title: Impact of the Yosemite hantavirus outbreak on hantavirus antibody testing at a national reference laboratory.
abstract: In conjunction with the 2012 Yosemite hantavirus outbreak, the number of sera our facility tested for hantavirus antibodies increased. We tracked test results and used the data set to determine if a more efficient testing algorithm was possible. Sera were screened using laboratory-developed pan-hantavirus IgG and IgM enzyme immunoassays (EIAs), with an index of >1.10 defined as positive. Sera that were IgM positive by screening (screen IgM(+)) were tested for Sin Nombre virus (SNV)-specific IgM using a laboratory-developed EIA; screen IgM(+) IgG(+) sera were also tested for SNV IgG using a laboratory-developed immunoblot assay. SNV antibody-positive samples were sent to state public health laboratories (PHL) or the CDC for confirmation. Of 3,946 sera tested from July through December 2012, 205 were screen IgM(+) IgG negative (IgG(-)); 7/205 were SNV IgM(+), but only 1/5 sent to PHL/CDC was confirmed as SNV IgM(+). Of 61 screen IgM(+) IgG(+) sera, 16 were SNV antibody positive; 13/16 sera (from 11 patients) went to PHL/CDC, where SNV infection was confirmed for all patients. Of 12 confirmed patients, 7 had been exposed at Yosemite. A modified algorithm defining screen indices of ≥2.00 as positive identified 11/12 confirmed cases while reducing the number of sera requiring SNV-specific antibody testing by 65%; the patient missed was not tested until 3 months after the onset of symptoms. Hantavirus antibody testing at our facility identified 12 SNV-infected patients, including 7 exposed at Yosemite. Some screen IgM(+) IgG(-) SNV IgM(+) results were false positives, emphasizing the value of PHL/CDC confirmatory testing. We identified a modified algorithm requiring analysis of fewer specimens for SNV-specific antibodies without loss of sensitivity.
authors.affiliation: Focus Diagnostics, Inc., Cypress, CA, USA. hprince@focusdx.com
authors.forename: Harry E
authors.initials: HE
authors.lastname: Prince
authors.forename: Jay M
authors.initials: JM
authors.lastname: Lieberman
mesh_terms: D000465:Algorithms; D000914:Antibodies, Viral / Q000097:blood*; D019411:Clinical Laboratory Techniques / Q000379:methods*; D004196:Disease Outbreaks; D018778:Hantavirus Infections / Q000175:diagnosis*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D029261:Sin Nombre virus / Q000276:immunology*; D014481:United States / Q000453:epidemiology; D014730:Veterinary Medicine / Q000379:methods*
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M