What is the treatment for swine influenza in individuals who work with pigs?

Treatment of Swine Influenza in Pig Workers

Individuals who work with pigs and develop swine influenza should be treated immediately with oseltamivir 75 mg orally twice daily for 5 days, initiated as soon as possible after symptom onset, ideally within 48 hours. 1, 2

Immediate Antiviral Treatment

• Start oseltamivir 75 mg twice daily for 5 days as soon as swine influenza is suspected in any pig worker presenting with influenza-like illness (fever >38°C plus respiratory symptoms such as cough or nasal symptoms). 1, 2

• Treatment should begin within 48 hours of symptom onset for maximum benefit, though hospitalized or severely ill patients may benefit even when started beyond this window. 1, 2

• Do not delay treatment waiting for laboratory confirmation—clinical suspicion based on occupational exposure to pigs and influenza-like symptoms is sufficient to initiate therapy. 2

• Dose adjustment is required for renal impairment: reduce to 75 mg once daily if creatinine clearance is <30 mL/minute. 1, 3

Alternative Antiviral Options

• Zanamivir 10 mg (two inhalations) twice daily for 5 days may be used if oseltamivir is unavailable or contraindicated, though it requires the patient to be able to use the diskhaler device properly. 1, 2

• Amantadine and rimantadine should NOT be used as first-line agents due to widespread resistance among circulating influenza A viruses, including swine influenza strains. 1

• M2 inhibitors (amantadine/rimantadine) might be considered only if neuraminidase inhibitors are completely unavailable AND the specific swine influenza strain is known to be susceptible. 1

Post-Exposure Chemoprophylaxis for High-Risk Contacts

• Pig workers with high-risk exposure to confirmed swine influenza cases should receive oseltamivir 75 mg once daily for 7-10 days after last known exposure. 1, 2

• High-risk exposures include unprotected close contact with infected pigs or infected humans, particularly in enclosed spaces without adequate personal protective equipment. 1, 2

• Chemoprophylaxis should begin as soon as the exposure is identified and continue for the full 7-10 day period after the last contact. 1, 2

Antibiotic Management

• Do NOT routinely prescribe antibiotics for uncomplicated swine influenza with respiratory symptoms alone. 1, 3, 4

• Consider antibiotics only if secondary bacterial infection develops, indicated by: recrudescent fever after initial improvement, increasing dyspnea, new focal chest signs suggesting pneumonia, or failure to improve after 48-72 hours. 1, 3

• First-line antibiotic choices when bacterial superinfection is suspected include co-amoxiclav or a tetracycline (such as doxycycline). 1

• Macrolides (clarithromycin or erythromycin) or fluoroquinolones active against Streptococcus pneumoniae and Staphylococcus aureus are alternative options for penicillin-allergic patients. 1

Clinical Monitoring and Supportive Care

• Monitor temperature, respiratory rate, pulse, blood pressure, oxygen saturation, and mental status at least twice daily in hospitalized patients, more frequently if severe illness develops. 1, 4

• Provide supportive care including antipyretics for fever control, adequate hydration, and nutritional support in severe or prolonged illness. 1, 3

• Assess for cardiac complications and volume depletion, particularly in patients with underlying chronic conditions. 1

Critical Pitfalls to Avoid

• Never wait for laboratory confirmation before starting oseltamivir in pig workers with influenza-like illness during periods when swine influenza is circulating. 2

• Do not use amantadine or rimantadine as first-line therapy given high resistance rates documented in recent surveillance (>90% of influenza A viruses in 2007-2008 season). 1

• Avoid prescribing antibiotics prophylactically for uncomplicated influenza, as this promotes antimicrobial resistance without clinical benefit. 3, 4

• Do not assume absence of fever rules out influenza in elderly or immunocompromised pig workers, as these populations may not mount adequate febrile responses. 1, 3

Seasonal Influenza Vaccination

• All pig workers should receive annual seasonal influenza vaccination to reduce the theoretical risk of co-infection with human and swine influenza viruses, which could facilitate viral reassortment and emergence of pandemic strains. 1

• Vaccination should occur before the influenza season begins (September through mid-November) to ensure adequate immunity. 1