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Influenza A/B, NAA

Flu A, Flu B, Influenza A, Influenza B Virus, URI, ILI

Test Codes

EPIC: LAB7165

Department

Microbiology

Instructions

• Positive tests during the non-respiratory season (generally May through October) must be confirmed by a second method. Specimens will be sent to MDHHS for confirmation.
• RVP, Flu, RSV, and Covid swabbing should be performed at the physician office.
• Please see instructions for Nasopharyngeal (NP) Swab Collection.

Specimen Collection Criteria

Collect: Nasopharyngeal (NP) Swab in viral transport medium (UVT, UTM).

• NP swabs should be held in the nasopharynx for 30 seconds and rotated.
• Transport specimen to the Laboratory immediately after collection.

Physician Office/Draw Specimen Preparation

Arrange for transport to the Laboratory immediately. Maintain NP Swab in viral transport medium (UVT, UTM) refrigerated (2-8°C or 36-46°F) for transport.

Preparation for Courier Transport

Transport: NP Swab in viral transport medium (UVT, UTM) refrigerated (2-8°C or 36-46°F).

Rejection Criteria

• Bloody specimens.
• Specimens submitted on dry swabs.
• Specimens submitted on cotton or calcium alginate swabs, or on wooden shaft swabs.
• Contaminated media (e.g. yellow in color or contain black particles).

Inpatient Specimen Preparation

Transport specimens to the Laboratory immediately after collection.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 8 Hours
Refrigerated (2-8°C or 36-46°F): 7 Days
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Dearborn Microbiology Laboratory
Farmington Hills Microbiology Laboratory
Grosse Pointe Microbiology Laboratory
Lenox Main Laboratory
Livonia Main Laboratory
Royal Oak Clinical Microbiology Laboratory
Taylor Microbiology Laboratory
Trenton Microbiology Laboratory
Troy Microbiology Laboratory
Wayne Microbiology Laboratory

Performed

Sunday – Saturday, 24 hours a day.
Batch tested once per day.
Routine results available within 24-48 hours.

Reference Range

Negative.

Test Methodology

Nucleic Acid Amplification (FDA Approved).

Interpretation

This assay determines the presence of influenza A and influenza B in a respiratory specimen. Nucleic acid amplification testing is the optimal diagnostic modality for detection of respiratory viruses. The sensitivity of this test is greater than 97% as compared to culture.

Clinical Disease

• Influenza moves rapidly throughout the population each winter, causing more than 20,000 excess deaths, principally in the elderly, the immunocompromised, and in patients with chronic lung or kidney conditions (1). In these populations, influenza can also cause polyneuritis, encephalopathy, and inflammation of cardiac and skeletal muscles. Reye's syndrome may also occur after influenza infections.
• Influenza virus causes acute respiratory tract disease characterized by an abrupt onset of fever, chills, headache, and myalgia. Coryza, sore throat, and cough are typical of the disease and these symptoms are often severe and prolonged. In healthy adults, the disease is usually self-limiting and typically resolves within a week. 

Epidemiology

Influenza generally spreads through a population in an epidemic fashion and at least 10 global pandemics have occurred during the past 200 years. Most cases of influenza occur in the winter and early spring (January through April) with peak incidence in January and February. Influenza A causes major epidemics at 2-3 year intervals (1).

Incubation Period

The incubation period is 18-70 hours. Patients are infectious one day before the onset of symptoms and for 3-4 days thereafter. Infants may shed virus for longer periods of time (1).

Transmission

These viruses are very contagious and are transmitted through inhalation of virus-laden aerosols or by autoinoculation after handling fomites contaminated with nasal or throat secretions (1).

Reference

1. Mufson, M.A., 2000. Respiratory Viruses. Clinical Virology Manual, 3rd Edition. S. Specter, R.L. Hodinka, S.A. Young, (eds.), ASM Press. Washington, D.C., pp. 235-251.

CPT Codes

87502
LOINC:  Influenza A 85477-8, Influenza B 85478-6, Flu A 80382-5, Flu B 80383-3

Contacts

Last Updated

1/30/2024