West Nile virus infection of Thoroughbred horses in South Africa (2000-2001)

A. J. Guthrie, P. G. Howell, Ian Gardner, R. E. Swanepoel, J. P. Nurton, C. K. Harper, A. Pardini, D. Groenewald, C. W. Visage, J. F. Hedges, U. B. Balasuriya, A. J. Cornel, Nigel J Maclachlan

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Reasons for performing study: West Nile virus (WNV) infection is endemic in southern Africa. With the recent emergence of WNV infection of horses in Europe and the USA the present study was performed to estimate the risk of seroconversion to WNV in a cohort of 488 young Thoroughbred (TB) horses. Objectives: To estimate the risk of seroconversion to WNV among a cohort of South African TB yearlings sold at the 2001 National Yearling Sales (NYS) and to determine whether the risk varied geographically. Two horses were also infected with a recent South African isolate of WNV to evaluate its virulence in horses. Methods: Serum samples were collected from the cohort of 488 TB yearlings at the 2001 NYS. Serum samples that were collected from the same horses at the time that they were identified were sourced from our serum bank. Sera from 243 of the dams that were collected at the time that the foals were identified were also sourced from our serum bank. These sera were subjected to serum neutralisation (SN) tests for antibody to WNV. Results: Approximately 11% of yearlings seroconverted to WNV on paired serum samples collected from each animal approximately 12 months apart. Studfarms with WNV-seropositive yearlings were widely distributed throughout South Africa and SN tests on sera from their dams indicated that exposure to WNV was even more prevalent (75%) in this population. Neurological disease was not described in any of the horses included in this study and 2 horses inoculated with a recent lineage 2 South African isolate of WNV showed no clinical signs of disease after infection and virus was not detected in their blood. Conclusions: Infection of horses with WNV is common in South Africa, but infection is not associated with neurological disease. Potential relevance: In contrast to recent reports from Europe, North Africa, Asia and North America, the results of our field and experimental studies indicated that exposure of horses to the endemic southern African strains of WNV was not associated with neurological disease.

Original languageEnglish (US)
Pages (from-to)601-605
Number of pages5
JournalEquine Veterinary Journal
Volume35
Issue number6
StatePublished - Sep 2003

Fingerprint

West Nile virus
Virus Diseases
South Africa
Horses
blood serum
horses
yearlings
infection
Serum
Neutralization Tests
risk estimate
seroconversion
neutralization tests
sales
Northern Asia
Southern Africa
Northern Africa
North America
Infection
foals

Keywords

  • Epidemiology
  • Horse
  • Risk factors
  • Serology
  • West Nile virus

ASJC Scopus subject areas

  • veterinary(all)

Cite this

Guthrie, A. J., Howell, P. G., Gardner, I., Swanepoel, R. E., Nurton, J. P., Harper, C. K., ... Maclachlan, N. J. (2003). West Nile virus infection of Thoroughbred horses in South Africa (2000-2001). Equine Veterinary Journal, 35(6), 601-605.

West Nile virus infection of Thoroughbred horses in South Africa (2000-2001). / Guthrie, A. J.; Howell, P. G.; Gardner, Ian; Swanepoel, R. E.; Nurton, J. P.; Harper, C. K.; Pardini, A.; Groenewald, D.; Visage, C. W.; Hedges, J. F.; Balasuriya, U. B.; Cornel, A. J.; Maclachlan, Nigel J.

In: Equine Veterinary Journal, Vol. 35, No. 6, 09.2003, p. 601-605.

Research output: Contribution to journalArticle

Guthrie, AJ, Howell, PG, Gardner, I, Swanepoel, RE, Nurton, JP, Harper, CK, Pardini, A, Groenewald, D, Visage, CW, Hedges, JF, Balasuriya, UB, Cornel, AJ & Maclachlan, NJ 2003, 'West Nile virus infection of Thoroughbred horses in South Africa (2000-2001)', Equine Veterinary Journal, vol. 35, no. 6, pp. 601-605.
Guthrie AJ, Howell PG, Gardner I, Swanepoel RE, Nurton JP, Harper CK et al. West Nile virus infection of Thoroughbred horses in South Africa (2000-2001). Equine Veterinary Journal. 2003 Sep;35(6):601-605.
Guthrie, A. J. ; Howell, P. G. ; Gardner, Ian ; Swanepoel, R. E. ; Nurton, J. P. ; Harper, C. K. ; Pardini, A. ; Groenewald, D. ; Visage, C. W. ; Hedges, J. F. ; Balasuriya, U. B. ; Cornel, A. J. ; Maclachlan, Nigel J. / West Nile virus infection of Thoroughbred horses in South Africa (2000-2001). In: Equine Veterinary Journal. 2003 ; Vol. 35, No. 6. pp. 601-605.
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abstract = "Reasons for performing study: West Nile virus (WNV) infection is endemic in southern Africa. With the recent emergence of WNV infection of horses in Europe and the USA the present study was performed to estimate the risk of seroconversion to WNV in a cohort of 488 young Thoroughbred (TB) horses. Objectives: To estimate the risk of seroconversion to WNV among a cohort of South African TB yearlings sold at the 2001 National Yearling Sales (NYS) and to determine whether the risk varied geographically. Two horses were also infected with a recent South African isolate of WNV to evaluate its virulence in horses. Methods: Serum samples were collected from the cohort of 488 TB yearlings at the 2001 NYS. Serum samples that were collected from the same horses at the time that they were identified were sourced from our serum bank. Sera from 243 of the dams that were collected at the time that the foals were identified were also sourced from our serum bank. These sera were subjected to serum neutralisation (SN) tests for antibody to WNV. Results: Approximately 11{\%} of yearlings seroconverted to WNV on paired serum samples collected from each animal approximately 12 months apart. Studfarms with WNV-seropositive yearlings were widely distributed throughout South Africa and SN tests on sera from their dams indicated that exposure to WNV was even more prevalent (75{\%}) in this population. Neurological disease was not described in any of the horses included in this study and 2 horses inoculated with a recent lineage 2 South African isolate of WNV showed no clinical signs of disease after infection and virus was not detected in their blood. Conclusions: Infection of horses with WNV is common in South Africa, but infection is not associated with neurological disease. Potential relevance: In contrast to recent reports from Europe, North Africa, Asia and North America, the results of our field and experimental studies indicated that exposure of horses to the endemic southern African strains of WNV was not associated with neurological disease.",
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AU - Nurton, J. P.

AU - Harper, C. K.

AU - Pardini, A.

AU - Groenewald, D.

AU - Visage, C. W.

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