Emerging infectious diseases2009; 15(6); 877-884; doi: 10.3201/eid1506.081515

Lineage 2 west nile virus as cause of fatal neurologic disease in horses, South Africa.

Abstract: Serologic evidence suggests that West Nile virus (WNV) is widely distributed in horses in southern Africa. However, because few neurologic cases have been reported, endemic lineage 2 strains were postulated to be nonpathogenic in horses. Recent evidence suggests that highly neuroinvasive lineage 2 strains exist in humans and mice. To determine whether neurologic cases are being missed in South Africa, we tested 80 serum or brain specimens from horses with unexplained fever (n = 48) and/or neurologic signs (n = 32) for WNV. From March 2007 through June 2008, using reverse transcription-PCR (RT-PCR) and immunoglobulin (Ig) M ELISA, we found WNV RNA or IgM in 7/32 horses with acute neurologic disease; 5 horses died or were euthanized. In 5/7 horses, no other pathogen was detected. DNA sequencing for all 5 RT-PCR-positive cases showed the virus belonged to lineage 2. WNV lineage 2 may cause neurologic disease in horses in South Africa.
Publication Date: 2009-06-16 PubMed ID: 19523285PubMed Central: PMC2727306DOI: 10.3201/eid1506.081515Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
  • Journal Article
  • Research Support
  • Non-U.S. Gov't


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 discusses the study carried out in South Africa to test the hypothesis that a lineage 2 strain of West Nile Virus (WNV) could be responsible for fatal neurologic diseases in horses. The study uncovered that such strains could indeed pose neurologic threats to horses, challenging previous beliefs that these strains were nonpathogenic to horses.

Introduction and Background

  • The study originates from the serological evidence (based on or involving the examination of blood serum) indicating the widespread distribution of West Nile Virus (WNV) in horses across southern Africa.
  • Linking neurologic cases amongst horses to WNV was previously limited as endemic lineage 2 strains were assumed to be nonpathogenic (not causing disease) in horses.
  • However, recent studies have pointed towards highly neuroinvasive lineage 2 strains having severe effects on humans and mice.

Methodology and Results

  • To explore whether South Africa was missing neurologic cases in horses caused by WNV, researchers conducted tests including reverse transcription-PCR (RT-PCR) and Immunoglobulin (Ig) M ELISA on 80 serum or brain specimens from horses showing unexplained fevers and/or neurologic symptoms.
  • Of the 32 horses with acute neurologic disease, WNV RNA or IgM was found in seven horses; five of these horses either passed away or were euthanized.
  • In five out of seven horses, no other pathogens were detected, hinting that WNV could be the sole cause of their symptoms.

Conclusion and Implication

  • DNA sequencing of the five RT-PCR-positive cases revealed the presence of lineage 2 WNV strains, directly countering the previously held conjecture that they were non-pathogenic for horses.
  • This research advocates that the lineage 2 strain of the West Nile Virus may be causing neurologic diseases that lead to fatality in horses in South Africa.

Cite This Article

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. (2009). Lineage 2 west nile virus as cause of fatal neurologic disease in horses, South Africa. Emerg Infect Dis, 15(6), 877-884. https://doi.org/10.3201/eid1506.081515


ISSN: 1080-6059
NlmUniqueID: 9508155
Country: United States
Language: English
Volume: 15
Issue: 6
Pages: 877-884

Researcher Affiliations

Venter, Marietjie
  • University of Pretoria, Pretoria, South Africa. marietjie.venter@up.ac.za
Human, Stacey
    Zaayman, Dewald
      Gerdes, Gertruida H
        Williams, June
          Steyl, Johan
            Leman, Patricia A
              Paweska, Janusz Tadeusz
                Setzkorn, Hildegard
                  Rous, Gavin
                    Murray, Sue
                      Parker, Rissa
                        Donnellan, Cynthia
                          Swanepoel, Robert

                            MeSH Terms

                            • Animals
                            • Antibodies, Viral / blood
                            • Brain / virology
                            • Disease Outbreaks
                            • Horse Diseases / epidemiology
                            • Horse Diseases / mortality
                            • Horse Diseases / virology
                            • Horses
                            • Immunoglobulin M / blood
                            • Phylogeny
                            • RNA, Viral / blood
                            • Reverse Transcriptase Polymerase Chain Reaction
                            • Sequence Analysis, DNA
                            • South Africa / epidemiology
                            • West Nile Fever / epidemiology
                            • West Nile Fever / mortality
                            • West Nile Fever / veterinary
                            • West Nile Fever / virology
                            • West Nile virus / classification
                            • West Nile virus / genetics
                            • West Nile virus / immunology
                            • West Nile virus / pathogenicity


                            This article includes 40 references
                            1. Hayes EB, Sejvar JJ, Zaki SR, Lanciotti RS, Bode AV, Campbell GL. Virology, pathology, and clinical manifestations of West Nile virus disease.. Emerg Infect Dis 2005 Aug;11(8):1174-9.
                              pmc: PMC3320472pubmed: 16102303doi: 10.3201/eid1108.050289bgoogle scholar: lookup
                            2. 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.
                              pmc: PMC2732512pubmed: 12141968doi: 10.3201/eid0808.020027google scholar: lookup
                            3. 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
                            4. Lvov DK, Butenko AM, Gromashevsky VL, Kovtunov AI, Prilipov AG, Kinney R, Aristova VA, Dzharkenov AF, Samokhvalov EI, Savage HM, Shchelkanov MY, Galkina IV, Deryabin PG, Gubler DJ, Kulikova LN, Alkhovsky SK, Moskvina TM, Zlobina LV, Sadykova GK, Shatalov AG, Lvov DN, Usachev VE, Voronina AG. West Nile virus and other zoonotic viruses in Russia: examples of emerging-reemerging situations.. Arch Virol Suppl 2004;(18):85-96.
                              pubmed: 15119764doi: 10.1007/978-3-7091-0572-6_7google scholar: lookup
                            5. Bakonyi T, Hubu00e1lek 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.
                              pmc: PMC3320449pubmed: 15752439doi: 10.3201/eid1102.041028google scholar: lookup
                            6. Bondre VP, Jadi RS, Mishra AC, Yergolkar PN, Arankalle VA. West Nile virus isolates from India: evidence for a distinct genetic lineage.. J Gen Virol 2007 Mar;88(Pt 3):875-884.
                              doi: 10.1099/vir.0.82403-0pubmed: 17325360google scholar: lookup
                            7. Campbell GL, Marfin AA, Lanciotti RS, Gubler DJ. West Nile virus.. Lancet Infect Dis 2002 Sep;2(9):519-29.
                              doi: 10.1016/S1473-3099(02)00368-7pubmed: 12206968google scholar: lookup
                            8. Petersen LR, Marfin AA. West Nile virus: a primer for the clinician.. Ann Intern Med 2002 Aug 6;137(3):173-9.
                            9. Ward MP, Levy M, Thacker HL, Ash M, Norman SK, Moore GE, Webb PW. Investigation of an outbreak of encephalomyelitis caused by West Nile virus in 136 horses.. J Am Vet Med Assoc 2004 Jul 1;225(1):84-9.
                              doi: 10.2460/javma.2004.225.84pubmed: 15239478google scholar: lookup
                            10. 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.
                              doi: 10.2460/javma.2004.225.1084pubmed: 15515988google scholar: lookup
                            11. Dauphin G, Zientara S, Zeller H, Murgue B. West Nile: worldwide current situation in animals and humans.. Comp Immunol Microbiol Infect Dis 2004 Sep;27(5):343-55.
                              doi: 10.1016/j.cimid.2004.03.009pubmed: 15225984google scholar: lookup
                            12. Nielsen CF, Reisen WK, Armijos MV, Maclachlan NJ, Scott TW. High subclinical West Nile virus incidence among nonvaccinated horses in northern California associated with low vector abundance and infection.. Am J Trop Med Hyg 2008 Jan;78(1):45-52.
                              pubmed: 18187784
                            13. 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
                            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. Dauphin G, Zientara S. West Nile virus: recent trends in diagnosis and vaccine development.. Vaccine 2007 Jul 26;25(30):5563-76.
                              doi: 10.1016/j.vaccine.2006.12.005pubmed: 17292514google scholar: lookup
                            16. Beasley DW. Recent advances in the molecular biology of west nile virus.. Curr Mol Med 2005 Dec;5(8):835-50.
                              doi: 10.2174/156652405774962272pubmed: 16375717google scholar: lookup
                            17. 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.
                            18. 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/eid1401.070457pmc: PMC2600181pubmed: 18258114google scholar: lookup
                            19. Bakonyi T, Ivanics E, Erdu00e9lyi K, Ursu K, Ferenczi E, Weissenbu00f6ck H, Nowotny N. Lineage 1 and 2 strains of encephalitic West Nile virus, central Europe.. Emerg Infect Dis 2006 Apr;12(4):618-23.
                              pmc: PMC3294705pubmed: 16704810doi: 10.3201/eid1204.051379google scholar: lookup
                            20. 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
                            21. 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
                            22. Beasley DW, Davis CT, Whiteman M, Granwehr B, Kinney RM, Barrett AD. Molecular determinants of virulence of West Nile virus in North America.. Arch Virol Suppl 2004;(18):35-41.
                              pubmed: 15119761doi: 10.1007/978-3-7091-0572-6_4google scholar: lookup
                            23. 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.
                            24. Berthet FX, Zeller HG, Drouet MT, Rauzier J, Digoutte JP, Deubel V. Extensive nucleotide changes and deletions within the envelope glycoprotein gene of Euro-African West Nile viruses.. J Gen Virol 1997 Sep;78 ( Pt 9):2293-7.
                              pubmed: 9292017doi: 10.1099/0022-1317-78-9-2293google scholar: lookup
                            25. Guindon S, Gascuel O. A simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood.. Syst Biol 2003 Oct;52(5):696-704.
                              doi: 10.1080/10635150390235520pubmed: 14530136google scholar: lookup
                            26. Tamura K, Dudley J, Nei M, Kumar S. MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software version 4.0.. Mol Biol Evol 2007 Aug;24(8):1596-9.
                              doi: 10.1093/molbev/msm092pubmed: 17488738google scholar: lookup
                            27. Swanepoel R, Struthers JK, Erasmus MJ, Shepherd SP, McGillivray GM, Erasmus BJ, Barnard BJ. Comparison of techniques for demonstrating antibodies to Rift Valley fever virus.. J Hyg (Lond) 1986 Oct;97(2):317-29.
                              pmc: PMC2083537pubmed: 3537118doi: 10.1017/s0022172400065414google scholar: lookup
                            28. Paweska JT, Burt FJ, Swanepoel R. Validation of IgG-sandwich and IgM-capture ELISA for the detection of antibody to Rift Valley fever virus in humans.. J Virol Methods 2005 Mar;124(1-2):173-81.
                            29. Paweska JT, Burt FJ, Anthony F, Smith SJ, Grobbelaar AA, Croft JE, Ksiazek TG, Swanepoel R. IgG-sandwich and IgM-capture enzyme-linked immunosorbent assay for the detection of antibody to Rift Valley fever virus in domestic ruminants.. J Virol Methods 2003 Nov;113(2):103-12.
                              doi: 10.1016/S0166-0934(03)00228-3pubmed: 14553896google scholar: lookup
                            30. Niedrig M, Sonnenberg K, Steinhagen K, Paweska JT. Comparison of ELISA and immunoassays for measurement of IgG and IgM antibody to West Nile virus in human sera against virus neutralisation.. J Virol Methods 2007 Jan;139(1):103-5.
                            31. House C, Mikiciuk PE, Berninger ML. Laboratory diagnosis of African horse sickness: comparison of serological techniques and evaluation of storage methods of samples for virus isolation.. J Vet Diagn Invest 1990 Jan;2(1):44-50.
                              pubmed: 2128615doi: 10.1177/104063879000200108google scholar: lookup
                            32. Bremer CW, Viljoen GJ. Detection of African horsesickness virus and discrimination between two equine orbivirus serogroups by reverse transcription polymerase chain reaction.. Onderstepoort J Vet Res 1998 Mar;65(1):1-8.
                              pubmed: 9629584
                            33. GOLDWASSER RA, KISSLING RE. Fluorescent antibody staining of street and fixed rabies virus antigens.. Proc Soc Exp Biol Med 1958 Jun;98(2):219-23.
                              pubmed: 13554598doi: 10.3181/00379727-98-23996google scholar: lookup
                            34. Haines DM, Chelack BJ. Technical considerations for developing enzyme immunohistochemical staining procedures on formalin-fixed paraffin-embedded tissues for diagnostic pathology.. J Vet Diagn Invest 1991 Jan;3(1):101-12.
                              pubmed: 2039784doi: 10.1177/104063879100300128google scholar: lookup
                            35. Ward MP, Scheurmann JA. The relationship between equine and human West Nile virus disease occurrence.. Vet Microbiol 2008 Jun 22;129(3-4):378-83.
                              doi: 10.1016/j.vetmic.2007.11.022pubmed: 18182255google scholar: lookup
                            36. Quan M, van Vuuren M, Howell PG, Groenewald D, Guthrie AJ. Molecular epidemiology of the African horse sickness virus S10 gene.. J Gen Virol 2008 May;89(Pt 5):1159-1168.
                              doi: 10.1099/vir.0.83502-0pubmed: 18420793google scholar: lookup
                            37. Mellor PS, Hamblin C. African horse sickness.. Vet Res 2004 Jul-Aug;35(4):445-66.
                              doi: 10.1051/vetres:2004021pubmed: 15236676google scholar: lookup
                            38. von Teichman BF, Smit TK. Evaluation of the pathogenicity of African Horsesickness (AHS) isolates in vaccinated animals.. Vaccine 2008 Sep 15;26(39):5014-21.
                              doi: 10.1016/j.vaccine.2008.07.037pubmed: 18682269google scholar: lookup
                            39. Erasmus BJ, Adelaar TF, Smit JD, Lecatsas G, Toms T. The isolation and characterization of equine encephalosis virus. Bull Off Int Epizoot. 1970;74:781u20139.
                            40. Meiswinkel R. The 1996 outbreak of African horse sickness in South Africa--the entomological perspective.. Arch Virol Suppl 1998;14:69-83.
                              pubmed: 9785497doi: 10.1007/978-3-7091-6823-3_8google scholar: lookup


                            This article has been cited 39 times.
                            1. Fehu00e9r OE, Fehu00e9rvu00e1ri P, Tolnai CH, Forgu00e1ch P, Malik P, Jerzsele u00c1, 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).
                              doi: 10.3390/v14112551pubmed: 36423160google scholar: lookup
                            2. Cavalleri JV, Korbacska-Kutasi O, Leblond A, Paillot R, Pusterla N, Steinmann E, Tomlinson J. European College of Equine Internal Medicine consensus statement on equine flaviviridae infections in Europe.. J Vet Intern Med 2022 Nov;36(6):1858-1871.
                              doi: 10.1111/jvim.16581pubmed: 36367340google scholar: lookup
                            3. Mencattelli G, Ndione MHD, Rosu00e0 R, Marini G, Diagne CT, Diagne MM, Fall G, Faye O, Diallo M, Faye O, Savini G, Rizzoli A. Epidemiology of West Nile virus in Africa: An underestimated threat.. PLoS Negl Trop Dis 2022 Jan;16(1):e0010075.
                              doi: 10.1371/journal.pntd.0010075pubmed: 35007285google scholar: lookup
                            4. Saiz JC, Martu00edn-Acebes MA, Blu00e1zquez AB, Escribano-Romero E, Poderoso T, Jimu00e9nez de Oya N. Pathogenicity and virulence of West Nile virus revisited eight decades after its first isolation.. Virulence 2021 Dec;12(1):1145-1173.
                              doi: 10.1080/21505594.2021.1908740pubmed: 33843445google scholar: lookup
                            5. Guggemos HD, Fendt M, Hieke C, Heyde V, Mfune JKE, Borgemeister C, Junglen S. Simultaneous circulation of two West Nile virus lineage 2 clades and Bagaza virus in the Zambezi region, Namibia.. PLoS Negl Trop Dis 2021 Apr;15(4):e0009311.
                              doi: 10.1371/journal.pntd.0009311pubmed: 33798192google scholar: lookup
                            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. Ain-Najwa MY, Yasmin AR, Arshad SS, Omar AR, Abu J, Kumar K, Mohammed HO, Natasha JA, Mohammed MN, Bande F, Abdullah ML, J Rovie-Ryan J. Exposure to Zoonotic West Nile Virus in Long-Tailed Macaques and Bats in Peninsular Malaysia.. Animals (Basel) 2020 Dec 10;10(12).
                              doi: 10.3390/ani10122367pubmed: 33321964google scholar: lookup
                            8. Bakhshi H, Mousson L, Vazeille M, Zakeri S, Raz A, de Lamballerie X, Dinparast-Djadid N, Failloux AB. High Transmission Potential of West Nile Virus Lineage 1 for Cx. pipiens s.l. of Iran.. Viruses 2020 Apr 3;12(4).
                              doi: 10.3390/v12040397pubmed: 32260215google scholar: lookup
                            9. Ko HY, Li YT, Chao DY, Chang YC, Li ZT, Wang M, Kao CL, Wen TH, Shu PY, Chang GJ, King CC. Inter- and intra-host sequence diversity reveal the emergence of viral variants during an overwintering epidemic caused by dengue virus serotype 2 in southern Taiwan.. PLoS Negl Trop Dis 2018 Oct;12(10):e0006827.
                              doi: 10.1371/journal.pntd.0006827pubmed: 30286095google scholar: lookup
                            10. Sule WF, Oluwayelu DO, Hernu00e1ndez-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-ypubmed: 30005653google scholar: lookup
                            11. Romo H, Papa A, Kading R, Clark R, Delorey M, Brault AC. Comparative Vector Competence of North American Culex pipiens and Culex quinquefasciatus for African and European Lineage 2 West Nile Viruses.. Am J Trop Med Hyg 2018 Jun;98(6):1863-1869.
                              doi: 10.4269/ajtmh.17-0935pubmed: 29637885google scholar: lookup
                            12. Bau017canu00f3w B, Jansen van Vuren P, Szymau0144ski P, Stygar D, Fru0105cka A, Twardou0144 J, Kozdrowski R, Pawu0119ska 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
                            13. Braack L, Gouveia de Almeida AP, Cornel AJ, Swanepoel R, de Jager C. Mosquito-borne arboviruses of African origin: review of key viruses and vectors.. Parasit Vectors 2018 Jan 9;11(1):29.
                              doi: 10.1186/s13071-017-2559-9pubmed: 29316963google scholar: lookup
                            14. 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/eid2312.162078pubmed: 29148375google scholar: lookup
                            15. Tantely ML, Goodman SM, Rakotondranaivo T, Boyer S. Review of West Nile virus circulation and outbreak risk in Madagascar: Entomological and ornithological perspectives.. Parasite 2016;23:49.
                              doi: 10.1051/parasite/2016058pubmed: 27849515google scholar: lookup
                            16. Mentoor JL, Lubisi AB, Gerdes T, Human S, Williams JH, Venter M. Full-Genome Sequence of a Neuroinvasive West Nile Virus Lineage 2 Strain from a Fatal Horse Infection in South Africa.. Genome Announc 2016 Jul 28;4(4).
                              doi: 10.1128/genomeA.00740-16pubmed: 27469963google scholar: lookup
                            17. 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/eid2112.150132pubmed: 26583836google scholar: lookup
                            18. 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
                            19. Chaintoutis SC, Diakakis N, Papanastassopoulou M, Banos G, Dovas CI. Evaluation of Cross-Protection of a Lineage 1 West Nile Virus Inactivated Vaccine against Natural Infections from a Virulent Lineage 2 Strain in Horses, under Field Conditions.. Clin Vaccine Immunol 2015 Sep;22(9):1040-9.
                              doi: 10.1128/CVI.00302-15pubmed: 26178384google scholar: lookup
                            20. Chancey C, Grinev A, Volkova E, Rios M. The global ecology and epidemiology of West Nile virus.. Biomed Res Int 2015;2015:376230.
                              doi: 10.1155/2015/376230pubmed: 25866777google scholar: lookup
                            21. Hernu00e1ndez-Triana LM, Jeffries CL, Mansfield KL, Carnell G, Fooks AR, Johnson N. Emergence of west nile virus lineage 2 in europe: a review on the introduction and spread of a mosquito-borne disease.. Front Public Health 2014;2:271.
                              doi: 10.3389/fpubh.2014.00271pubmed: 25538937google scholar: lookup
                            22. Lwande OW, Venter M, Lutomiah J, Michuki G, Rumberia C, Gakuya F, Obanda V, Tigoi C, Odhiambo C, Nindo F, Symekher S, Sang R. Whole genome phylogenetic investigation of a West Nile virus strain isolated from a tick sampled from livestock in north eastern Kenya.. Parasit Vectors 2014 Nov 28;7:542.
                              doi: 10.1186/s13071-014-0542-2pubmed: 25430727google scholar: lookup
                            23. Zohaib A, Saqib M, Beck C, Hussain MH, Lowenski S, Lecollinet S, Sial A, Asi MN, Mansoor MK, Saqalein M, Sajid MS, Ashfaq K, Muhammad G, Cao S. High prevalence of West Nile virus in equines from the two provinces of Pakistan.. Epidemiol Infect 2015 Jul;143(9):1931-5.
                              doi: 10.1017/S0950268814002878pubmed: 25358382google 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: 10.1155/2014/907852pubmed: 25302311google scholar: lookup
                            25. Hoover LI, Fredericksen BL. IFN-dependent and -independent reduction in West Nile virus infectivity in human dermal fibroblasts.. Viruses 2014 Mar 24;6(3):1424-41.
                              doi: 10.3390/v6031424pubmed: 24662674google scholar: lookup
                            26. 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
                            27. Donadieu E, Bahuon C, Lowenski S, Zientara S, Coulpier M, Lecollinet S. Differential virulence and pathogenesis of West Nile viruses.. Viruses 2013 Nov 22;5(11):2856-80.
                              doi: 10.3390/v5112856pubmed: 24284878google scholar: lookup
                            28. Pauli G, Bauerfeind U, Blu00fcmel J, Burger R, Drosten C, Gru00f6ner A, Gu00fcrtler L, Heiden M, Hildebrandt M, Jansen B, Montag-Lessing T, Offergeld R, Seitz R, Schlenkrich U, Schottstedt V, Strobel J, Willkommen H. West nile virus.. Transfus Med Hemother 2013 Aug;40(4):265-84.
                              doi: 10.1159/000353698pubmed: 24179475google scholar: lookup
                            29. Angenvoort J, Brault AC, Bowen RA, Groschup MH. West Nile viral infection of equids.. Vet Microbiol 2013 Nov 29;167(1-2):168-80.
                              doi: 10.1016/j.vetmic.2013.08.013pubmed: 24035480google scholar: lookup
                            30. Iyer AV, Kousoulas KG. A review of vaccine approaches for West Nile virus.. Int J Environ Res Public Health 2013 Sep 10;10(9):4200-23.
                              doi: 10.3390/ijerph10094200pubmed: 24025396google scholar: lookup
                            31. Hubu00e1lek Z, Ludvu00edkovu00e1 E, Jahn P, Treml F, Rudolf I, Svobodovu00e1 P, u0160ikutovu00e1 S, Betu00e1u0161ovu00e1 L, Bu00edreu0161 J, Moju017eu00edu0161 M, Tinu00e1k M, Boldiu017eu00e1r M, Citsou0148ovu00e1 G, Stau0161u0161u00edkovu00e1 Z. West Nile Virus equine serosurvey in the Czech and Slovak republics.. Vector Borne Zoonotic Dis 2013 Oct;13(10):733-8.
                              doi: 10.1089/vbz.2012.1159pubmed: 23919605google scholar: lookup
                            32. Scherbik SV, Pulit-Penaloza JA, Basu M, Courtney SC, Brinton MA. Increased early RNA replication by chimeric West Nile virus W956IC leads to IPS-1-mediated activation of NF-u03baB and insufficient virus-mediated counteraction of the resulting canonical type I interferon signaling.. J Virol 2013 Jul;87(14):7952-65.
                              doi: 10.1128/JVI.02842-12pubmed: 23678179google scholar: lookup
                            33. Patel P, Landt O, Kaiser M, Faye O, Koppe T, Lass U, Sall AA, Niedrig M. Development of one-step quantitative reverse transcription PCR for the rapid detection of flaviviruses.. Virol J 2013 Feb 14;10:58.
                              doi: 10.1186/1743-422X-10-58pubmed: 23410000google scholar: lookup
                            34. van Eeden C, Williams JH, Gerdes TG, van Wilpe E, Viljoen A, Swanepoel R, Venter M. Shuni virus as cause of neurologic disease in horses.. Emerg Infect Dis 2012 Feb;18(2):318-21.
                              doi: 10.3201/eid1802.111403pubmed: 22305525google scholar: lookup
                            35. Pesko KN, Ebel GD. West Nile virus population genetics and evolution.. Infect Genet Evol 2012 Mar;12(2):181-90.
                              doi: 10.1016/j.meegid.2011.11.014pubmed: 22226703google scholar: lookup
                            36. 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/eid1708.101794pubmed: 21801644google scholar: lookup
                            37. Calistri P, Giovannini A, Hubalek Z, Ionescu A, Monaco F, Savini G, Lelli R. Epidemiology of west nile in europe and in the mediterranean basin.. Open Virol J 2010 Apr 22;4:29-37.
                              doi: 10.2174/1874357901004020029pubmed: 20517490google scholar: lookup
                            38. Pfeffer M, Dobler G. Emergence of zoonotic arboviruses by animal trade and migration.. Parasit Vectors 2010 Apr 8;3(1):35.
                              doi: 10.1186/1756-3305-3-35pubmed: 20377873google scholar: lookup
                            39. Venter M, Steyl J, Human S, Weyer J, Zaayman D, Blumberg L, Leman PA, Paweska J, Swanepoel R. Transmission of West Nile virus during horse autopsy.. Emerg Infect Dis 2010 Mar;16(3):573-5.
                              doi: 10.3201/eid1603.091042pubmed: 20202454google scholar: lookup