Overview and Statistical Facts
Influenza, commonly known as flu, refers to a respiratory infection caused by influenza viruses. These viruses are present in the air and infect a person by entering through nose or mouth. Flu can be serious or even fatal for newborn babies, elderly people and people suffering from chronic diseases. Gastroenteritis is commonly known as ‘Stomach flu’ or ’24-hour flu’ which is not caused by influenza viruses.
Flu and cold are both respiratory illnesses but are caused by different groups of organisms. Generally, flu is more severe than common cold. The symptoms of flu tend to start more suddenly, are more serious and can result in complicated health conditions, such as pneumonia, bacterial infections or hospitalizations.
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Flu and cold cannot be differentiated by analyzing the symptoms alone. These can be differentiated only through special tests performed a few days after the development of symptoms.
The incidence of flu is more common during winters. Due to this, it is known as ‘Seasonal flu.’ However, a person may catch flu at any time of the year.
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Hemophilus influenzae is the bacteria that causes lung infections in infants and children but does not cause flu.
Influenza is considered as one of the deadliest diseases of humans. In the U.S. alone, flu infection is known to claim about 36,000 lives every season, while the average cost of hospitalizations and outpatient doctor visits due to flu amounts to approximately 10 billion USD.
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According to the World Health Organization (WHO), influenza is responsible for nearly 500,000 annual deaths globally. There have been four major pandemics of flu since 1990 — The Spanish flu (1918-1919), the Asian flu (1957-1958), the Hong Kong flu (1968-1969) and the Swine flu (2009) — with Swine flu being the least deadly pandemic out of the four. The Spanish flu was responsible for about 100 million deaths. Not to forget the Recent Covid-19 Flu- which has put the world to halt and people are forced to stay at home. This Flu is caused by not the influenza virus but from a different type of virus.
Types and Symptoms of Flu
Types of Flu:
There are four types of influenza viruses, namely, A, B, C and D. Human influenza viruses, A and B cause seasonal flu every year. The emergence of a new strain of influenza virus are responsible for a pandemic. Influenza C viruses are not known to cause serious symptoms or result in epidemics. Influenza D viruses infect cattle and are not known to cause any illness in humans.
Influenza A viruses are divided into subtypes based on two proteins found on the surface of the virus, hemagglutinin (H) and neuraminidase (N). Influenza A virus can be classified into various strains, namely:
- H1N1, which caused the Spanish flu (1918) and Swine flu (2009)
- H2N2, which caused the Asian flu (1957)
- H3N2, which caused the Hong Kong flu (1968)
- H5N1, which caused Avian flu or Bird flu (2004)
- H7N7
- H1N2
- H9N2
- H7N2
- H7N3
- H10N7
- H7N9
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Influenza B viruses are not divided into subtypes, but can be categorized into lineages and strains. The currently circulating Influenza B virus lineages are: B/Yamagata and B/Victoria.
Influenza C viruses are less frequently detected and cause mild infections, which are not a threat to public health.
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Symptoms of Flu:
Following are the common symptoms of flu:
- Fever or feverish chills
- Dry cough
- Sore throat
- Runny or stuffy nose (sometimes)
- Muscle or body aches
- Headaches
- Fatigue
- Vomiting and diarrhea, which is more common in children than adults
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Most patients with flu recover within a few days, but some people develop complications. These include:
- Sinus and ear infections
- Pneumonia
- Inflammation of heart (myocarditis)
- Inflammation of brain (encephalitis)
- Inflammation of muscles (myositis)
- Multi-organ failure
- Sepsis
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Emergency warning signs of flu sickness include
In children:
- Fast or troubled breathing
- Bluish skin color
- No interactions
- extreme irritability
- Fever with a rash
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In infants:
- Unable to eat
- Troubled breathing
- No tears when crying
- Less frequent urination
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In adults:
- Difficulty breathing or shortness of breath
- Pain or pressure in chest
- Sudden dizziness
- Mental confusion
- Flu like symptoms that improve, but return with fever and cough
- Severe vomiting
Risk Factors of Flu
Following are the factors that increase the risk of developing flu or its complications:
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Age: Infants, children and elderly are more susceptible to catching flu.
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Weakened Immune System: People with compromised immune system such as those suffering from HIV infection or patients who are on immune suppressing agents, like those suffering from cancer, are at a higher risk of catching flu.
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Chronic Illness: Patients with chronic illness such as those suffering from asthma, diabetes, heart disease can increase the probability of catching flu.
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Pregnancy: Pregnant women are at a high risk of catching flu and developing complications especially in second and third trimester. Women are also susceptible to develop complications two weeks after giving birth.
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Obesity: Obesity increases the risk of developing complications due to flu.
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Occupational Hazards: Increased exposure to influenza virus occurs for people working in health care industry like doctors, nurses etc. They also become carriers of the virus and can spread the disease to otherwise healthy yet vulnerable people who come in their contact.
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Do I Have Flu?
If you have high fever along with chills, severe muscle aches, dry cough and headache, then there is a chance that you have flu. If these symptoms appear suddenly with a feeling of being tired, then you must visit your doctor and get yourself checked. There is a chance that these symptoms might be of common cold, but it is necessary to go for proper diagnosis.
Causes and Prevention of Flu
Causes of Flu:
Flu is caused when a healthy person comes in contact with the influenza virus present in millions of minute droplets that are released by an infected person when he sneezes, coughs or talks. These viruses remain active up to 24 hours. Anyone, who comes in contact with these viruses suspended in the air or those that land on inanimate objects can catch the flu.
A person can catch flu a number of times within the same season because the flu virus undergoes rapid mutation and changes its form. When a person catches flu for the first time, his body makes antibodies against that strain of virus. But, if the person encounters a different strain of flu virus in the same season itself, his body cannot protect him and develops flu again.
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Prevention of Flu:
Following measure should be taken to prevent catching flu:
- Regular cleaning of inanimate surfaces, such as telephone, doorknobs and computer keyboards
- Avoiding crammed and public places
- Getting flu vaccine
- Washing hands before touching eyes, nose or mouth
- Wearing masks
People, who are suffering from flu, should also take the following measures to avoid the spread of flu:
- Covering mouth and nose while sneezing or coughing
- Avoiding spitting
- Throwing away used tissue in bins
- Remaining at home when sick
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Vaccination against flu can be taken before the onset of the seasonal flu. These vaccines protect against three or four influenza viruses that are most likely to be the causative organisms during that season. Among healthy individuals, these vaccines protect against virus strains that are not present in the vaccines.
In the elderly, these vaccines are less effective in providing immunity, but they reduce the severity of disease and chances of developing complications. These vaccines are only available as injections. Nasal spray flu vaccines are no longer recommended by the U.S. Center for Disease Control (CDC) as their efficacy was not found to be significant. These vaccines are recommended for the following groups of people, namely:
- People above the age of 65 years
- Pregnant women
- Children and adults with compromised immune system
- Children and adults with chronic illnesses
These vaccines are especially important for people, who are at a high risk of developing the disease or those, who are taking care of the ones infected with flu.
Diagnosis and Tests of Flu
The patient undergoes a physical examination and is analyzed for signs and symptoms of influenza, such as fever, chills, muscle aches and dry cough.
There are a couple of tests available for flu diagnosis:
1) Rapid Influenza Diagnostic Tests (RITD)
In this test, the part of virus, which stimulates the immune system is identified. The results are usually made available in 10-15 minutes but are not extremely accurate.
2) Rapid Molecular Assays
In this test, the genetic material of the virus is identified.
However, these tests are not very accurate. A person with the symptoms of flu can still be diagnosed with the infection even when the test results are negative.
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Treatment and Care of Flu
Treatment of Flu:
The treatment for flu depends on symptoms. Following medications can be used for managing the symptoms of flu:
1) Decongestants
These help in clearing the nasal passageway by reducing swelling. However, these should not be used regularly as these have a tendency to rebound symptoms if used for a longer period of time and then, stopped. Decongestants should be avoided by patients, who have irregular heart rhythm, hypertension, glaucoma and so forth.
2) Antihistamines
Antihistamines are used to manage symptoms like runny nose, itchy and watery eyes, etc. Medicines that can be used include levocetirizine, diphenhydramine, fexofenadine and chlorpheniramine.
3) Antivirals
Antiviral drugs, such as oseltamivir and zanamivir are prescribed for patients, who are very sick, and for those, who have other chronic illnesses and are highly susceptible of developing complications due to flu.
These function by inhibiting multiplication of virus in the body. These medications do not cure flu, but help in reducing the length of illness and relieve symptoms. However, they are effective in preventing death in people hospitalized due to flu.
4) Antibiotics
These are not prescribed for treating flu as they are ineffective in treating viral infections. However, they can be used to cure any other symptom that arises due to the complications of flu.
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Care of Flu Patient:
A flu patient is advised to take proper rest and maximize his duration of indoor stay. He should avoid going in public places, which could otherwise spread his/her illness. Precautions must be taken while sneezing, coughing or disposing off used tissues.
Hands must be washed regularly to prevent spread of virus. Surfaces that are at a high risk of getting contaminated should be disinfected regularly. Patients should also keep a watch on their symptoms. If the symptoms worsen, medical attention should be sought immediately.
OTC Medication or Self-Management Methods for Flu
OTC Medication for Flu:
Following medicines are available as OTC medications:
1) Painkillers
Painkillers like acetaminophen (paracetamol), ibuprofen and naproxen can be used to manage headaches and muscle pains. Aspirin can also be used, but it suggested to be taken only under medical supervision by patients suffering from hypertension, cardiac diseases, peptic ulcer and blood coagulation disorders. Children should never be given aspirin for flu-like symptoms as it might cause Reye’s syndrome – a condition that results in brain and liver damage.
2) Cough Suppressants
Dry coughs can be managed by taking cough suppressants like dextromethorphan that help manage dry coughs without mucus.
3) Decongestants
Common decongestants that are available over the counter (OTC) are pseudoephedrine and phenylephrine.
4) Antihistamines
Antihistamines that can be used to manage not-so-common symptoms, such as runny nose and itchy eyes include diphenhydramine, cetirizine, loratadine, etc.
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Self-Management of Flu:
For self-managing flu, following steps could be taken:
- Increasing intake of fluids
- Gargling with warm salt water to relieve sore throat
- Avoiding alcohol
- Avoiding smoking
- Cooling pads to bring down fever
- Staying at home and taking plenty of rest
- Consuming healthy diet
Natural Ways to Treat Flu
Following methods can be used for treating flu at home:
1) Increased Uptake of Fluids: Increased uptake of fluids helps in flushing out toxins from the body, while keeping the body well hydrated, especially when the patient is experiencing vomiting and diarrhea. Not to be mentioned, alcohol consumption should be avoided.
Consumption of warm liquids, such as soups and tea help relieve sore throat and in the vapor form, these warm food help soothe the nasal passage. A study, published in the journal, Chest, indicates that consuming chicken soup actually helps improve symptoms of upper respiratory tract.
2) Humidification: Patient can consider taking a steamy shower several times a day or can inhale steam while sitting in the room using a vaporizer or humidifier to help ease nasal congestion, and pain due to sore throat.
3) Salt Water Nose Rinsing: This helps in easing nasal congestion and cleaning out viruses from the nose.
4) Menthol: Menthol can be used for clearing nasal passage as it has a strong smell, which can cut through blocked noses. It also helps in soothing the skin, which might have become tender due to increased nose blowing.
5) Vitamin C: Foods rich in vitamin C should be consumed during flu illness as it helps in strengthening the body’s immune system, and helps fight off the illness.
6) Ginger: Ginger is very effective in managing sinus symptoms and congestions.
7) Nettle Leaf: It is rich in vitamins and trace minerals, and helps remove toxins and allow the body to stay hydrated.
Health Tip by Experts
According to experts, flu can be prevented by getting vaccinated before the flu season begins, by following strict hygiene practices, such as regular washing of hands, cleaning surfaces, and avoiding crowded places. People, who still get infected, should take plenty of rest and avoid spreading the disease. If complications develop, medical help should be sought immediately.
