How Influenza A Kills People? Complications and Warning Signs

According to the Centers for Disease Control and Prevention (CDC) Influenza causes more hospitalizations among young children than any other vaccine-preventable disease. According to the CDC, the single best way to protect against seasonal flu and its potential severe complications is for children to get a seasonal influenza vaccine each year. Flu vaccination is recommended for all children aged 6 months and older. Also, making healthy choices at school and at home can help prevent the flu and spreading flu to others (see Here’s How the CDC Recommends Schools Clean and Disinfect to Help Slow the Spread of Flu; But Know What You Should Do, Too ).

The influenza virus can directly lead to death if the symptoms of the infection cause serious breathing problems or severe dehydration. However, the more common causes of death are secondary infections, such as bacterial pneumonia, and sepsis when harmful organisms that overtake the blood or other tissues, cause a harmful immune reaction that leads to organ failure and septic shock.

Influenza A can also infrequently lead to encephalitis (inflammation of the brain), myocarditis (inflammation of the heart), myoglobinuria (a condition of oxygen-binding muscle protein discovered in urine) and renal failure (kidney failure).

Encephalitis can cause seizures and dangerous swelling of the brain. Myocarditis can cause heart failure or sudden death.

Reye syndrome is a rare but potentially fatal condition characterized by encephalopathy (brain disorder); fatty liver; elevation of liver enzymes, elevation of ammonia, or elevation of both; hypoglycemia; and lipidemia. Reye syndrome, although rare, occurs rapidly during epidemics and following an infection of influenza A or influenza B. Reye syndrome is higher risk among children who are sick and have ingested aspirin.

A number of flu tests are available to detect influenza viruses in respiratory specimens. All of these tests require that a health care provider swipe the inside of your nose or the back of your throat with a swab and then send the swab for testing. The most common tests are called “rapid influenza diagnostic tests (RIDTs).” RIDTs work by detecting the parts of the virus (antigens) that stimulate an immune response. These tests can provide results within approximately 10-15 minutes, but are not as accurate as other flu tests (ie., False Negative results possible). A sick patient could have Influenza A, even though the rapid test (RIDT) result is negative.

Other flu tests are called “rapid molecular assays” that detect genetic material of the virus. Rapid molecular assays produce results in 15-20 minutes and are more accurate than RIDTs. In addition, there are several more-accurate and sensitive flu tests available that must be performed in specialized laboratories, such as those found in hospitals or state public health laboratories. Results may take one hour or several hours.



The incubation period for influenza ranges from 1 to 4 days with an average of about 48 hours.

Symptoms similar to the common cold start the flu starts with a sore throat, runny nose and eye irritation. These symptoms are likely to mark the beginning of the illness, but there may be a few signals that the illness is more than a common cold. A low grade temperature might be one of those signals. There might be a temporary burning in the chest that goes away.

Next, influenza involves sudden onset of chills, fever, weakness and fatigue, cough, and generalized aches and pains (especially in the back and legs). A headache usually develops, often with photophobia (an aversion to bright lights) and retrobulbar aching (headache-like pain behind the eyes, especially when the patient tests the range of motion of eyeballs and field of vision). Respiratory symptoms gradually develop with the return of burning in the chest or “substernal burning.” Initially, the cough is non-productive and dry. Runny nose and stuffiness increases. Later, lower respiratory tract illness becomes dominant with a persistent cough that is productive (produces phlegm).

Many people think that gastrointestinal symptoms are not associated with Influenza A, but vomiting and diarrhea are possible, especially among younger children.


Bacterial pneumonia (secondary bacterial pneumonia) is the most common flu complication that leads to death. Influenza A can damage the lungs and cause vulnerability to a bacterial infection. The warning signs are a worsening cough, bloody sputum, dyspnea (difficult breathing), and rales (noises “crackles” doctors listen for when using a stethoscope over the lungs). Secondary bacterial pneumonia is suggested by persistence or recurrence of fever and cough after the primary illness appears to be resolving. The impaired lung function with pneumonia can cause dangerously low oxygen levels, which can eventually cause problems with other organ systems and physiology of the body.

Sepsis occurs when infections get out of control, and the normal balance checks and controls of physiology in the body malfunction. The body’s abnormal immune response to the infection actually causes more damage than help. Sepsis becomes severe when blood pressure declines and insufficient blood flow causes organ failure and multiple organ failure. The severe condition is called Septic Shock. The risk of death is high with a diagnosis of Septic Shock, which requires admission to an Intensive Care Unit.

When to seek emergency medical attention for Influenza A
Children, teens or adults with any of the following symptoms should get medical treatment right away.

Rapid breathing or difficult breathing
Bluish skin color, lips or face
Ribs pulling in with each breath
Chest pain
Severe muscle pain (child refuses to walk)
Not drinking enough fluids
Altered consciousness — not waking up or not interacting
Fever above 104°F
Any fever in children less than 12 weeks
Being so irritable that the child does not want to be held
Fever or cough that improve but then return or worsen
Flu-like symptoms improve, but then return with fever and worse cough
Worsening of pre-existing chronic medical conditions
Fever with a rash
Being unable to eat (especially infants)
Dehydration (no urine for 8 hours, dry mouth, no tears when crying)
Having no tears with crying (especially infants)

Teens and adults should also beware of …
Difficult breathing
Shortness of breath
Persistent pain or pressure in the chest or abdomen
Persistent dizziness, confusion, inability to arouse
Sudden dizziness
Severe or persistent vomiting
Not urinating
Severe muscle pain
Severe weakness or unsteadiness
Fever or cough that improve but then return or worsen
Worsening of pre-existing chronic medical conditions


A young child who develops flu-like symptoms, such as fever, body aches and fatigue, should see a pediatrician to see if an antiviral medication such as Tamiflu (also available as generic oseltamivir), Relenza or Rapivab is needed.

Steps the CDC recommends to prevent flu include:

Avoid close contact with others, including hugging, kissing, or shaking hands.

Move away from people before coughing or sneezing.

Wash your hands frequently, especially after coughing, sneezing, or blowing your nose.

Cough and sneeze into a tissue then throw it away, or cough and sneeze into your upper shirt sleeve, completely covering your mouth and nose.

Disinfect frequently touched surfaces and objects such as toys and doorknobs.


CARDINAL NEWS | Here’s How the CDC Recommends Schools Clean and Disinfect to Help Slow the Spread of Flu; But Know What You Should Do, Too

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