Treatment of Influenza A with Prolonged Fever (6 Days)
For patients with influenza A and fever persisting for 6 days, antiviral treatment with a neuraminidase inhibitor (preferably oseltamivir) should be initiated immediately, and investigation for bacterial coinfection is strongly recommended.
Antiviral Treatment
- Oseltamivir (Tamiflu) is the preferred first-line treatment for influenza A, even when symptoms have been present for more than 48 hours, particularly in patients with severe or persistent symptoms 1
- Standard adult dosing is 75 mg twice daily for 5 days; pediatric dosing is weight-based (≤15 kg: 30 mg twice daily; >15-23 kg: 45 mg twice daily; >23-40 kg: 60 mg twice daily; >40 kg: 75 mg twice daily) 1
- For patients with persistent fever after 6 days, a longer duration of antiviral treatment may be considered, especially if there is evidence of ongoing viral replication 1
- While standard treatment duration is 5 days, clinicians should consider longer treatment for patients with severe disease, particularly those with respiratory complications 1
Investigation for Complications
- Persistent fever beyond 3-5 days strongly suggests a complication such as bacterial coinfection, which requires investigation and empiric treatment 1
- Clinicians should investigate and empirically treat bacterial coinfection in patients with influenza who have persistent fever, extensive pneumonia, respiratory failure, or hypotension 1
- Diagnostic testing should include respiratory specimens for bacterial culture, blood cultures, and chest imaging 2
- Patients who fail to improve after 3-5 days of antiviral treatment should be investigated for other causes besides influenza 1
Management of Persistent Fever
- Symptomatic treatment of fever should include paracetamol (acetaminophen) or ibuprofen (with caution) 3
- Antipyretics should not be used solely to reduce body temperature but rather to alleviate distressing symptoms 3
- Adequate hydration (drinking plenty of fluids, but no more than 2 liters per day) is recommended 3
Considerations for Antiviral Resistance
- For patients with persistent fever despite appropriate antiviral therapy, consider the possibility of antiviral resistance 1
- Influenza NAI resistance testing should be considered for patients with evidence of persistent influenza viral replication (e.g., after 7-10 days) who remain ill during or after NAI treatment 1
- In immunocompromised patients, viral shedding may be prolonged, and longer courses of antiviral therapy may be necessary 1
Special Considerations
- For critically ill patients with persistent symptoms, some experts recommend doubling the dose of oseltamivir (150 mg twice daily in adults), although evidence for this approach is limited 1, 4
- Intravenous antiviral therapy (peramivir) may be considered in severely ill patients who have progressed despite oral therapy or when there are concerns about oral absorption 1
- For patients with renal impairment (CrCl <30 mL/min), the dose of oseltamivir should be reduced to 75 mg once daily 1
Follow-up Recommendations
- Patients should be advised to seek immediate medical attention if they develop shortness of breath, painful or difficult breathing, bloody sputum, drowsiness, disorientation, or confusion 3
- Close monitoring is essential for patients with persistent fever to detect deterioration or complications early 2
Prevention of Transmission
- Patients should be advised on infection control measures to prevent transmission, including hand hygiene and respiratory etiquette 2
- Household contacts may benefit from post-exposure prophylaxis with oseltamivir if they are at high risk for complications 2
Remember that persistent fever beyond the typical duration of influenza illness (3-5 days) warrants thorough investigation for complications, particularly bacterial superinfection, which is a common cause of influenza-related mortality.