title: Frequency of missed cases of probable acute West Nile virus (WNV) infection when testing for WNV RNA alone or WNV immunoglobulin M alone.
abstract: To estimate the frequency of missed cases of acute West Nile virus (WNV) infection if only WNV RNA or immunoglobulin M (IgM) testing is requested, we measured IgM in specimens negative for RNA and vice versa. Whereas 6 (5.5%) of 110 RNA-negative sera were IgM positive, only 3 (1.0%) of 299 IgM-negative sera were RNA positive (P < 0.05). Similarly, 11 (7.8%) of 141 RNA-negative cerebrospinal fluid specimens (CSF) were IgM positive, but 0 (0%) of 118 IgM-negative CSF were RNA positive (P < 0.05). WNV infections may be missed if only RNA or IgM testing is requested, with a higher frequency of missed cases if only RNA testing is requested.
authors.affiliation: Focus Diagnostics, Inc., Cypress, CA 90630, USA. hprince@focusdx.com
authors.forename: Harry E
authors.initials: HE
authors.lastname: Prince
authors.forename: Jan
authors.initials: J
authors.lastname: Calma
authors.forename: Tiffany
authors.initials: T
authors.lastname: Pham
authors.forename: Brent L
authors.initials: BL
authors.lastname: Seaton
mesh_terms: D000914:Antibodies, Viral / Q000097:blood* / Q000134:cerebrospinal fluid*; D005188:False Negative Reactions; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood / Q000134:cerebrospinal fluid; D012367:RNA, Viral / Q000097:blood* / Q000134:cerebrospinal fluid*; D014901:West Nile Fever / Q000175:diagnosis*; D014902:West Nile virus / Q000302:isolation & purification*
chemical_list: D000914:Antibodies, Viral; D007075:Immunoglobulin M; D012367:RNA, Viral