1,...

Simulation results for comparison of high and low PCR sensitivity. (ZIP)

Simulation results for sensitivity analysis on breakdown of vector protection during loading. (ZIP)

ABSTRACT. It is extremely important for biodiversity conservation that protected areas are resilient to a range of potential future perturbations. One of the least studied influences on protected area resilience is that of disease. We argue that wildlife disease (1) is a social-ecological problem that must be approached from an interdisciplinary pe...

A discussion on selecting appropriate graphs for the depiction of scientific results based on the work by Dave Kelly, Jaap Jasperse and Ian Westbrooke i.e. "Designing science graphs for data analysis and presentation." Department of Conservation Technical Series 32 (2005)

Hexagons are common in nature, and even the humble honey bee has realised that if you want to store something properly then a hexagon is the way to go. It is common practice in mapping to display collated data on a square grid background. One of the major reasons for this is that square grids form the intrinsic backdrop to most imagery, given that...

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 se...

The resilience literature often assumes that social–ecological reorganization will result in either the removal of deficient system elements (components, interactions) or social learning. Major perturbations are expected to lead to either adaptation or, if accompanied by a regime shift, transformation. This has led to a conflation of the concepts o...

Context Landscape structure influences host–parasite– pathogen dynamics at multiple scales in space and time. Landscape epidemiology, which connects disease ecology and landscape ecology, is still an emerging field. Objective We argue that landscape epidemiology must move beyond simply studying the influence of landscape configuration and compositi...

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 Apri...

The focus of management in many complex systems is shifting towards facilitation, adaptation, building resilience, and reducing vulnerability. Resilience management requires the development and application of general heuristics and methods for tracking changes in both resilience and vulnerability. We explored the emergence of vulnerability in the S...

Other avian influenza viruses were detected during the course of routine and outbreak response surveillance within the Western Cape Province of South Africa during the course of the highly pathogenic H5N2 avian influenza (HPAI) outbreak the Western Cape experienced during 2011. Included in these events have been outbreaks of low pathogenic H5N2 avi...

The third outbreak of highly pathogenic avian influenza (HPAI) H5N2 in less than seven years affected ostriches of South Africa's Western Cape during 2011. Twenty farms tested PCR positive for the presence of HPAI H5N2 between March and November 2011. Three HPAI H5N2 (AI2114, AI2214, AI2512) and 1 H1N2 (AI2887) viruses were isolated during this per...

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 out...

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