Influensan

Influensan, commonly referred to as the flu, is an infectious respiratory illness caused by the influenza viruses. The disease is primarily spread through respiratory droplets when an infected person coughs or sneezes, or by touching surfaces and then the mouth, nose, or eyes. Influenza viruses are categorized into types A and B, which cause seasonal epidemics, and type C, which typically causes milder disease.

Symptoms usually begin suddenly and include fever or chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue. Some people, especially children, may experience vomiting and diarrhea. Most infections are self-limited, but the disease can be severe or fatal in young children, older adults, pregnant people, and those with certain chronic illnesses.

Diagnosis is based on clinical presentation and can be confirmed with laboratory tests, such as rapid influenza diagnostic tests or molecular assays (PCR). In severe cases or high-risk patients, antiviral medications (e.g., oseltamivir, baloxavir) are most effective when started early, typically within 48 hours of symptom onset.

Prevention relies primarily on annual vaccination, which targets circulating strains and is updated yearly. Other measures include good hygiene, respiratory etiquette, and staying home when ill. Public health surveillance monitors circulating strains to inform vaccine composition and outbreak response. Seasonality varies by region, with temperate zones experiencing winter peaks and tropical regions showing year-round activity.

Historical impact is significant, with influenza pandemics occurring periodically (notably in 1918, 1957, 1968, and 2009). Ongoing research focuses on vaccine effectiveness, antiviral resistance, and universal vaccines that provide broader protection against influenza viruses.