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The Canadian veterinary journal = La revue veterinaire canadienne2007; 48(11); 1137-1145;

Factors associated with West Nile virus disease fatalities in horses.

Abstract: In 2003, the occurrence and location of horses with clinical signs of West Nile virus infection were identified in the southern portion of Saskatchewan with the help of veterinarians, owners, and the regional laboratory. A total of 133 clinical cases were reported between July 30 and September 19, 2003; however, postseason surveillance suggests that the number of cases was underestimated. The case fatality rate was 43.8% (95% CI 35.2, 52.4). Factors associated with fatality in clinical cases included sex, week of onset of clinical signs, and coat color. Reported clinical cases clustered within regional health authority districts, suggesting regional differences in geographic factors, potentially including climate and mosquito control, that could contribute to the risk of disease. However, most of the variation in the risk of fatality in clinical cases is explained at the individual level rather than the Regional Health Authority level, which suggests the outcome of clinical disease is primarily determined by characteristics of, or management factors affecting, the individual horse. En 2003, l’apparition des signes cliniques d’infection au virus du Nil occidental chez les chevaux et le lieu où ils étaient situés ont été identifiés dans le sud de la Saskatchewan avec l’aide des vétérinaires, des propriétaires et du laboratoire régional. Un total de 133 cas cliniques ont été rapportés entre le 30 juillet et le 19 septembre 2003 et les observations de fin de saison laissent présager que le nombre de cas a été sous-estimé. Le taux de mortalité était de 43,8 % (95 % IC 35,2, 52,4). Les facteurs associés à la mortalité dans les cas cliniques comprenaient le sexe, la semaine du début des signes cliniques et la couleur de la robe. Les cas cliniques rapportés étaient regroupés dans certains districts des autorités régionales de la santé, laissant présager des différences régionales dans les facteurs géographiques, dont le climat et le contrôle des moustiques, qui auraient pu affecter le facteur de risque. Cependant, la majorité de la variation du risque de mortalité dans les cas cliniques semble relié à l’individu plutôt qu’aux autorités régionales de la santé, ce qui laisse présager que l’apparition des cas cliniques est en majeure partie déterminée par des caractéristiques propres à l’animal ou par des facteurs de gestion qui l’influence. (Traduit par Docteur André Blouin)
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Publication Date: 2007-12-07 PubMed ID: 18050794PubMed Central: PMC2034420
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research investigates factors associated with fatalities in horses due to West Nile virus in Saskatchewan in 2003. The study found that sex, timing of clinical symptoms onset, and coat color were factors that influenced fatality rates, most of which could be attributed to individual characteristics or management practices affecting each horse.

Study Overview

The study aimed to identify the factors influencing West Nile virus fatalities in horses by evaluating demographics, onset of symptoms, and geographic factors. Key points included:

  • The study took place in the southern part of Saskatchewan in 2003.
  • The information was gathered with the assistance of veterinarians, horse owners, and the regional laboratory.
  • The research was conducted during the WNV infection season, between July 30 and September 19.
  • Surveillance data indicated that the total number of cases reported (133) was likely an underestimate.

Case Fatality and Associated Factors

From the reported cases, a high rate of fatality (43.8%) was observed. The different factors associated with horse fatalities were identified as:

  • The horse’s sex
  • The week when the clinical signs were first noticed
  • The horse’s coat color

Role of Geographic Factors

Reports showed that cases were notably concentrated within certain regional health authority districts. This suggests that geographical factors such as:

  • Regional climate conditions
  • Effective mosquito control

may have influenced the risk and spread of the disease.

Individual Horse Characteristics & Management Practices

The study concluded that most of the variation in the risk of fatality was tied to individual-level factors rather than regional factors. This suggests that the outcome of the disease, in most cases, was primarily determined by:

  • The characteristics of the individual horse – its sex, coat color etc.
  • Management factors affecting the horse – how the horse was taken care of once the symptoms were detected.

Cite This Article

APA
Epp T, Waldner C, West K, Townsend H. (2007). Factors associated with West Nile virus disease fatalities in horses. Can Vet J, 48(11), 1137-1145.

Publication

The Canadian veterinary journal = La revue veterinaire canadienne
ISSN: 0008-5286
NlmUniqueID: 0004653
Country: Canada
Language: English
Volume: 48
Issue: 11
Pages: 1137-1145

Researcher Affiliations

Epp, Tasha
  • Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan. tasha.epp@usask.ca
Waldner, Cheryl
    West, Keith
      Townsend, Hugh

        MeSH Terms

        • Animal Husbandry / methods
        • Animals
        • Antibodies, Viral / blood
        • Breeding
        • Cluster Analysis
        • Female
        • Horse Diseases / epidemiology
        • Horse Diseases / mortality
        • Horses
        • Male
        • Mosquito Control
        • Risk Factors
        • Saskatchewan / epidemiology
        • Seasons
        • Seroepidemiologic Studies
        • Sex Factors
        • West Nile Fever / epidemiology
        • West Nile Fever / mortality
        • West Nile Fever / veterinary
        • West Nile virus / immunology
        • West Nile virus / isolation & purification

        References

        This article includes 22 references
        1. Hayes C. West Nile fever. .
        2. Smithburn KC, Hughes TP, Burke AW, Paul JH. A neurotropic virus isolated from the blood of a native of Uganda. Am J Trop Med 1940;20:471–492.
        3. Hubálek Z, Halouzka J. West Nile fever--a reemerging mosquito-borne viral disease in Europe.. Emerg Infect Dis 1999 Sep-Oct;5(5):643-50.
          pmc: PMC2627720pubmed: 10511520doi: 10.3201/eid0505.990505google scholar: lookup
        4. Murgue B, Murri S, Zientara S, Durand B, Durand JP, Zeller H. West Nile outbreak in horses in southern France, 2000: the return after 35 years.. Emerg Infect Dis 2001 Jul-Aug;7(4):692-6.
          pmc: PMC2631744pubmed: 11585534doi: 10.3201/eid0704.010417google scholar: lookup
        5. Autorino GL, Battisti A, Deubel V, Ferrari G, Forletta R, Giovannini A, Lelli R, Murri S, Scicluna MT. West Nile virus epidemic in horses, Tuscany region, Italy.. Emerg Infect Dis 2002 Dec;8(12):1372-8.
          pmc: PMC2738505pubmed: 12498650doi: 10.3201/eid0812.020234google scholar: lookup
        6. Ostlund EN, Crom RL, Pedersen DD, Johnson DJ, Williams WO, Schmitt BJ. Equine West Nile encephalitis, United States.. Emerg Infect Dis 2001 Jul-Aug;7(4):665-9.
          pmc: PMC2631754pubmed: 11589171doi: 10.3201/eid0704.010412google scholar: lookup
        7. Porter MB, Long MT, Getman LM, Giguère S, MacKay RJ, Lester GD, Alleman AR, Wamsley HL, Franklin RP, Jacks S, Buergelt CD, Detrisac CJ. West Nile virus encephalomyelitis in horses: 46 cases (2001).. J Am Vet Med Assoc 2003 May 1;222(9):1241-7.
          pubmed: 12725313doi: 10.2460/javma.2003.222.1241google scholar: lookup
        8. Salazar P, Traub-Dargatz JL, Morley PS, Wilmot DD, Steffen DJ, Cunningham WE, Salman MD. Outcome of equids with clinical signs of West Nile virus infection and factors associated with death.. J Am Vet Med Assoc 2004 Jul 15;225(2):267-74.
          pubmed: 15323385doi: 10.2460/javma.2004.225.267google scholar: lookup
        9. USDA: APHIS: VS. West Nile virus in equids in northeastern United States in 2000 [monograph on the Internet] Full report (or highlights). Fort Collins, Colorado: Centers for Epidemiology and Animal Health c2001. [Last accessed 14/5/2007]. Available from: www.aphis.usda.gov/vs/ceah/wnvreport.pdf.
        10. Weese JS, Baird JD, DeLay J, Kenney DG, Staempfli HR, Viel L, Parent J, Smith-Maxie L, Poma R. West Nile virus encephalomyelitis in horses in Ontario: 28 cases.. Can Vet J 2003 Jun;44(6):469-73.
          pmc: PMC340169pubmed: 12839240
        11. Abutarbush SM, O'Connor BP, Clark C, Sampieri F, Naylor JM. Clinical West Nile virus infection in 2 horses in western Canada.. Can Vet J 2004 Apr;45(4):315-7.
          pmc: PMC548617pubmed: 15144104
        12. Curry P. Saskatchewan mosquitoes and West Nile virus. Blue Jay 2004;62:104–111.
        13. Bunning ML, Bowen RA, Cropp CB, Sullivan KG, Davis BS, Komar N, Godsey MS, Baker D, Hettler DL, Holmes DA, Biggerstaff BJ, Mitchell CJ. Experimental infection of horses with West Nile virus.. Emerg Infect Dis 2002 Apr;8(4):380-6.
          pmc: PMC3393377pubmed: 11971771doi: 10.3201/eid0804.010239google scholar: lookup
        14. Ostlund EN, Andresen JE, Andresen M. West Nile encephalitis.. Vet Clin North Am Equine Pract 2000 Dec;16(3):427-41.
          pubmed: 11219341doi: 10.1016/s0749-0739(17)30087-1google scholar: lookup
        15. Canadian Food Inspection Agency (CFIA) CFIA response to central nervous system signs in horses in West Nile virus endemic areas — field and registered establishment investigation [monograph on the Internet]. Ottawa, Ontario. 2005. [Last accessed 14/5/1007]. Available from: http://www.inspection.gc.ca/english/anima/heasan/disemala/wnvvno/horchee.shtml.
        16. Schuler LA, Khaitsa ML, Dyer NW, Stoltenow CL. Evaluation of an outbreak of West Nile virus infection in horses: 569 cases (2002).. J Am Vet Med Assoc 2004 Oct 1;225(7):1084-9.
          pubmed: 15515988doi: 10.2460/javma.2004.225.1084google scholar: lookup
        17. Woody Ornamentals Entomology @ Cornell University [homepage on the Internet] (New York) Growing degree-day tracker: Explanation of growing degree days c2003. [Last accessed 14/5/2007]. Available from: http://www.entomology.cornell.edu/Extension/Woodys/GrowingDegreeDays.html.
        18. Dohoo I, Martin W, Stryhn H. Mixed models for discrete data. .
        19. Corrigan RL. Prediction multi-species evaluation of human risk of West Nile virus infection, Saskatchewan, 2003. .
        20. Brownstein JS, Rosen H, Purdy D, Miller JR, Merlino M, Mostashari F, Fish D. Spatial analysis of West Nile virus: rapid risk assessment of an introduced vector-borne zoonosis.. Vector Borne Zoonotic Dis 2002 Fall;2(3):157-64.
          pubmed: 12737545doi: 10.1089/15303660260613729google scholar: lookup
        21. Folsatd I, Karter AJ. Parasites, bright males, and the immunocompetence handicap. Am Nat 1992;139:603–622.
        22. Saskatchewan Health [homepage on the Internet] Mosquito season and the West Nile virus: Cover up and avoid mosquitoes. c2003. [Last accessed 14/5/2007]. Available from: http://www.health.gov.sk.ca/rr_wnv_info.html.

        Citations

        This article has been cited 14 times.
        1. Hassanien RT, Hussein HA, Abdelmegeed HK, Abdelwahed DA, Khattab OM, Ali MH, Habashi AR, Ibraheem EM, Shahein MA, Abohatab EM. West Nile virus: The current situation in Egypt. Vet World 2023 May;16(5):1154-1160.
          doi: 10.14202/vetworld.2023.1154-1160pubmed: 37576775google scholar: lookup
        2. Ganzenberg S, Sieg M, Ziegler U, Pfeffer M, Vahlenkamp TW, Hörügel U, Groschup MH, Lohmann KL. Seroprevalence and Risk Factors for Equine West Nile Virus Infections in Eastern Germany, 2020. Viruses 2022 May 30;14(6).
          doi: 10.3390/v14061191pubmed: 35746662google scholar: lookup
        3. Selim A, Megahed A, Kandeel S, Alouffi A, Almutairi MM. West Nile virus seroprevalence and associated risk factors among horses in Egypt. Sci Rep 2021 Oct 22;11(1):20932.
          doi: 10.1038/s41598-021-00449-6pubmed: 34686730google scholar: lookup
        4. de Heus P, Kolodziejek J, Hubálek Z, Dimmel K, Racher V, Nowotny N, Cavalleri JV. West Nile Virus and Tick-Borne Encephalitis Virus Are Endemic in Equids in Eastern Austria. Viruses 2021 Sep 19;13(9).
          doi: 10.3390/v13091873pubmed: 34578454google scholar: lookup
        5. Levasseur A, Arsenault J, Paré J. Surveillance of West Nile virus in horses in Canada: A retrospective study of cases reported to the Canadian Food Inspection Agency from 2003 to 2019. Can Vet J 2021 May;62(5):469-476.
          pubmed: 33967285
        6. Bertram FM, Thompson PN, Venter M. Epidemiology and Clinical Presentation of West Nile Virus Infection in Horses in South Africa, 2016-2017. Pathogens 2020 Dec 30;10(1).
          doi: 10.3390/pathogens10010020pubmed: 33396935google scholar: lookup
        7. Bażanów B, Jansen van Vuren P, Szymański P, Stygar D, Frącka A, Twardoń J, Kozdrowski R, Pawęska JT. A Survey on West Nile and Usutu Viruses in Horses and Birds in Poland. Viruses 2018 Feb 17;10(2).
          doi: 10.3390/v10020087pubmed: 29462983google scholar: lookup
        8. Suen WW, Uddin MJ, Wang W, Brown V, Adney DR, Broad N, Prow NA, Bowen RA, Hall RA, Bielefeldt-Ohmann H. Experimental West Nile Virus Infection in Rabbits: An Alternative Model for Studying Induction of Disease and Virus Control. Pathogens 2015 Jul 14;4(3):529-58.
          doi: 10.3390/pathogens4030529pubmed: 26184326google scholar: lookup
        9. Aharonson-Raz K, Lichter-Peled A, Tal S, Gelman B, Cohen D, Klement E, Steinman A. Spatial and temporal distribution of West Nile virus in horses in Israel (1997-2013)--from endemic to epidemics. PLoS One 2014;9(11):e113149.
          doi: 10.1371/journal.pone.0113149pubmed: 25402217google scholar: lookup
        10. Marka A, Diamantidis A, Papa A, Valiakos G, Chaintoutis SC, Doukas D, Tserkezou P, Giannakopoulos A, Papaspyropoulos K, Patsoula E, Badieritakis E, Baka A, Tseroni M, Pervanidou D, Papadopoulos NT, Koliopoulos G, Tontis D, Dovas CI, Billinis C, Tsakris A, Kremastinou J, Hadjichristodoulou C, Vakalis N, Vassalou E, Zarzani S, Zounos A, Komata K, Balatsos G, Beleri S, Mpimpa A, Papavasilopoulos V, Rodis I, Spanakos G, Tegos N, Spyrou V, Dalabiras Z, Birtsas P, Athanasiou L, Papanastassopoulou M, Ioannou C, Athanasiou C, Gerofotis C, Papadopoulou E, Testa T, Tsakalidou O, Rachiotis G, Bitsolas N, Mamouris Z, Moutou K, Sarafidou T, Stamatis K, Sarri K, Tsiodras S, Georgakopoulou T, Detsis M, Mavrouli M, Stavropoulou A, Politi L, Mageira G, Christopoulou V, Diamantopoulou G, Spanakis N, Vrioni G, Piperaki ET, Mitsopoulou K, Kioulos I, Michaelakis A, Stathis I, Tselentis I, Psaroulaki A, Keramarou M, Chochlakis D, Photis Y, Konstantinou M, Manetos P, Tsobanoglou S, Mourelatos S, Antalis V, Pergantas P, Eleftheriou G. West Nile virus state of the art report of MALWEST Project. Int J Environ Res Public Health 2013 Dec 2;10(12):6534-610.
          doi: 10.3390/ijerph10126534pubmed: 24317379google scholar: lookup
        11. Epp TY, Waldner C, Berke O. Predictive risk mapping of West Nile virus (WNV) infection in Saskatchewan horses. Can J Vet Res 2011 Jul;75(3):161-70.
          pubmed: 22210991
        12. Nistor P, Stanga L, Chirila A, Iorgoni V, Gligor A, Ciresan A, Popa I, Florea B, Imre M, Cocioba V, Iancu I, Degi J, Herman V. Seroprevalence and Passive Clinical Surveillance of West Nile Virus in Horses from Ecological High-Risk Areas in Western Romania: Exploratory Findings from a Cross-Sectional Study. Microorganisms 2025 Aug 16;13(8).
          doi: 10.3390/microorganisms13081910pubmed: 40871414google scholar: lookup
        13. Abbas I, Ahmed F, Muqaddas H, Alberti A, Varcasia A, Sedda L. Epidemiology and surveillance of West Nile virus in the Mediterranean Basin during 2010-2023: A systematic review. Curr Res Parasitol Vector Borne Dis 2025;7:100277.
          doi: 10.1016/j.crpvbd.2025.100277pubmed: 40586111google scholar: lookup
        14. Magallanes S, Llorente F, Ruiz-López MJ, Martínez-de la Puente J, Soriguer R, Calderon J, Jímenez-Clavero MÁ, Aguilera-Sepúlveda P, Figuerola J. Long-term serological surveillance for West Nile and Usutu virus in horses in south-West Spain. One Health 2023 Dec;17:100578.
          doi: 10.1016/j.onehlt.2023.100578pubmed: 38024263google scholar: lookup
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