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Pathogens (Basel, Switzerland)2020; 10(1); 20; doi: 10.3390/pathogens10010020

Epidemiology and Clinical Presentation of West Nile Virus Infection in Horses in South Africa, 2016-2017.

Abstract: Although West Nile virus (WNV) is endemic to South Africa (RSA), it has only become recognized as a significant cause of neurological disease in humans and horses locally in the past 2 decades, as it emerged globally. This article describes the epidemiological and clinical presentation of WNV in horses across RSA during 2016-2017. In total, 54 WNV-positive cases were identified by passive surveillance in horses with febrile and/or neurological signs at the Centre for Viral Zoonoses, University of Pretoria. They were followed up and compared to 120 randomly selected WNV-negative controls with the same case definition and during the same time period. Of the WNV-positive cases, 52% had fever, 92% displayed neurological signs, and 39% experienced mortality. Cases occurred mostly in WNV-unvaccinated horses <5 years old, during late summer and autumn after heavy rain, in the temperate to warm eastern parts of RSA. WNV-positive cases that had only neurological signs without fever were more likely to die. In the multivariable analysis, the odds of WNV infection were associated with season (late summer), higher altitude, more highly purebred animals, younger age, and failure to vaccinate against WNV. Vaccination is currently the most effective prophylactic measure to reduce WNV morbidity and mortality in horses.
Publication Date: 2020-12-30 PubMed ID: 33396935PubMed Central: PMC7823741DOI: 10.3390/pathogens10010020Google Scholar: Lookup
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  • Journal Article

Summary

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The study examines the widespread presence and impact of West Nile virus (WNV) in horses across South Africa, taking into consideration aspects such as seasonality, equine age, breed, and the role of vaccination in mitigating WNV cases.

Overview of Methodology and Findings

  • The research was carried out in South Africa during the period of 2016-2017, focusing on horses that presented febrile and/or neurological symptoms — indicators of potential WNV infection.
  • Passive surveillance at the Centre for Viral Zoonoses, University of Pretoria helped in identifying 54 WNV-positive cases which then formed the basis of the research. These cases were compared with 120 randomly chosen WNV-negative control horses.
  • The study reported that out of all the WNV-positive cases, 52% presented with fever, 92% exhibited neurological symptoms, and there was a mortality rate of 39%.

Key Factors in WNV Infection

  • The research identified several factors that made the horses more susceptible to WNV. They included the animals being largely unvaccinated, less than 5 years old, the time of year being late summer or autumn following heavy rain, and geographic location — primarily the eastern parts of South Africa which have a temperate to warm climate.
  • Furthermore, it was observed that horses which displayed solely neurological symptoms (without fever) were more likely to succumb to the disease.

Association and Prevention

  • In a multivariable analysis, the odds of WNV infection were found to be associated with season (late summer), higher altitude, more highly purebred animals, younger age, and failure to vaccinate against WNV.
  • The study concludes by emphasizing the important role of vaccination as the most effective preventive measure to reduce both the cases, and the severity of WNV infection in horses.

Cite This Article

APA
Bertram FM, Thompson PN, Venter M. (2020). Epidemiology and Clinical Presentation of West Nile Virus Infection in Horses in South Africa, 2016-2017. Pathogens, 10(1), 20. https://doi.org/10.3390/pathogens10010020

Publication

ISSN: 2076-0817
NlmUniqueID: 101596317
Country: Switzerland
Language: English
Volume: 10
Issue: 1
PII: 20

Researcher Affiliations

Bertram, Freude-Marié
  • Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria 0110, South Africa.
Thompson, Peter N
  • Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria 0110, South Africa.
Venter, Marietjie
  • Centre for Viral Zoonoses, Department of Medical Virology, Faculty of Health Sciences, University of Pretoria, Pretoria 0001, South Africa.

Grant Funding

  • 81095 / National Research Foundation

Conflict of Interest Statement

The authors declare no conflict of interest.

References

This article includes 62 references
  1. Siger L, Bowen R, Karaca K, Murray M, Jagannatha S, Echols B, Nordgren R, Minke JM. Evaluation of the efficacy provided by a Recombinant Canarypox-Vectored Equine West Nile Virus vaccine against an experimental West Nile Virus intrathecal challenge in horses.. Vet Ther 2006 Fall;7(3):249-56.
    pubmed: 17039448
  2. Venter M, Human S, Zaayman D, Gerdes GH, Williams J, Steyl J, Leman PA, Paweska JT, Setzkorn H, Rous G, Murray S, Parker R, Donnellan C, Swanepoel R. Lineage 2 west nile virus as cause of fatal neurologic disease in horses, South Africa.. Emerg Infect Dis 2009 Jun;15(6):877-84.
    doi: 10.3201/eid1506.081515pmc: PMC2727306pubmed: 19523285google scholar: lookup
  3. Beasley DW, Barrett AD, Tesh RB. Resurgence of West Nile neurologic disease in the United States in 2012: what happened? What needs to be done?. Antiviral Res 2013 Jul;99(1):1-5.
  4. Petersen LR, Roehrig JT. West Nile virus: a reemerging global pathogen.. Emerg Infect Dis 2001 Jul-Aug;7(4):611-4.
    doi: 10.3201/eid0704.017401pmc: PMC2631751pubmed: 11585520google scholar: lookup
  5. Castillo-Olivares J, Wood J. West Nile virus infection of horses.. Vet Res 2004 Jul-Aug;35(4):467-83.
    doi: 10.1051/vetres:2004022pubmed: 15236677google scholar: lookup
  6. OIE. Manual of Diagnostic Tests and Vaccines for Terrestrial Animals: West Nile Fever. .
  7. Petersen LR, Brault AC, Nasci RS. West Nile virus: review of the literature.. JAMA 2013 Jul 17;310(3):308-15.
    doi: 10.1001/jama.2013.8042pmc: PMC4563989pubmed: 23860989google scholar: lookup
  8. Ciota AT. West Nile virus and its vectors.. Curr Opin Insect Sci 2017 Aug;22:28-36.
    doi: 10.1016/j.cois.2017.05.002pubmed: 28805636google scholar: lookup
  9. Roehrig JT. West nile virus in the United States - a historical perspective.. Viruses 2013 Dec 10;5(12):3088-108.
    doi: 10.3390/v5123088pmc: PMC3967162pubmed: 24335779google scholar: lookup
  10. Jupp PG. The ecology of West Nile virus in South Africa and the occurrence of outbreaks in humans.. Ann N Y Acad Sci 2001 Dec;951:143-52.
  11. Burt FJ, Grobbelaar AA, Leman PA, Anthony FS, Gibson GV, Swanepoel R. Phylogenetic relationships of southern African West Nile virus isolates.. Emerg Infect Dis 2002 Aug;8(8):820-6.
    doi: 10.3201/eid0808.020027pmc: PMC2732512pubmed: 12141968google scholar: lookup
  12. Venter M, Pretorius M, Fuller JA, Botha E, Rakgotho M, Stivaktas V, Weyer C, Romito M, Williams J. West Nile Virus Lineage 2 in Horses and Other Animals with Neurologic Disease, South Africa, 2008-2015.. Emerg Infect Dis 2017 Dec;23(12):2060-2064.
    doi: 10.3201/eid2312.162078pmc: PMC5708237pubmed: 29148375google scholar: lookup
  13. AAEP. Core Vaccination Guidelines: West Nile Virus. .
  14. Ward MP, Schuermann JA, Highfield LD, Murray KO. Characteristics of an outbreak of West Nile virus encephalomyelitis in a previously uninfected population of horses.. Vet Microbiol 2006 Dec 20;118(3-4):255-9.
    doi: 10.1016/j.vetmic.2006.07.016pubmed: 16971067google scholar: lookup
  15. Lanciotti RS, Ebel GD, Deubel V, Kerst AJ, Murri S, Meyer R, Bowen M, McKinney N, Morrill WE, Crabtree MB, Kramer LD, Roehrig JT. Complete genome sequences and phylogenetic analysis of West Nile virus strains isolated from the United States, Europe, and the Middle East.. Virology 2002 Jun 20;298(1):96-105.
    doi: 10.1006/viro.2002.1449pubmed: 12093177google scholar: lookup
  16. Charrel RN, Brault AC, Gallian P, Lemasson JJ, Murgue B, Murri S, Pastorino B, Zeller H, de Chesse R, de Micco P, de Lamballerie X. Evolutionary relationship between Old World West Nile virus strains. Evidence for viral gene flow between Africa, the Middle East, and Europe.. Virology 2003 Oct 25;315(2):381-8.
    doi: 10.1016/S0042-6822(03)00536-1pubmed: 14585341google scholar: lookup
  17. Bakonyi T, Hubálek Z, Rudolf I, Nowotny N. Novel flavivirus or new lineage of West Nile virus, central Europe.. Emerg Infect Dis 2005 Feb;11(2):225-31.
    doi: 10.3201/eid1102.041028pmc: PMC3320449pubmed: 15752439google scholar: lookup
  18. Vazquez A, Sanchez-Seco MP, Ruiz S, Molero F, Hernandez L, Moreno J, Magallanes A, Tejedor CG, Tenorio A. Putative new lineage of west nile virus, Spain.. Emerg Infect Dis 2010 Mar;16(3):549-52.
    doi: 10.3201/eid1603.091033pmc: PMC3322021pubmed: 20202444google scholar: lookup
  19. Lanciotti RS, Roehrig JT, Deubel V, Smith J, Parker M, Steele K, Crise B, Volpe KE, Crabtree MB, Scherret JH, Hall RA, MacKenzie JS, Cropp CB, Panigrahy B, Ostlund E, Schmitt B, Malkinson M, Banet C, Weissman J, Komar N, Savage HM, Stone W, McNamara T, Gubler DJ. Origin of the West Nile virus responsible for an outbreak of encephalitis in the northeastern United States.. Science 1999 Dec 17;286(5448):2333-7.
    doi: 10.1126/science.286.5448.2333pubmed: 10600742google scholar: lookup
  20. Rappole JH, Derrickson SR, Hubálek Z. Migratory birds and spread of West Nile virus in the Western Hemisphere.. Emerg Infect Dis 2000 Jul-Aug;6(4):319-28.
    doi: 10.3201/eid0604.000401pmc: PMC2640881pubmed: 10905964google scholar: lookup
  21. Barrett ADT. West Nile in Europe: an increasing public health problem.. J Travel Med 2018 Jan 1;25(1).
    doi: 10.1093/jtm/tay096pubmed: 30289526google scholar: lookup
  22. CDC. West Nile Virus Final Cumulative Maps & Data for 1999–2019 in North America. .
  23. Sambri V, Capobianchi M, Charrel R, Fyodorova M, Gaibani P, Gould E, Niedrig M, Papa A, Pierro A, Rossini G, Varani S, Vocale C, Landini MP. West Nile virus in Europe: emergence, epidemiology, diagnosis, treatment, and prevention.. Clin Microbiol Infect 2013 Aug;19(8):699-704.
    doi: 10.1111/1469-0691.12211pubmed: 23594175google scholar: lookup
  24. Di Sabatino D, Bruno R, Sauro F, Danzetta ML, Cito F, Iannetti S, Narcisi V, De Massis F, Calistri P. Epidemiology of West Nile disease in Europe and in the Mediterranean Basin from 2009 to 2013.. Biomed Res Int 2014;2014:907852.
    doi: 10.1155/2014/907852pmc: PMC4180897pubmed: 25302311google scholar: lookup
  25. ECDC. Surveillance and Disease Data for West Nile Fever. .
  26. Camp JV, Nowotny N. The knowns and unknowns of West Nile virus in Europe: what did we learn from the 2018 outbreak?. Expert Rev Anti Infect Ther 2020 Feb;18(2):145-154.
    doi: 10.1080/14787210.2020.1713751pubmed: 31914833google scholar: lookup
  27. de Heus P, Kolodziejek J, Camp JV, Dimmel K, Bagó Z, Hubálek Z, van den Hoven R, Cavalleri JV, Nowotny N. Emergence of West Nile virus lineage 2 in Europe: Characteristics of the first seven cases of West Nile neuroinvasive disease in horses in Austria.. Transbound Emerg Dis 2020 May;67(3):1189-1197.
    doi: 10.1111/tbed.13452pmc: PMC7317211pubmed: 31840920google scholar: lookup
  28. Steyn J, Botha E, Stivaktas VI, Buss P, Beechler BR, Myburgh JG, Steyl J, Williams J, Venter M. West Nile Virus in Wildlife and Nonequine Domestic Animals, South Africa, 2010-2018.. Emerg Infect Dis 2019 Dec;25(12):2290-2294.
    doi: 10.3201/eid2512.190572pmc: PMC6874268pubmed: 31742510google scholar: lookup
  29. Venter M, Human S, van Niekerk S, Williams J, van Eeden C, Freeman F. Fatal neurologic disease and abortion in mare infected with lineage 1 West Nile virus, South Africa.. Emerg Infect Dis 2011 Aug;17(8):1534-6.
    doi: 10.3201/eid1708.101794pmc: PMC3381566pubmed: 21801644google scholar: lookup
  30. Venter M, Swanepoel R. West Nile virus lineage 2 as a cause of zoonotic neurological disease in humans and horses in southern Africa.. Vector Borne Zoonotic Dis 2010 Oct;10(7):659-64.
    doi: 10.1089/vbz.2009.0230pubmed: 20854018google scholar: lookup
  31. Williams JH, van Niekerk S, Human S, van Wilpe E, Venter M. Pathology of fatal lineage 1 and 2 West Nile virus infections in horses in South Africa.. J S Afr Vet Assoc 2014 Sep 1;85(1):1105.
    doi: 10.4102/jsava.v85i1.1105pubmed: 25686260google scholar: lookup
  32. McIntosh BM, Jupp PG, Dos Santos I, Meenehan GM. Epidemics of West Nile and Sindbis viruses in South Africa with Culex (Culex) univittatus Theobald as vector. S. Afr. J. Sci. 1976;72:295–300.
  33. Sule WF, Oluwayelu DO, Hernández-Triana LM, Fooks AR, Venter M, Johnson N. Epidemiology and ecology of West Nile virus in sub-Saharan Africa.. Parasit Vectors 2018 Jul 13;11(1):414.
    doi: 10.1186/s13071-018-2998-ypmc: PMC6043977pubmed: 30005653google scholar: lookup
  34. Zaayman D, Venter M. West Nile virus neurologic disease in humans, South Africa, September 2008-may 2009.. Emerg Infect Dis 2012 Dec;18(12):2051-4.
    doi: 10.3201/eid1812.111208pmc: PMC3557887pubmed: 23171668google scholar: lookup
  35. Botha EM, Markotter W, Wolfaardt M, Paweska JT, Swanepoel R, Palacios G, Nel LH, Venter M. Genetic determinants of virulence in pathogenic lineage 2 West Nile virus strains.. Emerg Infect Dis 2008 Feb;14(2):222-30.
    doi: 10.3201/eid1402.070457pmc: PMC2600181pubmed: 18258114google scholar: lookup
  36. van Eeden C, Swanepoel R, Venter M. Antibodies against West Nile and Shuni Viruses in Veterinarians, South Africa.. Emerg Infect Dis 2014 Aug;20(8):1409-11.
    doi: 10.3201/eid2008.131724pmc: PMC4111201pubmed: 25062350google scholar: lookup
  37. OIE. WAHIS Interface Zoonotic Diseases in Humans: West Nile Virus in South Africa. .
  38. Jupp PG. Mosquitoes as vectors of human disease in South Africa. S. Afr. Fam. Pract. 2005;47:68–72.
  39. Cornel AJ, Jupp PG, Blackburn NK. Environmental temperature on the vector competence of Culex univittatus (Diptera: Culicidae) for West Nile virus.. J Med Entomol 1993 Mar;30(2):449-56.
    doi: 10.1093/jmedent/30.2.449pubmed: 8459423google scholar: lookup
  40. DeFelice NB, Schneider ZD, Little E, Barker C, Caillouet KA, Campbell SR, Damian D, Irwin P, Jones HMP, Townsend J, Shaman J. Use of temperature to improve West Nile virus forecasts.. PLoS Comput Biol 2018 Mar;14(3):e1006047.
  41. Guthrie AJ, Howell PG, Gardner IA, Swanepoel RE, Nurton JP, Harper CK, Pardini A, Groenewald D, Visage CW, Hedges JF, Balasuriya UB, Cornel AJ, MacLachlan NJ. West Nile virus infection of Thoroughbred horses in South Africa (2000-2001).. Equine Vet J 2003 Sep;35(6):601-5.
    doi: 10.2746/042516403775467180pubmed: 14515962google scholar: lookup
  42. van Niekerk S, Human S, Williams J, van Wilpe E, Pretorius M, Swanepoel R, Venter M. Sindbis and Middelburg Old World Alphaviruses Associated with Neurologic Disease in Horses, South Africa.. Emerg Infect Dis 2015 Dec;21(12):2225-9.
    doi: 10.3201/eid2112.150132pmc: PMC4672445pubmed: 26583836google scholar: lookup
  43. Samuel MA, Diamond MS. Pathogenesis of West Nile Virus infection: a balance between virulence, innate and adaptive immunity, and viral evasion.. J Virol 2006 Oct;80(19):9349-60.
    doi: 10.1128/JVI.01122-06pmc: PMC1617273pubmed: 16973541google scholar: lookup
  44. Cantile C, Di Guardo G, Eleni C, Arispici M. Clinical and neuropathological features of West Nile virus equine encephalomyelitis in Italy.. Equine Vet J 2000 Jan;32(1):31-5.
    doi: 10.2746/042516400777612080pubmed: 10661382google scholar: lookup
  45. Long MT, Ostlund EN, Porter MB, Crom RL. Equine West Nile encephalitis: Epidemiological and clinical review for practitioners. Proceedings of the 48th Annual Convention of the American Association of Equine Practitioners Orlando, FL, USA. 4–8 December 2002; pp. 1–6.
  46. Seino KK, Long MT, Gibbs EP, Bowen RA, Beachboard SE, Humphrey PP, Dixon MA, Bourgeois MA. Comparative efficacies of three commercially available vaccines against West Nile Virus (WNV) in a short-duration challenge trial involving an equine WNV encephalitis model.. Clin Vaccine Immunol 2007 Nov;14(11):1465-71.
    doi: 10.1128/CVI.00249-07pmc: PMC2168174pubmed: 17687109google scholar: lookup
  47. Siger L, Bowen RA, Karaca K, Murray MJ, Gordy PW, Loosmore SM, Audonnet JC, Nordgren RM, Minke JM. Assessment of the efficacy of a single dose of a recombinant vaccine against West Nile virus in response to natural challenge with West Nile virus-infected mosquitoes in horses.. Am J Vet Res 2004 Nov;65(11):1459-62.
    doi: 10.2460/ajvr.2004.65.1459pubmed: 15566080google scholar: lookup
  48. Venter M, van Vuren PJ, Mentoor J, Paweska J, Williams J. Inactivated West Nile Virus (WNV) vaccine, Duvaxyn WNV, protects against a highly neuroinvasive lineage 2 WNV strain in mice.. Vaccine 2013 Aug 20;31(37):3856-62.
    doi: 10.1016/j.vaccine.2013.06.059pubmed: 23820079google scholar: lookup
  49. DeFelice NB, Little E, Campbell SR, Shaman J. Ensemble forecast of human West Nile virus cases and mosquito infection rates.. Nat Commun 2017 Feb 24;8:14592.
    doi: 10.1038/ncomms14592pmc: PMC5333106pubmed: 28233783google scholar: lookup
  50. SAWS. Historical Rain Maps. .
  51. Hayes EB, Komar N, Nasci RS, Montgomery SP, O'Leary DR, Campbell GL. Epidemiology and transmission dynamics of West Nile virus disease.. Emerg Infect Dis 2005 Aug;11(8):1167-73.
    doi: 10.3201/eid1108.050289apmc: PMC3320478pubmed: 16102302google scholar: lookup
  52. Jupp PG, Blackburn NK, Thompson DL, Meenehan GM. Sindbis and West Nile virus infections in the Witwatersrand-Pretoria region.. S Afr Med J 1986 Aug 16;70(4):218-20.
    pubmed: 3016922
  53. SAWS. Weathersmart News February 2018. South African Weather Service; Centurion, Gauteng, South Africa: 2018. p. 29.
  54. Hartley C. Personal Communication: Thoroughbred Stud Farm Survey 2017. The Thoroughbred Breeders’ Association of South Africa; Germiston, South Africa: 2019.
  55. WHO. West Nile Virus Fact Sheet. .
  56. Weese JS. AAEP Infectious Disease Guidelines: West Nile Virus. .
  57. HURLBUT HS, RIZK F, TAYLOR RM, WORK TH. A study of the ecology of West Nile virus in Egypt.. Am J Trop Med Hyg 1956 Jul;5(4):579-620.
    doi: 10.4269/ajtmh.1956.5.579pubmed: 13354882google scholar: lookup
  58. Epp T, Waldner C, West K, Townsend H. Factors associated with West Nile virus disease fatalities in horses.. Can Vet J 2007 Nov;48(11):1137-45.
    pmc: PMC2034420pubmed: 18050794
  59. Venter M, Myers TG, Wilson MA, Kindt TJ, Paweska JT, Burt FJ, Leman PA, Swanepoel R. Gene expression in mice infected with West Nile virus strains of different neurovirulence.. Virology 2005 Nov 10;342(1):119-40.
    doi: 10.1016/j.virol.2005.07.013pubmed: 16125213google scholar: lookup
  60. Petersen LR, Marfin AA. West Nile virus: a primer for the clinician.. Ann Intern Med 2002 Aug 6;137(3):173-9.
  61. Ben-Nathan D. Stress and Virulence: West Nile Virus Encephalitis. Isr. J. Vet. Med. 2013;68:6.
  62. Zaayman D, Human S, Venter M. A highly sensitive method for the detection and genotyping of West Nile virus by real-time PCR.. J Virol Methods 2009 May;157(2):155-60.

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  1. Llorente F. West Nile Virus Infection.. Pathogens 2023 Jan 17;12(2).
    doi: 10.3390/pathogens12020151pubmed: 36839423google scholar: lookup
  2. Azarm A, Nasrabadi M, Shahidi F, Dehghan A, Nikpoor F, Zahraie-Ramazani A, Molaeezadeh SM, Bozorgomid F, Tashakori G, Vatandoost H. Insecticide Resistance in the West Nile Encephalitis, Japanese Encephalitis, Avian Malaria and Lymphatic Elephantiasis Vector, Culex pipiens complex (Diptera: Culicidae) in Iran.. J Arthropod Borne Dis 2021 Dec;15(4):349-357.
    doi: 10.18502/jad.v15i4.10499pubmed: 36644301google scholar: lookup
  3. Fehér OE, Fehérvári P, Tolnai CH, Forgách P, Malik P, Jerzsele Á, Wagenhoffer Z, Szenci O, Korbacska-Kutasi O. Epidemiology and Clinical Manifestation of West Nile Virus Infections of Equines in Hungary, 2007-2020.. Viruses 2022 Nov 18;14(11).
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  4. Wibmer CK, Mashilo P. Exploiting V-Gene Bias for Rapid, High-Throughput Monoclonal Antibody Isolation from Horses.. Viruses 2022 Sep 30;14(10).
    doi: 10.3390/v14102172pubmed: 36298728google scholar: lookup
  5. Söderlund-Venermo M, Varma A, Guo D, Gladue DP, Poole E, Pujol FH, Pappu H, Romalde JL, Kramer L, Baz M, Venter M, Moore MD, Nevels MM, Ezzikouri S, Vakharia VN, Wilson WC, Malik YS, Shi Z, Abdel-Moneim AS. World Society for Virology first international conference: Tackling global virus epidemics.. Virology 2022 Jan;566:114-121.
    doi: 10.1016/j.virol.2021.11.009pubmed: 34902730google scholar: lookup
  6. Humphreys JM, Pelzel-McCluskey AM, Cohnstaedt LW, McGregor BL, Hanley KA, Hudson AR, Young KI, Peck D, Rodriguez LL, Peters DPC. Integrating Spatiotemporal Epidemiology, Eco-Phylogenetics, and Distributional Ecology to Assess West Nile Disease Risk in Horses.. Viruses 2021 Sep 12;13(9).
    doi: 10.3390/v13091811pubmed: 34578392google scholar: lookup
  7. Knox A, Beddoe T. Isothermal Nucleic Acid Amplification Technologies for the Detection of Equine Viral Pathogens.. Animals (Basel) 2021 Jul 20;11(7).
    doi: 10.3390/ani11072150pubmed: 34359278google scholar: lookup
  8. Molini U, Franzo G, Nel H, Khaiseb S, Ntahonshikira C, Chiwome B, Baines I, Madzingira O, Monaco F, Savini G, D'Alterio N. West Nile Virus Seroprevalence in a Selected Donkey Population of Namibia.. Front Vet Sci 2021;8:681354.
    doi: 10.3389/fvets.2021.681354pubmed: 34222404google scholar: lookup