Influenza A & B (Rapid)
TECHNICAL UPDATE

DESCRIPTION/BACKGROUND INFORMATION:

Influenza is an acute, febrile viral illness caused by infection with influenza type A & B. Influenza is a communicable disease that is easily transmitted through the coughing and sneezing of aerosolized droplets containing the live virus. The onset of symptoms is abrupt, occurring one to two days after exposure. Symptoms may include fever of 101 to 106, chills, headaches, respiratory dry cough, nasal drainage, malaise, and muscle ache. Influenza infections are usually self-limited with symptoms lasting several days. Historically, influenza has caused epidemics about every one to three years for the last 400 years. Worldwide cases are estimated at 350 million per year. Epidemiologically, influenza type A predominates over type B. Type B appears intermittently. Important features are: the epidemic nature of the disease, the morbidity (complications), and the mortality associated with patients at higher risk for infection; i.e., elderly persons and persons with underlying health problems.

CLINICAL APPLICATION:

Early diagnosis may play a significant role toward improved management of patients at high risk for developing influenza-related complications. Antibiotics are frequently empirically prescribed for ambulatory patients complaining of upper respiratory infections, colds, and bronchitis. The majority of the time, these infections are of a viral origin and do not require antibiotic therapy. A rapid test for the detection of influenza A and B is of value in avoiding empirical therapy or prescribing appropriate therapy. Conventional culture methods require special transport to ensure viability and require days for results. This test is a rapid method for the detection of influenza types A and B viral antigen (nucleoprotein) from clinical specimens. Viable virus is not required for the detection of influenza A or B antigen with this test.

TEST NAME & NUMBER:

• Influenza A/B (Rapid)

METHODOLOGY:

Influenza A & B Nasal Aspirate Specimens:
(Preferred) (Rapid) Insert a depressed bulb syringe deeply into either nare and suction while with- drawing the bulb. Expel contents into a sterile container.

Sputum Specimens:
(Preferred)Obtain sputum by deep cough either spontaneously or following mechanical induction using a throat swab.

Nasopharyngeal Swab Specimens:
Insert a rayon nasopharyngeal swab beneath the inferior turbinate of either nare and vigorously rub and roll against the mucosal surface. Remove swab from nose and insert tip down into paper wrapper. Do NOT use calcium alginate nasopharyngeal swabs.

Throat Swab Specimens:
Vigorously rub a rayon throat swab on both tonsillar surfaces and the posterior pharynx. Remove swab from mouth and insert tip down into the paper wrapper. Swabs with wooden shafts, Culturette EZ swabs, or swabs with bacterial semi-solid, liquid, or charcoal transport media should NOT be used as they may interfere with test results.

SUBMISSION REQUIREMENTS:

Viral transport media will dilute specimens and should NOT be used with specimens to be run with this Rapid Influenza Tests. If a viral culture is also anticipated, please contact Client Services.

All specimens may be stored refrigerated (2-8 C) for up to 24 hours. EIA

REFERENCES:

1. Fetts FB. Orthyomyxovirdae-Influenza Virus. In: Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases. 4th ed. New York: Churchill Livingstone; 1995: 1546-1566.
2. Prevention and Control of Influenza, Recommendations of the Advisory Committee on Immunization Practices (ACIP). Morbidity and Mortality Weekly Report; Vol 45, No RR-5,
   May 3, 1996.
3. Gonzales R, et. al. Antibiotic Prescribing for Adults with Colds, Upper Respiratory Infections and Bronchitis by Ambulatory Care Physicians. JAMA 1997; 278:901-904.
4. Rota PA, et.al. Cocirculation of Two Evolutionary Lineages of Influenza Type B Virus Since 1983. Virology 1990; 175: 59-68.