Combined determination of Coxiella burnetii-specific immunoglobulin M (IgM) and IgA improves specificity in the diagnosis of acute Q fever.
Immunoglobulin M (IgM) and IgA responses in patients with acute Q fever were compared by enzyme-linked immunosorbent assay. An increase in both IgM and IgA was observed in paired sera from all 19 patients with acute Q fever, and both IgM and IgA levels showed good correlation with complement fixation test titers. Paired sera from 23 patients with infections other than Q fever were also tested. IgM levels were elevated in three of these patients, while IgA levels were elevated in three different patients (87% specificity for either IgM or IgA). As no patients in the disease control group showed elevated levels of both IgM and IgA, definition of a positive result as elevated levels of both IgM and IgA improved specificity to 100% without a decrease in sensitivity. This study indicates that detection of specific IgA is a useful adjunct to that of IgM in the diagnosis of acute Q fever.
Devine
P
P
Clinical Sciences, University of Queensland, Herston, Australia.
Doyle
C
C
Lambkin
G
G
D000907:Antibodies, Bacterial / Q000097:blood*; D000918:Antibody Specificity; D016022:Case-Control Studies; D003168:Complement Fixation Tests; D016997:Coxiella burnetii / Q000276:immunology*; D003951:Diagnostic Errors; D004797:Enzyme-Linked Immunosorbent Assay / Q000706:statistics & numerical data; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D007239:Infections / Q000276:immunology; D011778:Q Fever / Q000175:diagnosis* / Q000276:immunology*; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods / Q000706:statistics & numerical data
D000907:Antibodies, Bacterial; D007070:Immunoglobulin A; D007075:Immunoglobulin M