Influenza, commonly known as the flu, is a highly contagious viral infection that primarily affects the respiratory system. It is caused by influenza viruses, which belong to the Orthomyxoviridae family. Influenza viruses can infect humans as well as various other animals, including birds and pigs.
Influenza typically occurs in seasonal outbreaks and can lead to a range of symptoms, including:
- Fever: A sudden and high fever is a common symptom of the flu.
- Cough: Influenza often leads to a persistent dry or productive cough.
- Sore Throat: A sore or scratchy throat is a frequent symptom.
- Muscle Aches: Pain and stiffness in the muscles, often referred to as myalgia, can be severe.
- Fatigue: Profound tiredness and weakness are typical during the flu.
- Headache: Intense headaches are common.
- Chills: Shivering and chills are often present, especially with a high fever.
- Nasal Congestion: A runny or stuffy nose may occur.
- Sneezing: Frequent sneezing can accompany the infection.
- Gastrointestinal Symptoms: Some people with influenza may experience symptoms like nausea, vomiting, and diarrhea, although these are more common in children.
Influenza can range from mild to severe, and it can lead to complications, especially in vulnerable populations like young children, the elderly, and individuals with weakened immune systems. Complications can include pneumonia, bronchitis, sinus infections, and exacerbation of underlying health conditions.
Influenza viruses are classified into three main types: A, B, and C, with types A and B being the most significant concerning human illness. Influenza A viruses are further categorized into subtypes based on the surface proteins hemagglutinin (H) and neuraminidase (N). These subtypes can mutate, leading to new strains of influenza, which is why flu vaccines need to be updated regularly to provide protection against the most prevalent strains.
Vaccination is a crucial strategy for preventing the flu. The annual flu vaccine is designed to offer protection against the specific influenza strains that are expected to be most common during the upcoming flu season. Other preventive measures include good hand hygiene, avoiding close contact with infected individuals, and staying home when you are sick to prevent the spread of the virus.
Influenza is highly contagious, and it can spread through respiratory droplets produced when an infected person coughs or sneezes. It is also possible to contract the virus by touching contaminated surfaces and then touching your face. If you suspect you have the flu, it is important to seek medical advice, especially if you are at higher risk for complications or if your symptoms are severe. Antiviral medications may be prescribed by a healthcare professional to reduce the severity and duration of the illness.