Epidemiology
- Incidence: 150.00 cases per 100,000 person-years
- Peak incidence: 40-50 years
- Sex ratio: 1:1
| Condition | Relative incidence |
|---|---|
| Influenza | 1 |
| Carbon monoxide poisoning | 0.02 |
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Clinical features
The following are typically seen:
- fever greater than 38ºC
- myalgia
- lethargy
- headache
- rhinitis
- sore throat
- cough
- diarrhoea and vomiting
Management
Consider prescribing antiviral treatment for influenza if all of the following apply:
Antivirals for influenza
*Chronic disease of respiratory, cardiac, renal, hepatic or neurological nature, diabetes, immunosuppression or have morbid obesity.
- 1) The patient is in an at-risk group* or is felt to be at risk of developing a serious complication
- 2) There is circulating influenza nationally
- 3) The patient is able to start treatment within 48 hours from the onset of symptoms (36 hours for zanamivir)
Antivirals for influenza
- First line: oseltamivir
- Second line: zanamivir
- For immunocompromised adults and in renal impairment: zanamivir
*Chronic disease of respiratory, cardiac, renal, hepatic or neurological nature, diabetes, immunosuppression or have morbid obesity.
Prognosis
The overall case-fatality rate for influenza is around 0.1%.