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.

–45–910–1920–3940–4950–5950–69> 70 Age groups (year) Respiratory complications (%) 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 complications in 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 groupExcess hospitalisation per 1000 Under 1 year19 1 to < 3 years8 3 to < 15 years2 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 consequences of 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 870 Associated cardiovascular and pulmonary disease 481 Associated cardiovascular disease and diabetes 104Cardiovascular disease 2Healthy adults 240 Pulmonary disease Barker WH et al. Arch Intern Med 1982; 142: 85–9.

By courtesy of APACI Asia-Pacific Advisory Committee on influenza