Elsevier

The Lancet

Volume 354, Issue 9186, 9 October 1999, Pages 1277-1282
The Lancet

Seminar
Influenza

https://doi.org/10.1016/S0140-6736(99)01241-6Get rights and content

Summary

Influenza is the most frequent cause of acute respiratory illness requiring medical intervention because it affects all age groups and because it can recur in any individual. During the past three decades, efforts to prevent and control influenza have focused primarily on the use of inactivated influenza vaccines in elderly people and in individuals with chronic medical conditions that put them at risk for complications. However, the continuing impact of influenza in these and other population groups has motivated the development of novel approaches for prevention and control of influenza. Several important advances in the field of influenza have occurred in the last few years. An experimental live, attenuated, intranasally administered trivalent influenza vaccine was shown to be highly effective in protecting young children against influenza A H3N2 and influenza B. New antiviral drugs based on the structure of the neuraminidase molecule were assessed in clinical trials and found to be effective against influenza A and B viruses. The expected use of these new antiviral agents has accelerated the development of rapid point-of-care diagnostic tests. The availability of new diagnostic tests, new antiviral drugs, and new vaccines will undoubtedly alter our approaches to influenza control and have an impact on clinical practice.

Section snippets

Virology

Influenza viruses are enveloped particles with two surface glycoproteins—haemagglutinin and neuraminidase. Influenza viruses belong to the family Orthomyxoviridae, which includes four genera: influenzavirus A, influenzavirus B, influenzavirus C, and thogotovirus.3 Influenza A and B viruses contain eight single-stranded, negative-sense RNA segments that encode at least ten polypeptides, of which eight are structural viral proteins, and two are found in infected cells.

Influenza A viruses are

Epidemiology

Influenza viruses are unique in their ability to cause both recurrent annual epidemics and more serious pandemics that spread rapidly and may affect all or most age-groups. The size of epidemics and pandemics, and their relative impact, reflects the interplay beween the extent of antigenic variation of the virus, the amount of protective immunity in populations, and the relative virulence of the viruses. Although the epidemiology of influenza has been studied extensively since the virus was

Clinical illness and complications

Influenza in adults and adolescents typically presents with an abrupt onset of fever and chills, accompanied by headache and sore throat, myalgias, malaise, anorexia, and a dry cough. Fever (38–40°C) peaks within 24 h of onset and lasts 1–5 days. Physical signs include the appearance of being unwell, hot and moist skin, flushed face, injected eyes, hyperaemic mucous membranes, and a clear nasal discharge. Although several of the symptoms of influenza are common to all age-groups, a review of

Laboratory diagnosis

A definitive diagnosis of influenza requires laboratory confirmation. There are several new diagnostic tests for influenza available or soon to be available. Diagnostic tests for influenza fall into four broad categories: virus isolation, detection of viral proteins, detection of viral nucleic acid, and serological diagnosis. The best clinical sample to use with the first three diagnostic methods is a combination of nasopharyngeal and throat swabs. The importance of appropriate collection and

Control and prevention

The two approaches available for the control and prevention of influenza are the use of vaccines and the use of antiviral agents.

References (47)

  • KG Nicholson

    Human influenza

  • PF Wright et al.

    Influenza A infections in young children

    N EnglJ Med

    (1977)
  • RH Parrot et al.

    Serious respiratory tract illness as a result of Asian influenza and influenza B infections in children

    J Pediatr

    (1962)
  • AA Kerr et al.

    Gastric ‘flu’ influenza B causing abdominal symptoms in children

    Lancet

    (1957)
  • DA Price et al.

    Influenzavirus A2 infections presenting with febrile convulsions and gastrointestinal symptoms in young children

    Clin Pediatr

    (1976)
  • JW Paisley et al.

    Type A2 influenza viral infections in children

    Am J Dis Child

    (1978)
  • NMcK Bennett

    Diagnosis of influenza

    MedJ Aust

    (1973)
  • J Woodall et al.

    Age and Asian influenza, 1957

    BMJ

    (1958)
  • PF Wright et al.

    Comparison of influenza B/Hong Kong virus infections among infants, children, and young adults

    J Infect Dis

    (1980)
  • R Dagan et al.

    Influenza A virus infection imitating bacterial sepsis in early infancy

    Pediatr Infect Dis J

    (1984)
  • DY Sanders et al.

    Outbreak of influenza A2 (Hong Kong strain) in a children's home

    South Med J

    (1970)
  • HL Blumenfeld et al.

    Studies in influenza in the pandemic of 1957–1958, I: an epidemiologic, clinical and serologic investigation of an intrahospital epidemic, with a note on vaccination efficacy

    J Clin Invest

    (1959)
  • AR Falsey et al.

    Respiratory syncytial virus and influenza A infections in the hospitalized elderly

    J Infect Dis

    (1995)
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