A study of leptospirosis in South African horses and associated risk factors.
Abstract: Most leptospiral infections in horses are asymptomatic; however, acute disease manifestations as well as reproductive failure and recurrent uveitis have been reported. In South Africa, the epidemiology of the disease in horses is not well documented. A serosurvey to determine what serovars were present in horses from Gauteng, KwaZulu-Natal and Western Cape Provinces and to get an estimate of the seroprevalence of leptospirosis was carried out from January 2013 until April 2014 with the assistance of four large equine hospitals located in these provinces. Furthermore, associations between potential risk factors and both seropositive horses to the predominant serovar Bratislava and to Leptospira spp. were statistically evaluated using univariate analysis and multivariable logistic regression models. A total of 663 horse sera were collected and tested against a panel of 24 leptospiral serovars using the microscopic agglutination test. The most predominant serovars in Gauteng were Bratislava [32%, 95% CI: 29-35%]; Djasiman [10.4%, 95% CI: 8-12%] and Arborea [8.9%, 95% CI: 7-11%], in the Western Cape Province, Bratislava [27.35%, 95% CI: 23-32]; Djasiman [15.4%, 95% CI: 12-19%] and Arborea [14.5%, 95% CI: 11-18%] and in KwaZulu-Natal, Bratislava [39.4%, 95% CI: 34-44%]; Arborea [9.6%, 95% CI: 7-13%]; and Tarassovi [7.7%, 95% CI: 5-10%] respectively. Twenty one serovars representing 17 serogroups were detected with serovar Bratislava being the most serodominant. The apparent prevalence to one or more serovars of Leptospira spp. at a serum dilution of 1:100 in Gauteng, KwaZulu-Natal and Western Cape Provinces were 49%; 37% and 32% respectively. The true prevalence was calculated for each province taking into account the clustering effect during the sampling and was found to be between 24 and 74% in Gauteng; 26-39% in the Western Cape and 20-54% in KwaZulu-Natal. Nooitgedacht (South African horse breed) horses were found to be at greater risk of being seropositive to both serovar Bratislava (OR=5.08) and Leptospira spp. (OR=6.3). Similarly, horses residing on properties with forestry in the vicinity were found to be at greater risk of being seropositive to both serovar Bratislava (OR=9.3) and Leptospira spp. (OR=5.2). This study has shown that a high proportion of horses in South Africa are exposed to a wide range of serovars, inferring a complex epidemiology. It also describes for the first time new serovars of Leptospira in South African horses that have not previously been reported.
Copyright © 2016 Elsevier B.V. All rights reserved.
Publication Date: 2016-09-24 PubMed ID: 27836047DOI: 10.1016/j.prevetmed.2016.09.019Google Scholar: Lookup
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- Journal Article
Summary
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The research conducted a study on leptospirosis in horses within specific areas of South Africa, determining prevalent serovars and assessing potential risk factors for the condition.
Objective of the Study
- The aim of the study was to understand the epidemiology of leptospirosis in horses across Gauteng, KwaZulu-Natal, and Western Cape Provinces of South Africa.
- The researchers sought to identify verifiable serovars present in horses in these regions and to estimate the prevalence of leptospirosis.
Methodological Approach
- The researchers carried out a serosurvey from January 2013 to April 2014, with help from four large horse hospitals in these provinces.
- A total of 663 horse sera were collected and tested using the microscopic agglutination test against a panel of 24 leptospiral serovars.
- The researchers used statistical tools such as univariate analysis and multivariable logistic regression models to evaluate potential risk factors associated with leptospirosis occurrence.
Findings of the Study
- The most common serovars discovered in the Provinces were Bratislava, Djasiman, and Arborea, with Bratislava being the most predominant.
- The realized prevalence of one or more leptospiral serovars in the horse populations in these provinces ranged between 32% and 49%.
- The calculated “true prevalence”, accounting for sample bias, varied between 20% and 74% depending on the province.
- Potential risk factors for leptospirosis were identified, such as the breed of the horse (Nooitgedacht horses were more susceptible) and the presence of local forestry.
Significance of the Findings
- This study shows a high proportion of horses in these South African provinces are exposed to multiple serovars of leptospirosis, suggesting a complex epidemiology in the area.
- The work also reports previously unknown serovars of Leptospira in South African horses for the first time.
- The identification of specific risk factors provides a foundation for developing measures to prevent and control the spread of the disease in the local horse population.
Cite This Article
APA
Simbizi V, Saulez MN, Potts A, Lötter C, Gummow B.
(2016).
A study of leptospirosis in South African horses and associated risk factors.
Prev Vet Med, 134, 6-15.
https://doi.org/10.1016/j.prevetmed.2016.09.019 Publication
Researcher Affiliations
- State Veterinary Services, Department of Rural Development and Agrarian Reform, Lady Frere, South Africa; Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.
- Winelands Equine Vet, Stellenbosch, South Africa.
- Bacterial Serology Laboratory: ARC-Onderstepoort Veterinary Institute, Onderstepoort, South Africa.
- Bacterial Serology Laboratory: ARC-Onderstepoort Veterinary Institute, Onderstepoort, South Africa.
- Discipline of Veterinary Sciences, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville 4811, Queensland, Australia; Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa. Electronic address: bruce.gummow@jcu.edu.au.
MeSH Terms
- Agglutination Tests / veterinary
- Animals
- Female
- Horse Diseases / epidemiology
- Horse Diseases / microbiology
- Horses
- Leptospira / genetics
- Leptospira / physiology
- Leptospirosis / epidemiology
- Leptospirosis / microbiology
- Leptospirosis / veterinary
- Male
- Prevalence
- Risk Factors
- Seroepidemiologic Studies
- Serogroup
- South Africa / epidemiology
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