INFLUENZA COMPLICATIONS

Influenza complications

• Bacterial superinfections

– bacterial pneumonia– croup– respiratory disorders

• Decompensation of chronic diseases

– pulmonary disease– heart disease– renal insufficiency– metabolic disease

Nicholson KG. Semin Respir Infect 1992; 7: 26–37.

• Upper respiratory tract infection (URTI)– otitis media – sinusitis

• Lower respiratory tract infection (LRTI)– exacerbation of asthma/chronic obstructive pulmonary

disease (COPD)– croup, bronchiolitis– primary viral pneumonia (rare*)– secondary bacterial pneumonia

Influenza – respiratory complications

*5–10% of pneumonia is an influenza complication

Influenza complications• Primary viral pneumonia• Bacterial secondary pneumonia• Tracheobronchitis• Bronchiolitis• Congestive heart failure• Myocarditis, pericarditis• Complications of sinus, middle ear, musculature • Reye’s syndrome – in children• Ketoacidosis – in diabetics• Acute viral encephalitis – in children• Guillain Barre syndrome• Gastrointestinal bleeding – in children• Decompensation of pre-existing pathology• Excess mortality• Possible association with prenatal exposure and schizophrenia

Groups at higher risk of complications

• Elderly (> 60 years of age), especially in residential care units• Children and teenagers (6 months–18 years of age) receiving

long-term aspirin therapy• Pregnant women belonging to high-risk groups• Patients with:

– chronic respiratory disease, e.g. asthma, COPD– chronic heart disease– chronic metabolic disease, e.g. diabetes mellitus– immunosuppression due to treatment or disease, e.g. HIV– haematological disorders– chronic renal failure

Palache AM. Influenza subunit vaccine - ten years experience. Eur J Clin Res 1992; 3: 117–38.

0

20

40

60

80

0–4 5–9 10–19 20–39 40–49 50–59 50–69 > 70

Age groups (year)

Res

pir

ato

ry

com

pli

cati

on

s (%

)

Age distribution of respiratory complications

Betts FR et al. In: Mandell GL et al., eds. Principles and Practice of Infectious Diseases.3rd Edn. New York: Churchill Livingstone; 1990: 1306–25.

Influenza complicationsin children• Higher fever than in adults• Higher incidence of coryza, otitis media and

gastrointestinal manifestations• Influenza may present as croup or bronchiolitis• Higher incidence of drowsiness and delirium• Complications like myositis and pneumonia are more

frequent

Nicholson KG. Semin Respir Infect 1992; 7: 26–37.

Severe symptoms in children

30%

Bronchiolar, pulmonary signs

40%

Vomiting, diarrhoea

50%

Pharyngitis

90%

Fever, rhinitis

Kilbourne ED. Influenza. New York: Plenum Medical Book Company; 1987: 157–66.

• Retrospective cohort study, Tennessee Medicaid program (1973–1993)• Children under 15 with medically treated asthma or chronic medical conditions

Age group Excess hospitalisation

per 1000

Under 1 year 19

1 to < 3 years 8

3 to < 15 years 2

Yearly excess hospitalisation for cardiopulmonary disease due to influenza in

different age group per 1000 high risk children

•Influenza morbidity is high in this class of patient,and often underestimated

Other yearly consequencesof influenza

Influenza in children with asthma and other chronic medical conditions

• Outpatients visits– 120 to 200 per 1000 at-

risk children • Antibiotic courses

– 65 to 140 per 1000 at-risk children

Neuzil KM et al. J Pediatr 2000; 137: 856–64.

Influenza in pregnancy

• Severe pulmonary complications and death for pregnant woman

• Foetal loss and abortion• Other risks

– foetal complications (growth, weight, etc.)– brain damage– neural tube defects

Possible consequences:

Vulnerability during the second and third trimester

Anonymous. Lancet 1994; 343: 665; Lynberg MC et al. Am J Epidemiol 1994; 140: 244–55; Takei N et al. Eur Arch Psychiatry Clin Neurosci 1995; 245: 255–9; Wright P et al. Am J Psychiatry 1995; 152: 1714–20.

Pneumonia and influenza associated death

870Associated cardiovascular and pulmonary disease

481Associated cardiovasculardisease and diabetes

104Cardiovascular disease

2Healthy adults

240Pulmonary disease

Barker WH et al. Arch Intern Med 1982; 142: 85–9.

By courtesy of APACIAsia-Pacific Advisory Committee on influenzawww.apaci-flu.com