What Is Influenza (Flu)?

Influenza is an RNA virus belonging to the Orthomyxoviridae family, which typically affects humans, birds, horses, pigs, and marine mammals. There are generally three different types of influenza viruses: A, B, and C. The ones commonly observed in humans are types A and B.

Influenza, commonly known as the flu, is a contagious respiratory infection. It usually appears seasonally and manifests itself with symptoms such as fever, chills, muscle aches, headaches, cough, sore throat, runny nose, fatigue, and overall body pains. These symptoms can vary from person to person and are often associated with the individual's immune system.

It can spread rapidly and may lead to severe complications, especially in the elderly, children, pregnant women, and those with weakened immune systems. Hence, taking preventive measures like vaccination plays a crucial role in preventing the spread of the disease.

What Is Influenza A?

This is the most common and severe type of influenza virus that can cause flu outbreaks in humans and animals. It can exist in different subtypes (e.g., H1N1 virus, H3N2 virus). These subtypes are named based on combinations of proteins on the virus's surface called hemagglutinin (H) and neuraminidase (N). The proteins on the surface of the influenza A virus can change over time, known as antigenic shift, which can make it challenging for the human immune system to defend against the virus.

Influenza A typically spreads through respiratory droplets and causes upper respiratory tract infections in humans, resulting in high fever, headaches, muscle and joint pains, cough, sore throat, runny nose, among other symptoms.

What Is Influenza B?

Influenza B is a virus that spreads from person to person, commonly seen in young children. It's generally less variable than influenza A. While influenza B doesn't have subtypes, it does have different variants.

Influenza B virus usually spreads through respiratory droplets when coughing, sneezing, or touching surfaces contaminated by an infected person. Symptoms often include fever, cough, sore throat, runny nose, muscle and joint aches, fatigue, similar to flu-like symptoms. While influenza B generally doesn’t cause as severe complications as influenza A, it can be severe, particularly in individuals with weakened immune systems or underlying health issues.

What Is Influenza C?

Influenza C is usually found in animals. Unlike influenza A and B, it's not included in common flu vaccines and typically doesn’t cause flu outbreaks.

Influenza Symptoms

The influenza virus spreads through droplets when an infected person coughs or sneezes. After settling into the respiratory system mucosa, it usually incubates for a period ranging from 1 to 7 days. Following this period, the disease causes infection in the upper respiratory tract, leading to the onset of initial symptoms related to the illness. Influenza symptoms can be observed similarly in individuals across almost all age groups.

Common symptoms of influenza include:

• Sudden onset of fever: High fever is one of the most prevalent symptoms of influenza. The fever can be 38°C or higher and can begin abruptly.
• Headache: Severe and continuous headaches are frequently observed among influenza symptoms.
• Muscle and joint pains: Widespread body aches, especially in the back, muscles, and joints, can be felt.
• Cough: A severe cough, dry or with phlegm, can occur and may persist for an extended period.
• Sore throat: Discomfort, pain, or sensitivity in the throat may occur, accompanied by difficulty swallowing.
• Runny or congested nose: Upper respiratory symptoms such as nasal congestion and less frequently, runny or postnasal drip may manifest.
• Fatigue and weakness: Influenza can reduce a person's energy levels, causing severe fatigue and weakness.
• Nausea and vomiting: Rarely, especially in children, nausea and vomiting might occur.

Diagnosing Influenza

During a medical examination, evaluation of symptoms such as fever, headaches, muscle and joint pains, cough, sore throat, runny nose, and fatigue, alongside a PCR test, can be conducted to diagnose influenza. However, antigen tests provide approximately 80-90% accuracy within a short time. These tests examine the genetic material of the influenza virus obtained from samples taken from the nose or throat. PCR testing helps conclusively determine the presence of the influenza virus. Additionally, for monitoring infection symptoms and a more detailed evaluation, a doctor might request a blood test.

Treating Influenza

Antiviral medications are prescribed for influenza treatment. These medications assist in reducing the duration, severity, and transmission of symptoms and complications caused by the influenza virus.

Treatment methods for viral infections like influenza and the flu are determined based on the severity of the illness and symptoms. Typically, alongside antiviral treatment, supportive measures are applied in influenza treatment. Doctors advise rest, ample fluid intake, and dietary recommendations. Additionally, supplements that boost the immune system, like Vitamin C, might be suggested.

Influenza Test

An influenza test is conducted to diagnose the presence or absence of influenza. Given the similarity in symptoms between influenza and Covid-19 viruses, an influenza test is one of the supportive tests used to make an accurate diagnosis and determine treatment.