Influenza, commonly known as the flu
It primarily affects the nose, throat, and lungs and can range from mild to severe illness. In some cases, it can lead to serious complications or even death, especially in vulnerable populations.
Types of Influenza Viruses
- Influenza A:
- Found in humans and animals (e.g., birds, pigs).
- Causes most seasonal flu epidemics and pandemics.
- Subtypes are classified based on two surface proteins: Hemagglutinin (H) and Neuraminidase (N) (e.g., H1N1, H3N2).
- Influenza B:
- Found only in humans.
- Causes seasonal outbreaks but less severe than Influenza A.
- Influenza C:
- Milder illness compared to A and B.
- Rarely causes epidemics.
- Influenza D:
- Primarily affects cattle and not known to infect humans.
Symptoms
Symptoms of influenza typically appear 1–4 days after infection and can last for 5–7 days or longer.
Common Symptoms:
- Fever or chills
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headache
- Fatigue
- Vomiting or diarrhea (more common in children)
Severe Symptoms:
- Difficulty breathing
- Persistent chest pain
- Confusion or dizziness
- Severe dehydration
- High fever that does not improve
