What Causes Influenza?


Influenza, commonly known as the flu, is caused by the influenza virus. It’s a contagious respiratory illness that can affect the nose, throat, and sometimes the lungs. The influenza virus is classified into different types and subtypes, which can vary in their severity and the strains they produce. The main types of influenza viruses that cause human infections are influenza A, B, and C.

Influenza A and B viruses are responsible for seasonal flu outbreaks, while influenza C viruses generally cause milder respiratory symptoms. Influenza A viruses are further categorized into different subtypes based on two surface proteins: hemagglutinin (H) and neuraminidase (N). These proteins have different variations, and the combination of specific H and N variations determines the subtype of the virus. This is why you often hear about influenza strains like H1N1 or H3N2.

Influenza viruses are highly contagious and spread through respiratory droplets that are produced when an infected person coughs, sneezes, or talks. People can also become infected by touching a surface or object that has the virus on it and then touching their mouth, nose, or eyes. The virus can survive on surfaces for a period of time, making it important to practice good hygiene, such as regular handwashing and avoiding close contact with sick individuals.

Influenza viruses can mutate over time, leading to the emergence of new strains. This is why the flu vaccine needs to be updated annually to target the most prevalent and virulent strains expected for that flu season. The symptoms of influenza can include fever, chills, cough, sore throat, body aches, fatigue, and sometimes respiratory issues. In severe cases, influenza can lead to complications like pneumonia, especially in vulnerable populations such as the elderly, young children, and individuals with certain medical conditions.

Vaccination is a key preventive measure against influenza. The flu vaccine stimulates the immune system to produce antibodies that can protect against the specific strains of influenza included in the vaccine. While the flu vaccine may not offer complete protection against all strains, it can significantly reduce the risk of severe illness and complications associated with influenza.