Human infection with avian influenza

Disease Description (Causes and Symptoms)

• Causes and pathophysiology
  • Avian influenza (AI) is caused by influenza viruses that infect birds, such as H5 and H7 strains (highly pathogenic HPAI / low pathogenic LPAI). Some strains (e.g., H5N1 and H7N9) can infect humans and replicate in the upper and lower respiratory tracts, causing symptoms ranging from mild respiratory symptoms to severe pneumonia, acute respiratory distress syndrome (ARDS), and multiorgan failure.
  • The main routes of infection are contact with the feces and bodily fluids of infected birds or contaminated objects (feed containers, feathers, eggshells, etc.), as well as respiratory inhalation. Processed and cooked poultry is generally safe (the virus is heat-sensitive: it is inactivated when heated at 75°C or higher for 5 minutes).
• Main symptoms
  • Incubation period: usually 3–7 days (up to approximately 10 days)
  • Early symptoms: flu-like symptoms such as fever (≥38°C), chills, muscle aches, cough, and sore throat
  • As the disease progresses: pneumonia, respiratory failure, shock, multiorgan failure, and possible death

Treatment and Precautions

• Antiviral medications
  • Standard treatment: influenza antiviral medications such as oseltamivir (Tamiflu) and zanamivir (Relenza) are used. Administration is recommended as early as possible (as soon as possible after symptom onset). In severe cases or hospitalized patients, treatment may still be given late for potential therapeutic benefit.
  • For exposed individuals (e.g., poultry culling workers), prophylactic antiviral medication may be considered in accordance with public health guidelines.
• Supportive treatment
  • For hypoxemia or respiratory distress: oxygen therapy, mechanical ventilation (if necessary), and intensive care (hemodynamic support, renal replacement therapy, etc.).
  • If a secondary bacterial infection is suspected, appropriate antimicrobial treatment may be considered.
• Infection control
  • Suspected or confirmed patients should be reported to public health authorities and managed with isolation and standard, droplet, and aerosol (during procedures) infection-control precautions. Patient contacts should wear personal protective equipment (PPE).
• Precautions and risk of complications
  • Complications: severe pneumonia, ARDS, pulmonary fibrosis, secondary bacterial pneumonia, sepsis, and multiorgan failure.
  • High-risk groups (older adults, people with chronic diseases, pregnant women, and immunocompromised people) have an increased risk of severe disease.
  • Do not consume uncooked poultry or raw eggs; wash your hands and disinfect immediately after contact with items suspected of being contaminated.
  • Follow instructions related to public health measures (poultry culling, movement restrictions, etc.)

Checklist Before an Outpatient Visit (Including Recommended Items and Sample Questions)

• Recommended items to bring
  • A list of currently taken medications (including prescription drugs, over-the-counter medications, herbal medicines, and supplements)
  • Allergy history (especially allergies to medications and eggs)
  • Underlying diseases and medical history (asthma, COPD, heart disease, diabetes, chronic kidney failure, etc.)
  • Recent travel history and contact with birds (poultry): countries visited, dates, and exposure circumstances (participation in culling, visits to poultry farms, contact with wild birds, etc.)
  • Time of symptom onset and progression (fever, cough, shortness of breath, sputum, muscle aches, etc.)
  • Recently measured body temperature and, if possible, oxygen saturation (readings from a portable pulse oximeter, if available)
  • Whether you are pregnant (if applicable)
  • Recent vaccinations received (such as the seasonal influenza vaccine)
• Items healthcare professionals may ask about during an outpatient visit (organizing these in advance may be helpful)
  • Route of exposure (whether there was direct contact with poultry and whether there was contact with contaminated objects)
  • Factors associated with worsening symptoms (shortness of breath, changes in consciousness, persistent high fever, etc.)
• Self-preparation before visiting
  • If you have a fever or respiratory symptoms, put on a mask, contact the hospital, and confirm its instructions
  • If emergency symptoms (severe shortness of breath, persistent chest pain, decreased consciousness) occur, visit the emergency room immediately

General Sample Questions to Ask the Doctor

• "What are the expected effects and side effects of this medication (antiviral medication)?"
• "How serious are my symptoms? How likely is it that I will need hospitalization or intensive care?"
• "How should I receive treatment and isolate myself at home? What preventive measures should my family members or housemates take?"

Disease-Specific Sample Questions

• "I recently had contact with poultry suspected of being infected. Could you tell me whether I need prophylactic antiviral medication (preventive treatment)?"
• "I was exposed to poultry during pregnancy. What are the risks to me and the fetus, and what tests and treatments are recommended?"