title: Solitary IgM phase II response has a limited predictive value in the diagnosis of acute Q fever.
abstract: We investigated the positive predictive value (PPV) of a solitary positive immunoglobulin M (IgM) phase II response for the serodiagnosis of acute Q fever detected with either an indirect immunofluorescence assay (IFA) or an enzyme-linked immunosorbent assay (ELISA). Initial and follow-up sera from patients suspected of acute Q fever were included if initially only IgM phase II tested positive with IFA in 2008 (n=92), or ELISA in 2009 (n=85). A seroconversion for Q fever was defined as an initial sample being IgG phase II negative but positive in the follow-up sample. The PPV of an initial isolated IgM phase II result detected by IFA or ELISA was 65% and 51%, respectively, and therefore appeared not to adequately predict acute Q fever. For this reason it cannot be used as a diagnostic criterion nor should it be included in public health notification without confirmation with other markers or a follow-up serum sample.
authors.affiliation: Academic Collaborative Centre for Public Health AMPHI, Radboud University Nijmegen Medical Centre, GeertGrooteplein Noord 21, Nijmegen, The Netherlands. S.Raven@elg.umcn.nl
authors.forename: C F H
authors.initials: CF
authors.lastname: Raven
authors.forename: J L A
authors.initials: JL
authors.lastname: Hautvast
authors.forename: T
authors.initials: T
authors.lastname: Herremans
authors.forename: A C A P
authors.initials: AC
authors.lastname: Leenders
authors.forename: P M
authors.initials: PM
authors.lastname: Schneeberger
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002648:Child; D016997:Coxiella burnetii / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005500:Follow-Up Studies; D006801:Humans; D007110:Immunity, Active; D007075:Immunoglobulin M / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011778:Q Fever / Q000175:diagnosis* / Q000276:immunology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D015415:Biomarkers; D007075:Immunoglobulin M