Swine flu

Disease Description (Causes and Symptoms)

• Definition summary: An acute respiratory illness caused by infection with the novel H1N1 strain of influenza A virus (originating from the 2009 pandemic). It is primarily transmitted through respiratory droplets and contact with contaminated surfaces.
• Causes and pathophysiology: Viruses released in the respiratory secretions (coughing and sneezing) of infected people enter the respiratory tract and infect the mucous membranes of the upper and lower respiratory tract. In some cases, lower respiratory tract involvement can cause severe complications such as pneumonia.
• Main symptoms: Sudden fever (usually 38℃ or higher), cough (generally dry cough), sore throat, muscle aches, headache, chills, and fatigue. Some patients may also have gastrointestinal symptoms such as diarrhea and vomiting. Symptoms usually appear 1–7 days after exposure (most often within 3 days).

Treatment Methods and Precautions

• Basic principles: Relieve symptoms and prevent complications. Antiviral treatment may be considered for high-risk individuals or those with moderate or more severe symptoms.
• Antiviral medications: Oseltamivir (oral) and zanamivir (inhaled) are representative options. They are more effective when started as soon as possible (within 48 hours after symptom onset), and the dose and duration are determined based on the doctor’s judgment (generally, a 5-day treatment is often the standard). For patients at high risk of severe disease (including pregnant women, infants and young children, and people with chronic diseases), antiviral treatment may be considered even if more than 48 hours have passed since symptom onset.
• Supportive treatment: Control symptoms with adequate fluid intake, rest, and fever and pain relief (e.g., acetaminophen). If vomiting or diarrhea is severe, monitor for dehydration and provide replacement fluids if necessary.
• Hospitalization and intensive care: In cases of hypoxemia, suspected pneumonia, rapid deterioration, or worsening underlying cardiopulmonary disease, hospital admission may be required, along with oxygen therapy, mechanical ventilation, intravenous antiviral medication, or antibiotics (in cases of secondary bacterial infection).
• Precautions (self-care)
  • Isolation and respiratory etiquette: Wear a mask, cover coughs and sneezes with a tissue and dispose of it, and wash your hands frequently.
  • Children and adolescents: Do not use aspirin (risk of Reye syndrome). Manage symptoms with fever-reducing medication and adequate fluids.
  • Pregnant women, people with chronic diseases, and older adults: If symptoms occur, seek medical attention promptly and ask about the possibility of antiviral treatment.
• Complications: Viral or secondary bacterial pneumonia, acute respiratory distress syndrome (ARDS), myocarditis, encephalitis, worsening of chronic diseases, and severe bacterial infections.
• Prognosis: Most people improve within several days to 1 week, but high-risk individuals may progress to severe disease or death. Children may remain contagious for a longer period than adults (up to 10 days or more).

Checklist Before an Outpatient Visit (Including Preparation and Example Questions)

• Items to prepare (recommended)
  • A record of the symptom onset date and symptom progression (fever, cough, shortness of breath, diarrhea, etc.)
  • Recent temperature records (fever pattern)
  • A list of medications currently being taken (including prescription drugs, over-the-counter medications, and supplements)
  • Medical history: chronic diseases (asthma, COPD, heart disease, diabetes, immunosuppression, etc.) and pregnancy status
  • Recent test results (if available) and vaccination history (whether you recently received an influenza vaccine)
  • Exposure information (whether you had contact with a confirmed case or were exposed in a group setting)
• Information that is helpful to provide directly to the doctor during the outpatient visit
  • The date symptoms began and when symptoms worsened
  • Information about recent overseas travel or association with an outbreak
  • Whether shortness of breath, chest pain, or decreased consciousness is present
• Self-check items before an outpatient visit
  • Check for shortness of breath (during exercise or at rest), changes in consciousness, decreased urine output (dehydration), and blood oxygen saturation (if available)

Examples of General Questions to Ask the Doctor

• Should I use an antiviral medication (oseltamivir or zanamivir) in this situation? When should I start it, and how long should I take it?
• What are the criteria for determining whether I am at high risk of complications? Do I need hospitalization or additional tests (such as a chest X-ray or oxygen measurement)?
• What self-care methods can I use at home (such as fever-reducing medication, fluid replacement, and the isolation period)?
• Management of contacts and family members: How long should I remain isolated at home? Do my family members need vaccination or preventive treatment?

Examples of Disease-Specific Questions

• Questions for pregnant women: I am pregnant—is it safe to take antiviral medication? How much risk does the infection pose to the fetus?
• Questions about children/school: When can a child who has been infected return to daycare or school? What information should be provided when notifying the childcare facility or school?