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Disease Categories > Infectious Disease > Viruses

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Respiratory Viruses

Viral respiratory tract infections are the most common diseases affecting humans throughout the world.

More than 5 million children under the age of 6 experience lower respiratory infections (LRI) each year in the U.S.
Between 50-90% of LRI in children are caused by viruses
Viruses are the fourth leading cause of hospital-treated pneumonia in otherwise healthy adults

Infants, the elderly, and individuals with compromised cardiac, pulmonary or immune systems are at greatest risk of serious complications from these viruses.

Although a wide variety of viral agents are capable of causing lower respiratory infections (LRI) in adults and children, RSV, influenza A and B, Parainfluenza 1, 2, and 3 and adenovirus cause 80-90% of LRI.

Of particular importance are RSV and influenza, agents that are associated with significant morbidity and mortality and for which therapies are available
- RSV causes 50-90% of cases of bronchiolitis and 5-40% of cases of pneumonitis in children
- Influenza can cause significant disease in adults and children

Indications for Ordering

Tests generally appear in the order most useful for common clinical situations
Click on number for test-specific information in the ARUP Laboratory Test Directory

Test Name and Number	Recommended Use	Limitations	Follow Up
Respiratory Virus Mini Panel by RT-PCR 0060764 Method: Reverse Transcription Polymerase Chain Reaction	Identify respiratory virus responsible for disease; includes testing for influenza A & B and respiratory syncytial virus (RSV) PCR is a rapid and highly sensitive test for viruses PCR is also the most expensive test	A negative result does not rule out the presence of PCR inhibitors in the patient specimen or respiratory viral DNA concentrations below the level of detection by the assay
Viral Culture 0065008 Method: Cell Culture	Considered the gold standard for identifying viral agent responsible for infection Order if DFA test result is negative	Viral culture requires about 24-72 hours with most of these agents
Respiratory Viruses DFA 0060289 Method: Direct Fluorescent Antibody Stain	Rapid test for detecting adenovirus, influenza A and B, respiratory syncytial virus and parainfluenza 1, 2 and 3 viruses Significantly more rapid and less expensive than PCR	The adequacy of the direct specimen significantly influences the sensitivity of the DFA Naso-pharyngeal aspirate or other respiratory secretion must contain intact respiratory epithelium to be deemed adequate for examination Inadequate specimen collection and too few cells on the slide may lead to failure of direct smears to detect respiratory viruses Excess mucus or lumpy smears can cause: False-positives by nonspecifically trapping the antibody reagent False-negatives by clumping the cells, thereby masking the virus antigens	Viral Culture of DFA-negative specimens is strongly recommended Refer to Respiratory Viruses DFA with Reflex to Viral Culture

Additional Information

In general, the sensitivity of DFA testing for influenza, parainfluenza and respiratory adenovirus improves with specimen type (e.g., true sputum and nasopharyngeal are better than throat swabs).

Guidelines

Prevention and control of influenza. Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2007. Centers for Disease Control and Prevention - Federal Government Agency [U.S.]. 1984 Apr (revised 2007 Jun 29). 54 pages. NGC:005730 (Link to NGC)

General References

Bader MS, McKinsey DS. Viral infections in the elderly. The challenges of managing herpes zoster, influenza, and RSV. Postgrad Med. 2005;118(5):45-4. (Link to PubMed)

Call SA, Vollenweider MA, Hornung CA, Simel DL, McKinney WP. Does this patient have influenza?. JAMA. 2005;293(8):987-997. (Link to PubMed)

Crowe JE Jr, Williams JV. Immunology of viral respiratory tract infection in infancy. Paediatr Respir Rev. 2003;4(2):112-119. (Link to PubMed)

Demicheli V, Rivetti D, Deeks JJ, Jefferson TO. Vaccines for preventing influenza in healthy adults. Cochrane Database Syst Rev. 2004;(3):CD001269. (Link to PubMed)

Henrickson KJ. Cost-effective use of rapid diagnostic techniques in the treatment and prevention of viral respiratory infections. Pediatr Ann. 2005;34(1):24-31. (Link to PubMed)

Henrickson KJ. Parainfluenza viruses. Clin Microbiol Rev. 2003;16(2):242-264. (Link to PubMed)

Monto AS. Occurrence of respiratory virus: time, place and person. Pediatr Infect Dis J. 2004;23(1 Suppl):S58-S64. (Link to PubMed)

Ventre K, Randolph A. Ribavirin for respiratory syncytial virus infection of the lower respiratory tract in infants and young children. Cochrane Database Syst Rev. 2004;(4):CD000181. (Link to PubMed)

References from the ARUP Institute for Clinical and Experimental Pathology®

Taggart EW, Hill HR, Martins TB, Litwin CM. Comparison of complement fixation with two enzyme-linked immunosorbent assays for the detection of antibodies to respiratory viral antigens. Am J Clin Pathol. 2006;125(3):460-466. (Link to PubMed)

Reviewed by

Hillyard, David R., M.D. Medical Director, Molecular Infectious Diseases at ARUP Laboratories; Associate Professor, Pathology, University of Utah

Petti, Cathy A., M.D. Medical Director, Infectious Diseases at ARUP Laboratories; Assistant Professor, Pathology and Medicine, University of Utah

Comprehensive Review: September 2007
Last Update: March 2008