Q Fever IgG and IgM Antibodies (Sendout)

Reference Values:

Interpretation:

Phase I antibody titers greater than or equal to phase II antibody titers are consistent with chronic infection or convalescent phase Q fever.

Phase II antibody titers greater than or equal to phase I antibody titers are consistent with acute/active infection.

A negative result argues against Coxiella burnetii infection. If early acute Q fever infection is suspected, collect a second specimen 2 to 3 weeks later and retest.

In Q fever sera, it is common to see IgG titers of 1:128 or greater to both phase I and phase II antibody titers. IgG class antibody titers appear very early in the disease, reaching maximum phase II titers by week 8 and persisting at elevated titers for longer than a year. Phase I titers follow the same pattern, although at much lower levels, and may not be initially detected until convalescence.

In Q fever sera, it is common to see IgM titers of 1:64 or greater.

IgM class antibody titers appear very early in the disease, reaching maximum phase II titers by week 3 and declining to very low levels by week 14. Phase I titers follow the same pattern, although at much lower levels, and may not be initially detected until convalescence.

Cautions: Serologic responses are time dependent. Specimens collected too early in the disease may not have detectable antibody levels. A second specimen collected 2 to 3 weeks may be necessary to detect antibody.

Low level positive titers (ie, <1:256) may remain for prolonged periods of time following resolution of disease.

Orderable as reflex from Q Fever Antibody Screen, Reflex to Titer (Sendout) [RQFVRS] only.

Stability: Refrigerated: 7 days; Frozen: 7 days: Ambient: Unacceptable.

Reject Due To: Gross hemolysis, gross lipemia, gross icterus.