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Test ID: SFLB    
Influenza Virus B Antibodies, IgG and IgM (Separate Determinations), Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis of recent infection when isolation of the organism by culture is unsuccessful

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Influenza is usually a mild illness of the upper respiratory tract. Involvement of the lower respiratory tract, however, can lead to 4 types of clinical syndromes; physical signs of lower respiratory tract involvement without roentgenographic evidence of pneumonia, influenza complicated by bacterial pneumonia, primary influenza virus pneumonia, and combined influenzal and bacterial pneumonias.

 

Influenza virus infections are most severe in patients with certain preexisting conditions such as rheumatic heart disease, bronchopulmonary disease, impaired renal function, and diabetes mellitus. Infections can be more severe in elderly patients, pregnant females, and immunocompromised patients.

 

Influenza virus type B generally produces less severe disease than type A. Outbreaks of influenza type B virus are usually more localized than type A. Both infections occur in the United States between November and March.

 

Influenza A is susceptible to antiviral activity of amantadine while influenza B is not inhibited by this drug.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

IgG: <1:10

IgM: <1:10

Interpretation Provides information to assist in interpretation of the test results

The presence of IgM class antibody or a 4-fold or greater rise in titer in paired (acute and convalescent) sera indicates recent infection.

 

The presence of IgG class antibody alone generally indicates past exposure.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Influenza virus infections occur exclusively from November through March.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Rothbarth PH, Groen J, Bohnen AM, et al: Influenza virus serology-a comparative study. J Virol Methods 1999;78:163-169

2. Pachucki CT: The diagnosis of influenza. Semin Resp Infect 1992;7:46-53

3. Wendt CH: Community respiratory viruses: organ transplant recipients. Am J Med 1997;102:31-36:42-43