Elsevier Health Sciences

Topics

« Back to Resource Center

Pathogenesis, Clinical Features and Diagnosis

Influenza in susceptible subgroups

Table 6 summarizes the high-risk populations for significant morbidity and mortality from influenza. These groups should be targeted for vaccination and other means of prophylaxis, as well as optimal disease management. Additional prophylaxis strategies include encouraging vaccination of close contacts of these individuals. These include family members and other household or institutional contacts.

Table 6 People at high risk of hospitalization or death from influenza. source: Adapted from World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 2000;75:281–288.

People at high risk of hospitalization or death from influenza
People in specific age categories
  • adults aged 65 years and older
  • children under age 2 years
People with chronic disease
  • chronic pulmonary disease (asthma, bronchitis, emphysema, tuberculosis)
  • chronic cardiovascular disease
  • diabetes mellitus
  • renal disease
Immunocompromised people
  • transplant recipients
  • HIV-positive people
  • splenic dysfunction
Pregnant women

References in context

  • Table 6 summarizes the high-risk populations for significant morbidity and mortality from influenza.
    Go to context

Children

Influenza attack rates are higher in children compared to adults. High-grade fever, cervical lymphadenopathy, and nausea and vomiting are frequent manifestations of influenza in children. Drowsiness (uncommon in adults) occurs in about 50% of infants under 4 years of age, and in up to 10% of 5–14-year-olds. Otitis media is frequently present (25% overall), particularly in those prone to middle-ear infections (67% in 1- to 3-year-olds). In infants (under 5 years old), 5–10 per thousand are hospitalized with respiratory symptoms (acute bronchitis, croup, pneumonia), and one in 5000 dies during influenza epidemics.

Infants and children under the age of 2 years will generally have a naive immune system and potentially compromised ability to mount an effective immune response to influenza. Morbidity and mortality are highest in this paediatric population. Additional common risk factors are related to asthma and type 1 diabetes, as well as immunocompromising conditions, although these are less common. School absentee rates can exceed 50% during influenza epidemics and provide evidence of the highly contagious nature of this illness. The diagnostic accuracy of influenza in children and the relationship to diagnostic testing has been recently reviewed. 19 x TM Uyeki. Influenza diagnosis and treatment in children: a review of studies on clinically useful tests and antiviral treatment for influenza. Pediatr Infect Dis J 22 (2003) (164 - 177)

Older adults and adults with chronic diseases

Elderly patients experience more lower respiratory tract symptoms, with productive cough, wheeze and chest pain. In older adults, cough is the most common presenting symptom (>80% of cases), while fever is much less common compared to young adults. Considering that older people may lose 2–3% of muscle power per day of bed rest, significant disability may result from influenza. It is therefore not surprising that influenza and pneumonia represent one of the six leading causes of catastrophic disability in the population of 65 years and above. 20 x L Ferrucci, JM Guralnik, M Pahor, MC Corti, RJ Havlik. Hospital diagnoses, Medicare charges, and nursing home admissions in the year when older persons become severely disabled [see comments]. J Am Med Assoc 277 (1997) (728 - 734) Gastrointestinal symptoms also tend to be more common, especially with influenza B. Between four and 10 elderly patients per thousand are hospitalized. Recent studies have linked annual outbreaks of influenza to excess mortality during the winter months due to heart attacks, strokes, and exacerbations of diabetes and congestive heart failure during the winter months in the population of 70 years and older. 21, x TA Reichert, L Simonsen, A Sharma, et al.. Influenza and the winter increase in mortality in the United States, 1959–1999. Am J Epidemiol 160 (2004) (492 - 502) Crossref. 22 x DM Fleming, KW Cross, RS Pannell. Influenza and its relationship to circulatory disorders. Epidemiol Infect 133 (2005) (255 - 262) Crossref. These observations point to a potentially enhanced inflammatory basis of influenza illness and related complications in older people.

As indicated above, influenza also poses increased risks to elderly (>65 years old) with chronic medical conditions. In these patients, influenza may occur as a serious illness, with exacerbation of the underlying disease and possibly a fatal outcome (reviewed in Ref. 23). Cough is the most common presenting symptom of influenza in this population and presents a diagnostic challenge to the physician. 24 x J Widdicombe, S Kamath. Acute cough in the elderly: aetiology, diagnosis and therapy. Drugs Aging 21 (2004) (243 - 258) Crossref. More than 90% of influenza-associated excess deaths occur in the elderly of 65 years and older, and thus prevention, diagnosis and appropriate management of illness have a significant impact on health outcomes in this population. 25 x JP Janssens, KH Krause. Pneumonia in the very old. Lancet Infect Dis 4 (2004) (112 - 124) Crossref. People aged 50–65 years are also at greater risk due to the increased rate of chronic medical conditions, such as diabetes and cardiac, pulmonary or renal diseases, and immunocompromising conditions or medications. All of these conditions are associated with a significant increase in risk of hospitalization and death due to influenza, and also require optimal disease management along with vaccination for the prevention of influenza illness.

Immunocompromised patients

Influenza is more common in immunocompromised individuals (32%) than community controls (14%) and can cause severe disease. 26 x RA Vilchez, J Fung, S Kusne. The pathogenesis and management of influenza virus infection in organ transplant recipients. Transpl Infect Dis 4 (2002) (177 - 182) Crossref. Pneumonia (usually viral) is more common and mortality is higher. In a study of adults with leukaemia and adult recipients of haematopoietic stem cell transplants, severe lymphopenia, elderly age, receipt of an allogeneic haematopoietic stem cell transplant and concurrent opportunistic infections were identified as independent risk factors for a complicated course. Prolonged shedding of influenza virus (up to 5 months) and rapid emergence of resistance to amantadine and rimantadine (see Chapter 7) have been observed in immunocompromised individuals. 27 x JA Englund, RE Champlin, PR Wyde, et al.. Common emergence of amantadine- and rimantadine-resistant influenza A viruses in symptomatic immunocompromised adults. Clin Infect Dis 26 (1998) (1418 - 1424) HIV infection is not generally associated with more severe influenza illness.

Pregnant women

Women in the second or third trimester of pregnancy have an increased risk of hospitalization due to cardiorespiratory complications. 28 x WS Lim, JT Macfarlane, CL Colthorpe. Treatment of community-acquired lower respiratory tract infections during pregnancy. Am J Respir Med 2 (2003) (221 - 233) Crossref. The risk is greatest in pregnant women with mitral valve disease, who have a 45% mortality rate associated with influenza infection (higher if labour occurs during influenza infection).

 
x

Table 6 People at high risk of hospitalization or death from influenza. source: Adapted from World Health Organization. Influenza vaccines. Wkly Epidemiol Rec 2000;75:281–288.

People at high risk of hospitalization or death from influenza
People in specific age categories
  • adults aged 65 years and older
  • children under age 2 years
People with chronic disease
  • chronic pulmonary disease (asthma, bronchitis, emphysema, tuberculosis)
  • chronic cardiovascular disease
  • diabetes mellitus
  • renal disease
Immunocompromised people
  • transplant recipients
  • HIV-positive people
  • splenic dysfunction
Pregnant women

References in context

  • Table 6 summarizes the high-risk populations for significant morbidity and mortality from influenza.
    Go to context

References

Label Authors Title Source Year
19

References in context

  • Infants and children under the age of 2 years will generally have a naive immune system and potentially compromised ability to mount an effective immune response to influenza.
    Go to context

TM Uyeki. Influenza diagnosis and treatment in children: a review of studies on clinically useful tests and antiviral treatment for influenza. Pediatr Infect Dis J 22 (2003) (164 - 177) 2003
20

References in context

  • It is therefore not surprising that influenza and pneumonia represent one of the six leading causes of catastrophic disability in the population of 65 years and above.20 Gastrointestinal symptoms also tend to be more common, especially with influenza B.
    Go to context

L Ferrucci, JM Guralnik, M Pahor, MC Corti, RJ Havlik. Hospital diagnoses, Medicare charges, and nursing home admissions in the year when older persons become severely disabled [see comments]. J Am Med Assoc 277 (1997) (728 - 734) 1997
21

References in context

  • Recent studies have linked annual outbreaks of influenza to excess mortality during the winter months due to heart attacks, strokes, and exacerbations of diabetes and congestive heart failure during the winter months in the population of 70 years and older.21,22 These observations point to a potentially enhanced inflammatory basis of influenza illness and related complications in older people.
    Go to context

TA Reichert, L Simonsen, A Sharma, et al.. Influenza and the winter increase in mortality in the United States, 1959–1999. Crossref. Am J Epidemiol 160 (2004) (492 - 502) 2004
22

References in context

  • Recent studies have linked annual outbreaks of influenza to excess mortality during the winter months due to heart attacks, strokes, and exacerbations of diabetes and congestive heart failure during the winter months in the population of 70 years and older.21,22 These observations point to a potentially enhanced inflammatory basis of influenza illness and related complications in older people.
    Go to context

DM Fleming, KW Cross, RS Pannell. Influenza and its relationship to circulatory disorders. Crossref. Epidemiol Infect 133 (2005) (255 - 262) 2005
24

References in context

  • Cough is the most common presenting symptom of influenza in this population and presents a diagnostic challenge to the physician.24 More than 90% of influenza-associated excess deaths occur in the elderly of 65 years and older, and thus prevention, diagnosis and appropriate management of illness have a significant impact on health outcomes in this population.25 People aged 50–65 years are also at greater risk due to the increased rate of chronic medical conditions, such as diabetes and cardiac, pulmonary or renal diseases, and immunocompromising conditions or medications.
    Go to context

J Widdicombe, S Kamath. Acute cough in the elderly: aetiology, diagnosis and therapy. Crossref. Drugs Aging 21 (2004) (243 - 258) 2004
25

References in context

  • Cough is the most common presenting symptom of influenza in this population and presents a diagnostic challenge to the physician.24 More than 90% of influenza-associated excess deaths occur in the elderly of 65 years and older, and thus prevention, diagnosis and appropriate management of illness have a significant impact on health outcomes in this population.25 People aged 50–65 years are also at greater risk due to the increased rate of chronic medical conditions, such as diabetes and cardiac, pulmonary or renal diseases, and immunocompromising conditions or medications.
    Go to context

JP Janssens, KH Krause. Pneumonia in the very old. Crossref. Lancet Infect Dis 4 (2004) (112 - 124) 2004
26

References in context

  • Influenza is more common in immunocompromised individuals (32%) than community controls (14%) and can cause severe disease.26 Pneumonia (usually viral) is more common and mortality is higher.
    Go to context

RA Vilchez, J Fung, S Kusne. The pathogenesis and management of influenza virus infection in organ transplant recipients. Crossref. Transpl Infect Dis 4 (2002) (177 - 182) 2002
27

References in context

  • Prolonged shedding of influenza virus (up to 5 months) and rapid emergence of resistance to amantadine and rimantadine (see Chapter 7) have been observed in immunocompromised individuals.27 HIV infection is not generally associated with more severe influenza illness.
    Go to context

JA Englund, RE Champlin, PR Wyde, et al.. Common emergence of amantadine- and rimantadine-resistant influenza A viruses in symptomatic immunocompromised adults. Clin Infect Dis 26 (1998) (1418 - 1424) 1998
28

References in context

  • Women in the second or third trimester of pregnancy have an increased risk of hospitalization due to cardiorespiratory complications.28 The risk is greatest in pregnant women with mitral valve disease, who have a 45% mortality rate associated with influenza infection (higher if labour occurs during influenza infection).
    Go to context

WS Lim, JT Macfarlane, CL Colthorpe. Treatment of community-acquired lower respiratory tract infections during pregnancy. Crossref. Am J Respir Med 2 (2003) (221 - 233) 2003

« Back to Resource Center