What is flu

Overview

Influenza, commonly called the flu, is a contagious respiratory illness caused by influenza viruses. Unlike the common cold, the flu typically develops suddenly and can be more severe. The illness spreads easily from person to person through respiratory droplets released when an infected person coughs, sneezes, or talks.

Transmission and Spread

The flu spreads primarily through respiratory droplets, which can travel up to 6 feet from an infected person. People can also contract the flu by touching surfaces contaminated with the virus and then touching their face. The incubation period—the time between exposure and symptom onset—is typically 1-4 days, though some people develop symptoms more slowly. People are most contagious from one day before symptoms appear through 5-7 days after onset.

Symptoms and Severity

Common flu symptoms include:

• High fever (usually 101-104°F)
• Persistent cough and sore throat
• Body aches and muscle pain
• Fatigue and headaches
• Sometimes nausea, vomiting, or diarrhea (more common in children)

Types of Influenza

Three main types of influenza viruses affect humans: Type A is the most common and causes seasonal epidemics; Type B is milder but can still cause significant illness; Type C is rare and typically causes mild illness. Influenza viruses constantly mutate, which is why immunity from previous infections or vaccines may not protect against new strains.

Prevention and Treatment

The flu vaccine is the most effective prevention method, available in multiple formulations. Annual vaccination is recommended, especially for high-risk groups like elderly individuals, young children, and people with chronic conditions. Treatment focuses on rest, hydration, and managing symptoms. Antiviral medications like oseltamivir can reduce symptom duration if taken early. Most people recover without specific treatment.