Research Articles (Production Animal Studies)

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Efficacy, safety and interval from end of treatment to estrus in cats treated with an ultra-low dose megestrol acetate protocol for suppression of reproductive activity
(Elsevier, 2025-10) Pereira, Maria; Grassi, Anna; Pipan, Maja Zakosek; Contato, Giulia; Dal Ponte, Giada; Ghezzo, Anna; De Cramer, Kurt Guido Mireille; Romagnoli, Stefano
Cat breeders need safe, predictable and fully reversible temporary control of reproduction in queens. Megestrol acetate (MA), a short-acting progestogen was investigated in this study designed to determine whether low-dose treatment is both effective and safe in cats for periods up to 6 months. Twenty-eight queens were treated orally with 11.5 μg/kg/day of MA for one to six months. A physical examination, vaginal cytology, and reproductive ultrasound were performed before, during and after treatment, whilst urinalysis and hematological/biochemical tests, including progesterone assay, were performed before and after treatment. MA suppressed reproductive function effectively in 27/28 queens. Transient mammary and uterine hyperplasia were detected in four (14 %) and three (11 %) queens, respectively, treated for more than four months, without associated clinical signs. Pyometra was observed in only one queen following her first estrus cycle post-treatment. Significant but reversible weight gain was observed in 85 % of the animals. The resumption of cyclicity occurred on average 6 weeks after the end of treatment but was influenced by the duration of treatment and seasonality. An ultra-low dose MA treatment was effective in suppressing estrus in queens treated up to 6 months. Close monitoring should be paid to queens treated for longer than 4 months as the incidence of side effects, albeit minor and manageable, increases thereafter. Mammary gland assessment and progesterone assay are indispensable before treatment. Fertility is preserved, making MA a valuable option for temporary control of reproductive activity in queens, who otherwise cycle continuously leading to both unwanted behavior and pregnancies. HIGHLIGHTS • Megestrol acetate (11.5 μg/kg/day) is safe and effective for suppression of reproductive activity in queens up to 4 months. • Mammary gland health assessment and a progesterone assay < 2 ng/ml are necessary before initiating treatment. • Queens increase body weight during treatment, but return to pre-treatment weight shortly after the end treatment. • Reproductive activity resumes on average in 6 weeks but is influenced by the duration of treatment and seasonality.
Accidental intravenous overdose of meloxicam in a Cape Vulture (Gyps coprotheres)
(Medpharm Publications, 2025-02) Gazendam, Bart Adriaan Theodorus; Koeppel, Katja Natalie
Many species of vulture are under threat from man-made inventions; this has led to wounded and sick vultures presenting for veterinary treatment and in need of pain management. Following the devastating effect of diclofenac on vultures in South Asia, meloxicam was found to be very safe for vultures, as a treatment as well as through ingestion of meat from treated animals. Many studies investigated the safety of meloxicam, and all found it to be safe up to 2 mg/kg, which was deemed the maximum likely exposure through treated carcasses. All studies exposed the birds either through oral dosing, treated meat or intramuscular administration, no instances of toxicity where recorded and all birds remained healthy. In this case the bird was exposed to a single dose of 2 mg/kg, intravenously, with no signs of toxicity. This appears to be the first recorded instance of accidental intravenous administration of meloxicam in a vulture.
Vaccines in the fight against antimicrobial resistance – perspectives from South Africa
(South African Medical Association, 2024-09) Brink, A.; Kagasi, A.; Musyoki, A.; Kagina, B.; Feldman, C.; Reddy, D..; Du Toit, E.; Kalanxhi, E.; Meyer, J.; Impalli, I.; Schonfeldt, M.; Sibanda, M.; Schellack, Natalie; Skosana, Phumzile; Essack, S.; Dlamini, S.; Ramsamy, Y.
Antimicrobial resistance (AMR), in which microbes adapt to and resist current therapies, is a well-recognised global problem that threatens to reverse gains made by modern medicine in the last decades. AMR is a complex issue; however, at its core, it is driven by the overuse and inappropriate use of antimicrobials. Socioeconomic factors have been identified as significant contributors to the emergence and exacerbation of AMR, especially in populations facing inadequate access to healthcare, poor sanitation services and high morbidity and mortality rates. Weak healthcare systems and water, sanitation and hygiene have been highlighted as fundamental risk factors for AMR emergence and transmission. Behavioural factors, such as purchasing antibiotics without a prescription from a registered healthcare professional, not completing the prescribed course or overly prolonged courses of antibiotics, using antibiotics to treat viral infections, lack of access to quality antibiotics, and the proliferation of substandard or falsified (SF) drugs, have also been identified as significant contributors to AMR. Low- and middle-income countries have a higher incidence of antibiotics being dispensed without a prescription than higher-income countries.
Seasonality, social structure and age predict conspecific aggression in captive breeding southern ground-hornbills (Bucorvus leadbeateri)
(Wiley, 2025-03) Koeppel, Katja Natalie; Lubbe, Nevanya; Donaldson, Ashleigh Claire; Kemp, Lucy Valeska; katja.koeppel@up.ac.za
Southern Ground-hornbills (SGHs) are listed as Vulnerable globally, and Endangered in South Africa, Namibia and Swaziland, due to poisoning, habitat loss and persecution. Successful conservation breeding and rearing of redundant second-hatched chick protocol has been established to supplement natural SGH populations in an attempt mitigate a declining population. However, captive rearing is costly and susceptible to loss of birds through conspecific aggression. Maximising the efficacy of reproductive output in captive settings and ensuring successful reintroductions of captive-reared birds to wild populations is of paramount importance if this species is to persist. Therefore, it is important to untangle the predictors of what drives mortalities in captive birds, particularly, through conspecific aggression. Using a database of captive SGH mortalities collected over 46 years we investigated whether variables such as season, age, relatedness, sex and husbandry predicted the occurrence of conspecific aggression in SGH. Aggression among adult, non-related birds particularly during SGH breeding season (austral spring) was the most predictable form of conspecific aggression. It was inferred that aggression is normally directed at non-related birds outside of already established social groups or at younger, related birds that are not dispersing from groups when reaching sexual maturity. Variables such as season, age, relatedness and husbandry were therefore all useful for predicting the potential and avoidable occurrence of an aggression event. Male birds were most often the aggressors. Making use of such variables to manage birds in a captive setting, move birds before sexual maturity and maintaining birds in known and accepted social structures could greatly improve management in SGH breeding facilities and optimise the efforts for re-establishing natural SGH populations. SUMMARY: Conspecific trauma accounted for approximately 7.80% of all recorded Southern Ground-hornbill (SGH) mortalities. Seasonality significantly influenced aggression, with more attacks in austral spring compared to autumn. Breeding status did not affect aggression frequency; non-breeding individuals were more often involved. Males were not significantly more aggressive than females or pairs, but non-breeding individuals were most aggressive in austral winter and spring. Victim sex or attacker sex did not predict aggression likelihood. Age and sex determined onset of attacks with majority of attacks been adult birds and females (8.8 ± 8.3 years) been attacked earlier then male (9.1 ± 8.9 years). Group size did not significantly influence attack frequency. Moon phase did not affect aggression occurrence.
The role of smallholder pig farmers in the biosecurity of pig diseases in the Eastern Cape Province of South Africa
(Wiley, 2025-05) Simbizi, Vincent; Moerane, Rebone; Gummow, Bruce
Biosecurity forms an important component of preventing disease transmission. However, data on the demographics and practices of smallholder pig farmers in Southern Africa are scant, and little is published on the biosecurity related to these farms. A questionnaire survey was, therefore, carried out in the Eastern Cape Province of South Africa to describe the demographics and practices of smallholder pig farmers and to understand their role in the biosecurity and prevention of pig diseases. Females represented 52% of pig farmers and reflect the cultural importance of pig farming in Xhosa culture. All the farmers who were interviewed had poor biosecurity measures on their farms. A low level of education, lack of training and reliance on remedies to treat and prevent pig diseases were key findings for the majority of farmers. Farmers had a poor knowledge of correct antibiotic use, which could contribute to antimicrobial resistance (AMR). Smallholder farms were found to frequently involve free-ranging pigs, swill feeding and informal trading, practices known to contribute to the spread of communicable pig diseases such as foot and mouth disease and African swine fever. Smallholder pig farms are, therefore, a potential risk for disease incursion and spread of communicable diseases within a region. Cost-effective biosecurity measures and marketing opportunities will help to prevent pig diseases, while a continuing education programme will modernise the rural pig industry and reduce the impact of AMR.
A cross-sectional study of keratoconjunctivitis among dairy cattle farms subject to Mediterranean climatic conditions
(Springer, 2025-03) Maartens, Louis Henning; Thompson, P.N. (Peter N.); Grewar, John Duncan; Picard, Jacqueline; Gummow, Bruce
The epidemiology of bovine keratoconjunctivitis (BK) is complex and involves several conjunctival microbiota as well as host and environmental factors. Data about BK in dairy cattle are scarce, and even scarcer for dairy cattle in Mediterranean climates. We determined the BK prevalence among dairy cattle in Southern Africa’s Mediterranean climatic zone by examining 1,675 dairy cattle across 28 herds. Conjunctival swabs were analysed using real-time PCR. Risk factor data were collected by questionnaire and evaluated by multivariable logistic regression. The BK prevalence was 19.4%, (95% CI: 15.0 – 24.8%). Mesomycoplasma bovoculi was demonstrated in 75.7% of the sampled eyes (95% CI: 62.8 – 85.2%) across all farms. Moraxella bovis (18.3%, 95% CI: 11.9 – 27.0%) and Moraxella bovoculi (8.6%, 95% CI: 4.6 – 15.6%) were detected on 89% and 64% of the farms, respectively. Mycoplasmopsis bovis was rarely encountered. Moraxella bovoculi was significantly associated with BK (OR: 2.7, 95% CI: 1.3 – 5.6, Wald P: 0.01). Prevalence varied significantly by age and breed. Shade availability (OR: 2.5, 95% CI: 1.4 – 4.4, Wald P < 0.01), sanitation frequency, (OR: 0.4, 95% CI: 0.2 – 1.0, Wald P: 0.05), fly burden (OR: 2.1, 95% CI: 1.3 – 3.6, Wald P < 0.01) and introduced cattle (OR: 2.0, 95% CI: 1.1 – 3.5, Wald P: 0.02) were significantly associated with the prevalence of BK. Closed herds with proper biosecurity, fly control via sound management practices, and access to shade are recommended for preventing BK in dairy herds farmed in a Mediterranean climate.
Meeting report : CEPI workshop on Rift Valley fever epidemiology and modeling to inform human vaccine development, Nairobi, 4–5 June 2024
(Elsevier, 2025-04) Gharpure, Radhika; Vegvari, Carolin; Abdissa, Alemseged; Alimi, Yewande; Anyamba, Assaf; Auerbach, Jochen; Bett, Bernard; Bird, Brian H.; Bob, Ndeye Sakha; Breugelmans, J. Gabrielle; Clark, Jessica; Cleaveland, Sarah; Cramer, Jakob; Dawa, Jeanette; Fay, Petra C.; Formenty, Pierre; Gerdts, Volker; Gerken, Keli N.; Gitonga, John; Groschup, Martin; Heighway, James; Johnson, Sherry Ama Mawuko; Juma, John; Kading, Rebekah C.; Kamau, Maureen; Kerama, Samuel; Lubisi, Baratang Alison; Lutwama, Julius; Luyimbazi, Dick; Marami, Dadi; Moore, Sean M.; Muturi, Mathew; Mwangoka, Grace; Ndiu, Angela; Njenga, M. Kariuki; Njouom, Richard; Nyakarahuka, Luke; Nzietchueng, Serge; Oloo, Paul; Otiende, Mark; Oyola, Samuel; Paganini, Lodovico Samuele; Pandit, Pranav S.; Punt, Carine; Samy, Abdallah M.; Situma, Silvia; Sneddon, Heidi; Ten Bosch, Quirine A.; Tezcan-Ulger, Seda; Thompson, P.N. (Peter N.); Tildesley, Mike; Tinto, Bachirou; Vesga, Juan F.; Schreur, Paul P. Wichgers; Hart, Peter
Rift Valley fever (RVF) is a zoonotic viral disease that causes epidemics and epizootics among humans and livestock, resulting in substantial health and socioeconomic consequences. Currently, there are no RVF vaccines licensed for humans, but several candidates show promise in early-stage development. Existing gaps in RVF epidemiological data and challenges associated with predicting RVF outbreak risk complicate the planning of efficacy studies, making the pathway to licensure for promising candidates unclear. In June 2024, the Coalition for Epidemic Preparedness Innovations (CEPI) convened a two-day workshop in Nairobi, Kenya, to discuss RVF epidemiology, modeling priorities, and specific gaps relevant to human RVF vaccine development. The workshop included representatives from multiple RVF-endemic countries, key global collaborators, and international health organizations. Workshop participants identified five key priorities: (1) Looking beyond outbreaks: There is a need to better characterize the complex One Health epidemiology of RVF and understand interepidemic persistence of the virus; (2) Better data for better models: Epidemiological modeling is crucial for research, prediction, and planning, but it requires accurate and representative data; (3) New, improved and accessible diagnostics and serological assays: These are needed to inform epidemiology and case definitions, without which RVF research will continue to suffer due to paucity of data and challenges in determining infection and exposure; (4) Defining use cases, regulatory pathways, and implementation strategies for human vaccines: Clarity on these topics will facilitate licensure and effective use of RVF vaccines; and (5) People-centered approaches: Community engagement and involvement of social and behavioral scientists are key to the success of human vaccine research and development and implementation, particularly as the virus impacts livestock and livelihoods. Workshop participants welcomed a renewed focus for RVF epidemiology and modeling, and expressed enthusiasm for continued multidisciplinary collaborations to support enabling sciences for human RVF vaccine research and development.
Precision feeding of feedlot calves based on phenotypic production profiles I. The effect on economic important production parameters
(MDPI, 2025-05) Hentzen, Andreas H.R.; Holm, Dietmar Erik; andreas.hentzen@up.ac.za
Precision feeding feeder calves according to their production potential could improve economically important production traits. We report two experiments, in two separate locations where feeder calves were categorized into previously established production profiles (PP 1, PP 2, and PP 3). These production-profiled calves were then randomly allocated to a high-producing diet (HPD), medium-producing diet (MPD), or a low-producing diet (LPD). The findings of experiment 1 (n = 430) were used to adjust the formulation of the diets in experiment 2 (n = 104). The mixed modelling of economically important feedlot carcass growth traits was performed in order to evaluate the interactions between PP classification and diet. PP 3 was repeatedly outperformed in all production parameters (p < 0.01) by PP 1 and PP 2, irrespective of the diet. In experiment 1, PP 1 calves outperformed PP 2 and PP 3 calves; however, the HPD was insufficiently matched to their growth potential. In experiment 2 where the metabolizable energy was increased, PP 1 calves gained 23.0 kg more carcass (p = 0.05), at an improved carcass feed conversion of 0.91 kg/kg (p = 0.06), when compared to PP 2 calves on MPD. This is the first report demonstrating the feasibility of precision livestock feeding based on the predicted growth needs of incoming feeder calves as determined by production profiling.
Strategic challenges in the global control of high pathogenicity avian influenza
(Office International des Epizooties, 2024-12) Swayne, D.E.; Sims, L.D.; Brown, R.; Harder, T.; Stegeman, A.; Abolnik, Celia; Delgado, M.; Awada, L.; Pavade, G.; Torres, G.
H5Nx A/Goose/Guangdong/1/96 Eurasian lineage high pathogenicity avian influenza (HPAI) viruses have been the main HPAI strains detected globally since 2005. These have spread around the world, causing a panzootic that has spanned six continents, with continual threat to not only wild and captive birds and poultry, but also wild, captive and domestic mammals and humans. The viruses' ecology and epidemiology - especially the 2.3.4.4b clade - have changed, with over 489 species of birds infected and spreading the virus over migratory routes. This results in the death of many birds, including endangered species, and serves as a source of transmission to poultry and mammals. Improved surveillance and sharing of HPAI virus sequences, metadata and viruses across the veterinary, public health, wildlife and environment sectors are needed to elucidate the population dynamics of the infections, which is crucial to addressing this complex One Health issue. The development of appropriate mitigation strategies or changes in husbandry, production and selling practices can reduce the risk of viruses being introduced into farms, as well as their amplification and viral evolution, and any spill-back to wild birds. Approaches to prevention and control of HPAI in countries where these 2.3.4.4b viruses remain entrenched in poultry, or places at risk of virus introduction via wild bird populations, involve measures to reduce the effects of the disease in poultry (including enhanced farm bio-security, vaccination, zoning and compartmentalisation). Their uptake reflects the difficulties encountered in relying solely on biosecurity for disease prevention and on stamping out alone for virus control and elimination. The World Organisation for Animal Health's Terrestrial Animal Health Code allows use of vaccination of poultry under specific conditions and without negatively impacting HPAI-free status if appropriate surveillance is conducted, thus supporting safe trade in poultry and poultry products. Nevertheless, concerns regarding loss of valuable export markets still interfere with greater utilisation of vaccination.
A One Health approach to reducing livestock disease prevalence in developing countries : advances, challenges, and prospects
(Annual Reviews, 2025-02) Lane, Jennifer K.; Kelly, Terra; Bird, Brian; Chenais, Erika; Roug, Annette; Vidal, Gema; Gallardo, Rodrigo; Zhou, Huaijun; Vanhoy, Grace; Smith, Woutrina
Challenges in livestock production in developing countries are often linked to a high disease prevalence and may be related to poor husbandry, feeding, and nutrition practices, as well as to inadequate access to preventive veterinary care. Structural barriers including chronic poverty, gender roles, inadequate supply chains, and limitations in surveillance infrastructure further complicate progress. Despite many challenges, the livestock sector substantially contributes to agricultural GDP, and reducing livestock disease prevalence is a goal for many countries. One Health initiatives that work across disciplines and sectors to reduce livestock diseases are underway around the world and use integrated approaches that consider the connections between humans, animals, and their shared environments. The growing recognition of the role livestock play in sustainability and livelihoods, as well as their involvement in zoonotic disease transmission and global health security, has highlighted the need for disease reduction strategies as described in this review.
The potential of various phenotypic traits to predict feedlot production in cattle - a systematic review
(CSIRO Publishing, 2025-05) Hentzen, Andreas H.R.; Holm, Dietmar Erik; dietmar.holm@up.ac.za
CONTEXT : Visual evaluation of phenotypic traits is an old and still practiced management tool in the beef industry. Beef production has improved because of the constant visual re-evaluation of phenotypic traits that are associated with production. Current data exposed the need to put all existing knowledge together in context. AIMS : This literature review is to determine the value of individual predictor variables based on existing knowledge, with the view of further improving, expanding, and refining the measured traits. METHODS : This systematic literature review focused on phenotypic traits and their potential associations with production. The traits needed to be predictive in nature. We particularly focused on studies involving intensive production systems, such as feedlots. A search of keywords related to the topic was performed on published articles and textbooks. This included textbooks from the seed stock industry. KEY RESULTS : Several, but not all, studies have demonstrated a positive association between phenotypic cattle traits and subsequent feedlot performance. The sensitivity of the measurement varied. The phenotypic traits investigated were either visually appraised and/or linearly measured. Studies focused on muscle and skeletal development because of their contribution to growth. Specific phenotypic traits were investigated, rather than a more holistic approach and/or combination thereof. For example, two different studies evaluated the predictive ability of dimensions of the cannon bone: one investigating the circumference and another the length. CONCLUSION : The consulted literature revealed limited evidence that phenotypic traits of incoming feeder calves can predict feedlot production. The current information needs more structure and refinement in measurement and reporting to find its application in a beef feedlot operation. IMPLICATIONS : A structured phenotypic evaluation before onset of the feeding phase in beef feedlots carries numerous advantages in beef production. The potential of precision feeding calves to phenotypically established production-related profiles can result from this study.
Vaccination and surveillance for high pathogenicity avian influenza in poultry-current situation and perspectives
(Elsevier, 2025-08) Sajjadi, Nancy C.; Abolnik, Celia; Baldinelli, Francesca; Brown, Ian; Cameron, Angus; De Wit, Sjaak; Dhingra, Madhur; Espeisse, Olivier; Guerrin, Jean Luc; Harder, Timm; Ho, Jeremy; Chua, Tze-Hoong; Hussein, Khaled; Lyons, Nicholas; Monne, Isabella; Okamuro, Yukitake; Pacheco, Damian Tago; Pavade, Gounalan; Poncon, Nicolas; Prajitno, Teguh Yodiantara; Rojas, Jose Gonzales; Swayne, David; Stegeman, Arjan
The International Alliance for Biological Standardization (IABS), in collaboration with the World Organization for Animal Health (WOAH) convened a hybrid meeting on 22–23 October 2024 at the WOAH Headquarters (HQ) in Paris, France to discuss the global state of vaccination and surveillance for high pathogenicity avian influenza (HPAI) in poultry. The primary objective of the meeting was to advance vaccination acceptance to both control virus spread and reduce disease. Vaccination is increasingly recognized as a tool to complement biosecurity, movement controls and stamping-out of infected flocks. However, concerns persist regarding the risk of undetected, sustained transmission (silent infection) in vaccinated flocks as a result of inadequate surveillance. This has contributed to both vaccination hesitancy and trade barriers. The meeting aimed to assess the current state of the art regarding HPAI surveillance programs in vaccinated populations and their effectiveness. Representatives of multiple stakeholders were invited to share their experiences and perspectives on the use of vaccination and accompanying surveillance to control the growing H5N1 panzootic and its global impact. Several conclusions and recommendations emerged as essential to advancing the acceptance of vaccination strategies. These included (1) the utility of quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) as a sensitive, specific and economical tool to detect virus in vaccinated populations, (2) regular testing of dead birds within a flock as a highly effective method for early detection of outbreaks in vaccinated flocks and demonstrating freedom from infection and, (3) the importance of collecting information on circulating field strains in the selection of candidate vaccine antigens to ensure adequate efficacy. Testing sentinel birds was deemed less effective for surveillance and serological testing of vaccinated birds was considered more useful for assessing immunity levels than for determining the infection status of a flock. There was broad agreement on the need to standardize surveillance outcomes in terms of accepted confidence levels to promote safe and fair trade. However, it was acknowledged that context and pragmatic considerations will shape the development of situation specific plans, which must be statistically valid, scientifically sound, economically feasible and operationally sustainable for both governments and industry. Concomitantly, it was recommended that trade policies tied to vaccination and surveillance should be based solely on science and risks. To this end, enforcement of existing international rules and resolution of disputes are considered a shared responsibility. Peer reviewed publications were proposed as a central mechanism for developing the stronger guidelines needed to facilitate fair trade agreements and enable implementation of global vaccination programs. Rapid dissemination of information, consistent messaging and exchange of virus isolates were also seen as critical for coordinating an effective global response to controlling HPAI.
WSAVA guidelines for the control of reproduction in dogs and cats
(World Small Animal Veterinary Association (WSAVA), 2024-07) Romagnoli, S.; Krekeler, N.; De Cramer, Kurt Guido Mireille; Kutzler, M.; McCarthy, R.; Schaefer-Somi, S.
No abstract available.
Evidence-based guidelines for the post-fire assessment of domestic ruminants : a scoping review
(BioMed Central, 2025-03) Cardoso, Claudia L.; May, Catherine Edith; Leask, Rhoda; claudia.cardosocamaiti@up.ac.za
Wildfires globally impact farmers, with risk expected to rise in the next thirty years. Beyond fatalities, wildfires impair the reproductive capabilities of surviving livestock due to smoke exposure. Effective interventions require considering animal welfare, prognosis, and costs. Enhanced clinical assessment is crucial. There is a paucity of data concerning decision-making processes regarding burn injuries in livestock. This study establishes evidence-based guidelines for wildfire-affected ruminants in field settings. The goal is categorizing scientific evidence to create prognostic guidelines. English and Spanish publications from Web of Science, Medline, and Google Scholar were searched using keywords related to burn injuries, disaster management, and animal welfare. A research matrix was populated based on inclusion criteria and evidence strength, leading to the development of visual triage guidelines for sheep and cattle. Most evidence comprises case reports (expert opinion) and observational trials. Ovine controlled trials in the 80 s and 90 s significantly advanced burn injury understanding in humans and animals. Key clinical factors determining burn severity include burn extent and depth, anatomic location, and smoke inhalation. Core non-clinical factors implicated in decision-making include feed, water, and shelter, amongst others. Animal categorization by burn severity creates a model for prioritising resources towards animals with the best recovery chances, protecting animal welfare.
A Bayesian latent class estimation of the diagnostic accuracy of clinical examination and laboratory assays to identify bovine ephemeral fever virus infection in South African cattle
(Elsevier, 2025-06) Grobler, Miemie; Fosgate, Geoffrey Theodore; Swanepoel, Robert; Crafford, Jan Ernst; miemie.grobler@up.ac.za
Bovine ephemeral fever (BEF) is an economically important vector-borne viral disease of cattle and water buffalo in Africa, Australia and parts of Asia. The control of BEF is centred around vaccination, and therefore accurate, early identification of disease outbreaks are key to minimize its economic and welfare impact. In Africa, control programs are hampered by limited diagnostic capabilities and poor infrastructure for rapid transportation of diagnostic specimens. The primary objective of this study was to estimate the sensitivity (Se) and specificity (Sp) of four tests, namely clinical examination by a veterinarian, virus isolation and two different conventional PCR assays, to identify an acute bovine ephemeral fever virus (BEFV) infection in diseased, naturally infected South African cattle, without the assumption of a reference standard. Samples and data were collected from cattle with clinical signs suggestive of BEF rather than a random sample of cattle. A case was categorised as clinical examination positive if the examining veterinarian considered acute BEFV-infection as the most likely aetiology. Virus isolation was performed using the buffy coat of heparin blood samples on baby hamster kidney cell cultures, evaluating cytopathic effect and confirming virus morphology by transmission electron microscopy. PCR was performed using two previously published protocols: The Ephemerovirus L-gene PCR (targeting the RNA-dependent RNA polymerase gene) and a BEFV G-gene PCR (targeting the neutralising G1 epitope of the glycoprotein). A single population, four test Bayesian latent class model with conditional dependence between the two PCR assays was implemented. The prevalence of BEFV-infection was high in this study population of clinical suspects at 67 %, (95 % Probability Interval (PI) 52 %; 81 %). Clinical examination provided a reasonable indication of acute BEFV infection (Se of 86 % (PI 77 %; 93 %) and Sp of 67 % (PI 52 %; 82 %)). Virus isolation was the most specific (99 % (PI 97 %; 100 %)), but least sensitive assay (30 % (PI 20 %; 44 %)). Of the two conventional PCRs, the L-gene PCR outperformed the G-gene PCR: The L-gene Se was 64 % (PI 51 %; 76 %) and Sp 96 % (PI 84 %; 100 %) compared to Se of 50 % (PI 38 %; 61 %) and Sp of 89 % (PI 75 %; 98 %) for the G-gene. While the laboratory assays presented excellent positive predictive values within this high disease prevalence population, the poor negative predictive values limit their usefulness to field veterinarians attempting to exclude BEF as diagnosis. Novel pen-side diagnostics should be developed due to the limitations of currently available assays and infrastructure constraints prevalent in Africa.
Assessment of communal farmers' knowledge of foot-and-mouth disease (FMD) within the FMD protection zone with vaccination of Limpopo and Mpumalanga Provinces, South Africa
(Elsevier, 2025-05) Kiayima, Kibambe D.; Etter, Eric Marcel Charles; Chaminuka, Petronella; Delabouglise, Alexis; Fosgate, Geoffrey Theodore
Foot-and-mouth disease (FMD) is a highly contagious disease affecting domestic livestock and its control in South Africa depends on methods including event-based surveillance and the reporting of disease by farmers. This study assessed FMD knowledge level among small-scale, communal livestock farmers in South Africa's FMD zone with vaccination. A cross-sectional study was conducted with 629 farmers from 44 dip-tanks (animal assembly points). A FMD knowledge score was derived from 25 yes/no questions with scores above the median classified as high FMD knowledge. Mixed-effects logistic regression was used to evaluate predictors of high FMD knowledge with associations reported as odds ratios (OR) and their corresponding 95 % confidence intervals (CI). Eighty percent of the participants were male and 65 % aged 60 or older. The most common livestock raised was cattle (98.1 %). Sixty-six percent (415/629) of the interviewed farmers reported that they were aware of the existence of FMD. Formal education (OR 2.0, 95 % CI, 1.4–2.9, P < 0.001), poultry ownership (OR 1.7, 95 % CI 1.1–2.5, P = 0.006), livestock farming as the main occupation (OR 1.6, 95 % CI 1.1–2.3, P = 0.026) and the total livestock units of their farm (OR 1.5, 95 % CI 1.1–1.9, P = 0.002) were significant predictors of FMD recognition. Most respondents (54 %) that claimed to be aware of the existence of FMD did not know that African buffalos were a source of FMD virus. Also, less than half of the respondents cited lameness (38 %) and excessive salivation (37 %) as the main FMD clinical signs. Only a small proportion (2.4 %) of these respondents were aware that movement of infected animals can cause FMD virus to spread to new areas. FMD knowledge scores were calculated for the 415 respondents claiming to be aware of the existence FMD with 174 (42 %) having a total knowledge score greater than the median (hereafter referred to as “high FMD knowledge” compared to the rest of the farmers). Farmers from Vhembe District in Limpopo had an odds of high FMD knowledge four times higher than those in Ehlanzeni District in Mpumalanga (OR 4.0, 95 % CI 1.7–9.4, P = 0.002). Farmers that owned more than 15 cattle (OR 1.7, 95 % CI 1.0–2.8, P = 0.035) and farmers that supervised their own cattle during grazing (OR 1.6, 95 % CI 1.0–2.5, P = 0.043) also had a significantly higher odds of high FMD knowledge. Communal farmers in South Africa have gaps in their FMD knowledge and specifically were not aware that movement of infected animals and their products pose a threat for the spread of FMD. Comprehensive information, education and training for communal livestock farmers are essential for improving event-based surveillance and FMD prevention and control in the region.
Antimicrobial resistance profiles of Listeria species recovered from retail outlets in Gauteng Province, South Africa
(Elsevier, 2024-08) Gana, James; Gcebe, Nomakorinte; Moerane, Rebone; Ngoshe, Yusuf Bitrus; Tshuma, Tsakula; Moabelo, Khomotso C.; Adesiyun, Abiodun Adewale; abiodun.adesiyun@up.ac.za
The study determined the antimicrobial resistance (AMR) profiles of Listeria spp. (L. monocytogenes, L. innocua, and L. welshimeri) recovered from beef and beef products sold at retail outlets in Gauteng Province, South Africa. A total of 112 isolates of Listeria spp., including L. monocytogenes (37), L. innocua (65), and L. welshimeri (10), were recovered from beef and beef products collected from 48 retail outlets. Listeria spp. was recovered by direct selective plating following selective enrichment, and PCR was used to confirm and characterize recovered isolates. The disc diffusion method determined the resistance to 16 antimicrobial agents. All 112 isolates of Listeria spp. exhibited resistance to one or more antibiotics (P < 0.05). The prevalence of AMR in Listeria isolates was high for nalidixic acid (99.1%) and cefotaxime (80.4%) but low for gentamycin (2.7%), sulfamethoxazole‐trimethoprim (3.6%), azithromycin (5.4%), and doxycycline (6.3%). Overall, for the three species of Listeria, the prevalence of resistance varied significantly only for streptomycin (P=0.016) and tetracycline (P = 0.034). Multidrug‐resistant isolates were detected in 75.7% (28/37), 61.5% (40/65), and 80% (8/10) isolates of L. monocytogenes, L. innocua, and L. welshimeri, respectively. The prevalence of AMR was significantly affected by the location and size of retail outlets, type of beef and beef products, and serogroups of L. monocytogenes. The high prevalence of AMR, particularly among the L. monocytogenes isolates, poses potential therapeutic implications for human consumers of contaminated beef products. There is, therefore, a need to regulate and enforce the use of antimicrobial agents in humans and animals in South Africa.
Molecular characterization of virulence and resistance genes in Salmonella strains isolated from chickens sold at the informal chicken market in Gauteng Province, South Africa
(Wiley, 2024-04) Mokgophi, Thelma M.; Gcebe, Nomakorinte; Fasina, Folorunso Oludayo; Adesiyun, Abiodun Adewale
This cross-sectional study determined the occurrence of virulence and antimicrobial resistance genes in Salmonella strains recovered from chicken obtained from informal markets in Gauteng province, South Africa. The study also assessed the relationship between these characteristics, the source, the type of samples, and the serotypes of Salmonella isolates. A total of 151 samples (cloacal swabs, chicken carcasses, and carcass drips) were randomly collected from 47 informal market outlets in six townships in Gauteng province. Salmonella spp. was isolated and identified based on ISO 6579:2002 methods and confirmed by polymerase chain reaction (PCR) targeting invA gene fragment. Conventional PCR was used to detect 12 virulence and 18 antimicrobial resistance (AMR) genes in Salmonella spp. The most frequently detected virulence genes were invA (100%), shdA (91%), mgtB (87.7%), and sopE (81%), but considerably low for spvC (2.2%), sefC (1.5%), and pefC (0.4%). The differences in detection frequency were statistically significant (p < 0.05). Tetracycline-resistant genes tetA (34.7%) and tetB (16%) were the most frequently detected, while Betalactam- resistant genes blaTEM (0.4%), blaCMY-2 (0.4%) and quinolones resistant gene qnrS (0.4%) were detected in low frequency (p < 0.05). The locations of the outlets and the types of samples were significantly associated with detecting some virulence and AMR genes. Significant but moderately to substantial positive correlations were observed for qnrS, sul2; shdA, and mgtB genes. The pipA and spiC were, however, substantially negatively correlated. Our findings show that detecting these virulence and AMR genes in Salmonella isolates serves as a potential health hazard to the public, environment, and poultry farming in Gauteng, South Africa.
Closed laceration of the trachea, esophagus and guttural pouches in a mare caused by blunt trauma
(Elsevier, 2024-12) Lopes, M.A.F.; Hollenbach, Elza; Schliewert, Eva-Christina; Murphy, Mark-Anthony; Correa, Felipe
A mare was admitted for progressive swelling of the neck, lethargy and anorexia. Radiography revealed perilaryngeal, peritracheal, and periesophageal emphysema. Endoscopy revealed pharyngeal and tracheal roof collapse, and a small laceration on the trachea. Treatment with antimicrobials, fluids, and flunixin was initiated. To prevent exacerbation of the emphysema, temporary tracheostomy was performed. Clipping for the tracheostomy revealed a hoofprint mark on the ventral neck. Subsequent endoscopies revealed laceration of the esophagus and guttural pouch septum communicating with the visceral compartment of the neck. Four days after admission, an esophagostomy was performed to prevent leakage of ingesta into the neck and allow feeding. Complications occurred: Deep cervical infection requiring surgical drainage; Esophageal impaction with shavings on one occasion causing extensive mucosa erosions; Laminitis managed with restricted physical activity and corrective farriery. Tracheostomy tube removal, esophagostomy tube removal, and patient discharge occurred 10, 36 and 51 days after admission, respectively. The mare did well after discharge and returned to competing in children’s showing classes. Blunt trauma to the neck can lacerate the trachea, esophagus and guttural pouches causing emphysema and deep cervical infection, which can be treated with antimicrobials, temporary tracheostomy, temporary esophagostomy, surgical drainage, and supportive care.
Evidence for horizontal transmission and recirculation of Shiga toxin-producing Escherichia coli in the beef production chain in South Africa using whole genome sequencing
(MDPI, 2024-09) Onyeka, L.O. (Libby); Adesiyun, Abiodun Adewale; Ismail, Arshad; Allam, Mushal; Keddy, Karen H.; Thompson, P.N. (Peter N.); peter.thompson@up.ac.za
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