Dangerous complications of seasonal flu

Seasonal flu is an acute respiratory infectious disease caused by Influenza virus that infects the nose, throat and lungs. In Vietnam, seasonal flu usually circulates year-round, but tends to concentrate in winter and spring. The peak of flu season can fall around February - April and September - October every year.

After Taiwanese (Chinese) star Barbie Hsu died in Japan from influenza and pneumonia, attention to influenza has skyrocketed. So what complications does seasonal flu cause and how dangerous is it?

Who is susceptible to complications?

Anyone can get seasonal flu, even healthy people with no history of chronic diseases.

Serious complications caused by seasonal flu can also occur in all subjects from children to adults and these complications are more likely to occur, causing more serious conditions in infants and children under 2 years old; the elderly over 65 years old; subjects with chronic diseases such as cardiovascular disease, diabetes, asthma... or with weakened immune systems such as patients taking immunosuppressive drugs, pregnant women...

Common complications of seasonal flu

Most people with seasonal flu will recover in a few days to less than 2 weeks, but some people will develop complications from the flu. These complications can be life-threatening and lead to death.

Sinus and ear infections

Sinus and ear infections can occur when the flu virus takes advantage of a weakened immune system to attack the cells lining the nose. Sinus infections cause noticeable symptoms such as a runny nose, nasal congestion, yellow or green nasal discharge, cough, and discomfort in the lower face.

In addition, the ear is connected to the throat through the eustachian tube, so when the flu virus attacks the mucosal cells, ear infections will also occur and are common in children, because the eustachian tube of children is shorter than that of adults and when inflamed, the eustachian tube cannot drain the virus-containing fluid effectively. This leads to symptoms such as earache, temporary hearing loss and loss of balance.

Bronchitis

The influenza virus enters the body through the mouth or nose and infects the upper respiratory tract of the nasal cavity, sinuses, throat and larynx. But when it can spread to the respiratory tract leading to the lungs, trachea and bronchi, it creates the premise for bronchitis.

When experiencing complications of bronchitis caused by the flu virus, the patient will experience unusual symptoms such as coughing up mucus, difficulty breathing and wheezing. Cough caused by bronchitis is often severe and persistent for up to 3 weeks.

Pneumonia

Influenza viruses can cause secondary infections such as pneumonia. Pneumonia occurs when the body's immune system is weakened, allowing the influenza virus to quickly spread deeper into the patient's airways, causing a lung infection, which causes the lungs to become infected, inflaming the air sacs in the lungs and causing these air sacs to fill with fluid.

Symptoms of pneumonia may include coughing up yellow or green mucus, high fever, chest pain when coughing or breathing, fatigue, difficulty breathing (sometimes requiring breathing support through a ventilator), fluid buildup around the lungs, or abscesses in the lungs. The respiratory symptoms characteristic of pneumonia may also be accompanied by nausea and/or diarrhea in some people.

In addition, mild pneumonia symptoms are almost indistinguishable from those of the common flu.

Myocarditis

When influenza viruses enter the body, they can directly attack the heart muscle, causing inflammation and death of heart muscle cells within a few hours. At this time, complications may not manifest as typical symptoms but develop silently, until the complications become serious, causing heart muscle hypertrophy.

In many cases, myocarditis will manifest through typical symptoms such as high fever, muscle fatigue, headache, watery eyes, runny nose, diarrhea, loss of appetite and difficulty breathing. After 1-2 days, difficulty breathing will increase along with more unusual symptoms in the chest area such as palpitations, chest pain and pain in the liver area.

In some individuals, influenza-induced myocarditis can cause severe symptoms such as pale skin, rapid, weak pulse, cardiogenic shock, and rapidly falling or undetectable blood pressure. These symptoms will worsen over time and quickly lead to death if the patient does not receive timely treatment.

Encephalitis

In rare but severe cases, the flu virus can cause encephalitis, which can affect a person's cognitive abilities through symptoms such as poor alertness, difficulty concentrating, memory loss, and even loss of control of certain muscles, leading to seizures. Sometimes, these complications can lead to permanent brain damage and disability.

Children and those with underlying chronic neurological conditions such as epilepsy and cerebral palsy tend to be most vulnerable to complications of encephalitis caused by seasonal flu. However, encephalitis is a very rare neurological complication.

Myositis, rhabdomyolysis

The influenza virus attacks the heart muscle, causing the heart muscle to lose its ability to circulate blood to organs, including skeletal muscles, causing acute ischemia of skeletal muscles, leading to complications of myositis and rhabdomyolysis. These complications cause the patient to suffer from metabolic acidosis, electrolyte disturbances, acute renal failure, and hypovolemic shock.

Myositis and rhabdomyolysis caused by seasonal flu often appear with symptoms such as pale skin, panic, lethargy followed by coma, rapid deep breathing, gradually decreasing blood pressure, rapid pulse, little urine and anuria after a few days, dark urine and gradually changing to an abnormal color.

Multiple organ failure

After entering the body, the influenza virus can directly attack heart muscle cells, killing these cells, causing inflammation, causing the heart to lose its ability to circulate blood to other parts of the body such as the liver, kidneys, brain, etc., thereby causing multiple organ failure and a high risk of death.

This complication damages and impairs the function of many organs of the body, especially the central nervous system and cardiovascular system, causing the patient to have impaired consciousness, the appearance of false circulating neurotransmitters, peripheral neuritis, reduced metabolism of vasoactive substances, increased capillary permeability, reduced lung expansion and blood oxygen.

Sepsis

Sepsis occurs when a previous infection spreads throughout the body. This is a complication that brings with it extreme symptoms of the body's response to infectious agents, with a high risk of threatening the patient's life.

This complication usually begins with the lungs, followed by the urinary tract, skin, and gastrointestinal tract. If not detected and treated early, sepsis can quickly cause tissue damage, severe organ failure, and death.

Symptoms of sepsis complications caused by seasonal flu include weak pulse or abnormally high heart rate; impaired sense of orientation; severe body aches and pains; high fever, shaking or chills; shortness of breath, hoarseness; continuous cold sweats…

Chronic condition worsens

When the flu virus attacks and causes illness in the body, certain immune cells are activated to fight off and minimize the spread of the virus. This immune response may be effective, but it can worsen chronic conditions such as diabetes, asthma, and heart disease.