What is the Flu (Influenza)?

Influenza, commonly called the flu, is a pulmonary condition caused by the influenza virus. While the influenza virus can impact anyone, some populations, including children who are younger, adults who are older, and anyone with a reduced immune system, are more vulnerable to its harmful effects. The virus exhibits a high degree of contagiousness, spreading from an individual carrying the infection when they cough, sneeze, or engage in conversation near another person.

The flu can also be transmitted by touching contaminated surfaces and subsequently touching your nose, mouth, or eyes. Your doctor might call this condition influenza A or B. Symptoms can be mild to severe. Symptoms include body aches, fever, tiredness, sore throat, chills, and cough. Although most people recover within a couple of weeks, the flu can lead to severe complications like pneumonia, bronchitis, and sinus or ear infections in some cases. Prevention measures such as getting an annual flu vaccine, maintaining good hand hygiene, and avoiding contact with sick individuals can help reduce the risk of contracting the flu. If you have flu-like symptoms, staying at home and avoiding close contact with others is crucial to prevent the spread of the virus.

Signs and Symptoms

Flu symptoms typically manifest rapidly following infection, with most people experiencing a sudden onset of symptoms. The duration of these symptoms of the flu generally lasts for about one to two weeks. It is important to note that the flu is a highly contagious illness, capable of infecting many individuals within a relatively short timeframe. 

The following list outlines common signs of the flu:

• Fever
• Eye pain
• Widespread pain
• Chills
• Unsteadiness
• Lightheadedness
• Flushed face
• Headache
• Fatigue
• Upset stomach
• Nausea
• Vomiting
• Dry cough
• Trouble breathing
• Nasal discharge
• Sneezing
• Inflamed throat

Diagnosis

Healthcare providers can often diagnose the flu simply by evaluating the patient's symptoms, such as fever, chills, body aches, and respiratory issues. However, in certain situations, doctors may opt for a more definitive diagnostic tool like the polymerase chain reaction (PCR) test. This exam reveals the existence of the virus and provides a more accurate diagnosis of the flu.

Causes

The primary causes of the flu are influenza viruses that spread from person to person. These viruses travel through the air in droplets when an infected individual talks, coughs, or sneezes, making it easy for others to inhale these droplets and become infected themselves. The flu is highly contagious, and several strains of the virus exist, with new ones emerging regularly.

People with the flu are typically contagious for about a week, although this period may be longer for children and those with weakened immune systems. It is important to note that the strains of influenza virus change frequently, which is why flu vaccines are updated each year. In this way, the specific causes of influenza change slightly. Consequently, antibodies from previous influenza infections may not offer protection against new strains. You may need to get yearly vaccinations to reduce the risk of contracting the flu.

Risk Factors

The flu can sometimes lead to severe illness and complications, particularly in individuals with specific risk factors or pre-existing medical conditions. In some cases, the flu can exacerbate these conditions, making them worse and causing additional health problems.

Risk factors for flu include:

• Age groups—Infants under 2 years old and seniors above 65 years of age are more prone to complications.
• Accommodation— If you live in certain types of housing, such as a nursing home, you may be at great risk.
• Pregnancy status—Those who are pregnant or planning a pregnancy during flu season are more susceptible to complications.
• Immune system strength—Individuals with compromised immune systems, such as cancer patients or those on immunosuppressive medications, have an elevated risk.
• Ethnic background—American Indians and Alaska Natives may experience a higher likelihood of flu-related complications.
• Pre-existing health conditions— Health conditions such as disease of the kidney, liver, or heart can heighten the likelihood of flu-related complications.
• Body weight—Those with a 40 or higher body mass index (BMI) may experience intensified symptoms and an increased probability of complications.

Prevention

Flu prevention is essential for staying healthy. You can take several measures to avoid catching the flu and minimize its spread. 

The following methods for how to prevent flu can help protect yourself and others:

• Get vaccinated
• Frequent hand washing
• Use hand sanitizer
• Keep surfaces clean
• Strengthen your immune system

You can also avoid close contact with sick individuals and cover your mouth and nose when coughing or sneezing.

Prognosis

Each year, millions of people in the United States contract the flu. The majority of individuals recover within one to two weeks. Some individuals may develop more severe complications such as pneumonia or brain infections. Thousands of these severe cases require hospitalization. Approximately 36,000 individuals in the United States pass away each year because of complications linked to the flu.

Treatment

There are several at-home treatments for the flu. 

Flu treatments include:

• Rest—Rest and stay hydrated to help your body fight off the virus.
• Pain medication—Take over-the-counter medications to reduce fever and relieve body aches. Consult your doctor if you belong to a vulnerable group like children or pregnant women.
• Antibiotics—Avoid antibiotics, as they are not effective against the flu virus.
• Antiviral medication—In some cases, antiviral medications prescribed by a healthcare provider may help shorten the duration and severity of the flu.
• Alternative methods—Use warm liquids and humidifiers as alternative remedies to provide comfort and symptom relief.

When managing flu symptoms and treatment, it is helpful to avoid certain actions that can worsen symptoms or pose risks to your health. 

Things to avoid:

• Mis-Medicating young children—Do not give aspirin to children under 12 years old. It can sometimes result in a serious condition called Reye's syndrome, which can have significant consequences.
• Smoking—Avoid smoking, as it can further irritate the respiratory system.
• Antibiotics—Avoid taking antibiotics, as they are not effective against viral infections like the flu.

The flu can sometimes lead to more severe complications, particularly for those with weakened immune systems or pre-existing health conditions. 

Possible flu complications include:

• Seizures—High fever and dehydration can cause seizures, especially in young children.
• Meningitis—The flu virus can cause inflammation of the membranes that protect the brain and spinal cord.
• Encephalitis—Rarely, the flu can cause inflammation of the brain itself. This is one of the serious complications of influenza.
• Pneumonia—A secondary bacterial infection may occur, leading to inflammation and infection of the lungs.