Lineage 2 west nile virus as cause of fatal neurologic disease in horses, South Africa.
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.
Venter
Marietjie
M
University of Pretoria, Pretoria, South Africa. marietjie.venter@up.ac.za
Human
Stacey
S
Zaayman
Dewald
D
Gerdes
Gertruida H
GH
Williams
June
J
Steyl
Johan
J
Leman
Patricia A
PA
Paweska
Janusz Tadeusz
JT
Setzkorn
Hildegard
H
Rous
Gavin
G
Murray
Sue
S
Parker
Rissa
R
Donnellan
Cynthia
C
Swanepoel
Robert
R
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*
D000914:Antibodies, Viral; D007075:Immunoglobulin M; D012367:RNA, Viral