Diagnosis of seasonal influenza in adults
- Raphael Dolin, MD
Raphael Dolin, MD
- Professor of Medicine
- Harvard Medical School
Influenza is an acute respiratory illness caused by influenza A or B viruses that occurs in outbreaks and epidemics worldwide, mainly during the winter season. Signs and symptoms of upper and/or lower respiratory tract involvement are present, along with indications of systemic illness such as fever, headache, myalgia, and weakness. Although acutely debilitating, influenza is a self-limited infection in the general population. However, it is associated with increased morbidity and mortality in certain high-risk populations.
In certain circumstances, the diagnosis of influenza can be made clinically, such as during an outbreak. At other times, it is important to establish the diagnosis using laboratory testing quickly, such as in the hospitalized patient with acute onset of severe pulmonary disease.
The diagnosis of seasonal influenza in adults will be reviewed here. The diagnosis of this infection in children is discussed separately. The epidemiology, clinical manifestations, prevention, and treatment of seasonal influenza infection, as well as the diagnosis of pandemic H1N1 influenza ("swine influenza") and avian influenza, are reviewed elsewhere. (See "Seasonal influenza in children: Clinical features and diagnosis" and "Epidemiology of influenza" and "Clinical manifestations of seasonal influenza in adults" and "Seasonal influenza vaccination in adults" and "Prevention of seasonal influenza with antiviral drugs in adults" and "Infection control measures to prevent seasonal influenza in healthcare settings" and "Treatment of seasonal influenza in adults" and "Clinical manifestations and diagnosis of pandemic H1N1 influenza ('swine influenza')" and "Clinical manifestations and diagnosis of avian influenza".)
During outbreaks — During an influenza outbreak, acute febrile respiratory illnesses brought to the attention of clinicians can be diagnosed as influenza with a high degree of certainty by clinical criteria. This was demonstrated in the following studies:
●In a retrospective pooled analysis of signs and symptoms in 3744 adolescents and adults with an influenza-like illness who participated in phase II and III trials of neuraminidase inhibitors during outbreaks . The best multivariate predictor was the combination of fever and cough within 48 hours of the development of symptoms, which had a positive predictive value of 79 percent for documented influenza.
- Monto AS, Gravenstein S, Elliott M, et al. Clinical signs and symptoms predicting influenza infection. Arch Intern Med 2000; 160:3243.
- Boivin G, Hardy I, Tellier G, Maziade J. Predicting influenza infections during epidemics with use of a clinical case definition. Clin Infect Dis 2000; 31:1166.
- Nicholson KG, Kent J, Hammersley V, Cancio E. Acute viral infections of upper respiratory tract in elderly people living in the community: comparative, prospective, population based study of disease burden. BMJ 1997; 315:1060.
- Call SA, Vollenweider MA, Hornung CA, et al. Does this patient have influenza? JAMA 2005; 293:987.
- Govaert TM, Dinant GJ, Aretz K, Knottnerus JA. The predictive value of influenza symptomatology in elderly people. Fam Pract 1998; 15:16.
- Walsh EE, Cox C, Falsey AR. Clinical features of influenza A virus infection in older hospitalized persons. J Am Geriatr Soc 2002; 50:1498.
- US Centers for Disease Control and Prevention. Guidance for clinicians on the use of rapid influenza diagnostic tests. http://www.cdc.gov/flu/professionals/diagnosis/clinician_guidance_ridt.htm (Accessed on April 04, 2012).
- Paules C, Subbarao K. Influenza. Lancet 2017.
- Harper SA, Bradley JS, Englund JA, et al. Seasonal influenza in adults and children--diagnosis, treatment, chemoprophylaxis, and institutional outbreak management: clinical practice guidelines of the Infectious Diseases Society of America. Clin Infect Dis 2009; 48:1003.
- Hurt AC, Alexander R, Hibbert J, et al. Performance of six influenza rapid tests in detecting human influenza in clinical specimens. J Clin Virol 2007; 39:132.
- Ikenaga M, Kosowska-Shick K, Gotoh K, et al. Genotypes of macrolide-resistant pneumococci from children in southwestern Japan: raised incidence of strains that have both erm(B) and mef(A) with serotype 6B clones. Diagn Microbiol Infect Dis 2008; 62:16.
- Chartrand C, Leeflang MM, Minion J, et al. Accuracy of rapid influenza diagnostic tests: a meta-analysis. Ann Intern Med 2012; 156:500.
- Centers for Disease Control and Prevention. Evaluation of 11 commercially available rapid influenza diagnostic tests--United States, 2011-2012. MMWR Morb Mortal Wkly Rep 2012; 61:873.
- Sintchenko V, Gilbert GL, Coiera E, Dwyer D. Treat or test first? Decision analysis of empirical antiviral treatment of influenza virus infection versus treatment based on rapid test results. J Clin Virol 2002; 25:15.
- US Centers for Disease Control and Prevention. H1N1 clinicians questions and answers. http://www.cdc.gov/h1n1flu/vaccination/clinicians_qa.htm (Accessed on April 14, 2011).
- Landry ML, Cohen S, Ferguson D. Real-time PCR compared to Binax NOW and cytospin-immunofluorescence for detection of influenza in hospitalized patients. J Clin Virol 2008; 43:148.
- McGeer AJ. Diagnostic testing or empirical therapy for patients hospitalized with suspected influenza: what to do? Clin Infect Dis 2009; 48 Suppl 1:S14.
- Centers for Disease Control and Prevention. Guidance for clinicians on the use of RT-PCR and other molecular assays for diagnosis of influenza virus infection. http://www.cdc.gov/flu/professionals/diagnosis/molecular-assays.htm (Accessed on September 06, 2017).
- New CDC-developed diagnostic lab test for flu approved. http://www.cdc.gov/media/releases/2011/p0902_diag_lab.html?s_cid=2011_p0902_diag_lab.htm (Accessed on August 17, 2016).
- FDA news release. FDA grants first CLIA waiver for nucleic acid-based flu diagnostic test. http://www.fda.gov/newsevents/newsroom/pressannouncements/ucm429127.htm (Accessed on January 12, 2015).
- Covalciuc KA, Webb KH, Carlson CA. Comparison of four clinical specimen types for detection of influenza A and B viruses by optical immunoassay (FLU OIA test) and cell culture methods. J Clin Microbiol 1999; 37:3971.
- Treanor JJ. Influenza (including avian influenza and swine influenza). In: Principles and Practice of Infectious Diseases, 8th ed, Bennett JE, Dolin R, Blaser MJ (Eds), Elsevier Saunders, Philadelphia 2015. p.2000.
- Dowdle WN, Kendal AP, Noble GR. Influenza viruses. In: Diagnostic procedures for viral, rickettsial, and chlamydial infections, Lenette EH, Schmidt NJ (Eds), American Public Health Association, Washington, D.C 1979. p.603.
- Centers for Disease Control and Prevention. Health Alert Network. CDC health update regarding treatment of patients with influenza with antiviral medications. http://emergency.cdc.gov/han/han00375.asp (Accessed on January 12, 2015).
- Centers for Disease Control and Prevention (CDC). Evaluation of rapid influenza diagnostic tests for influenza A (H3N2)v virus and updated case count--United States, 2012. MMWR Morb Mortal Wkly Rep 2012; 61:619.
- Centers for Disease Control and Prevention (CDC). CDC Health Advisory. Variant influenza virus (H3N2v) infections. http://emergency.cdc.gov/HAN/han00351.asp (Accessed on August 17, 2016).
- Lieberman D, Lieberman D, Shimoni A, et al. Identification of respiratory viruses in adults: nasopharyngeal versus oropharyngeal sampling. J Clin Microbiol 2009; 47:3439.
- CLINICAL DIAGNOSIS
- During outbreaks
- Sporadic cases
- Older adult patients
- LABORATORY TESTING
- Rapid antigen tests
- Nucleic acid tests
- Viral culture
- Serologic testing
- APPROACH TO DIAGNOSIS
- Whom to test
- - H3N2 variant viruses
- Type and handling of specimens
- Choice of diagnostic test
- Interpretation of results
- INFLUENZA ACTIVITY
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS