title: 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.
authors.affiliation: University of Pretoria, Pretoria, South Africa. marietjie.venter@up.ac.za
authors.forename: Marietjie
authors.initials: M
authors.lastname: Venter
authors.forename: Stacey
authors.initials: S
authors.lastname: Human
authors.forename: Dewald
authors.initials: D
authors.lastname: Zaayman
authors.forename: Gertruida H
authors.initials: GH
authors.lastname: Gerdes
authors.forename: June
authors.initials: J
authors.lastname: Williams
authors.forename: Johan
authors.initials: J
authors.lastname: Steyl
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Leman
authors.forename: Janusz Tadeusz
authors.initials: JT
authors.lastname: Paweska
authors.forename: Hildegard
authors.initials: H
authors.lastname: Setzkorn
authors.forename: Gavin
authors.initials: G
authors.lastname: Rous
authors.forename: Sue
authors.initials: S
authors.lastname: Murray
authors.forename: Rissa
authors.initials: R
authors.lastname: Parker
authors.forename: Cynthia
authors.initials: C
authors.lastname: Donnellan
authors.forename: Robert
authors.initials: R
authors.lastname: Swanepoel
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001921:Brain / Q000821:virology; D004196:Disease Outbreaks; D006734:Horse Diseases / Q000453:epidemiology / Q000401:mortality* / Q000821:virology*; D006736:Horses; D007075:Immunoglobulin M / Q000097:blood; D010802:Phylogeny; D012367:RNA, Viral / Q000097:blood; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013019:South Africa / Q000453:epidemiology; D014901:West Nile Fever / Q000453:epidemiology / Q000401:mortality / Q000662:veterinary* / Q000821:virology; D014902:West Nile virus / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*
chemical_list: D000914:Antibodies, Viral; D007075:Immunoglobulin M; D012367:RNA, Viral