Flu Symptoms and Their Biological Basis

Also known as Influenza, flu is a contagious respiratory illness that occurs due to influenza viruses. It is often self-diagnosable but sometimes, it becomes severe due to negligence and at times, can lead to death. Flu characteristics affect our body as it attacks the nose, lungs and throat of a person. The categories of people who are at highest risk to attain the flu are pregnant women, older people, young children and people having chronic diseases and weaker immune systems.

In this article we will go through all possible flu causes, symptoms, diagnosis and complications related to it. Also, we will know about the difference between cold and flu since many people get confused with both the terms. It will be easier for them to distinguish between cold and flu after understanding the cold and flu characteristics, severity of both and what is the level of seriousness of both.

Causes of Flu

The cause of flu is viruses and it is contagious, i.e. it spreads from one person to another through sneezing, coughing and transfer of droplets from the infected person. Flu can also spread with objects that are infected with the virus.

Symptoms of Flu

Flu seems to have the symptoms of the common cold such as chest cold or head cold, and are also caused by viruses like cold does. However, there are some differences in the way these symptoms occur in flu and cold. Some of the symptoms of the flu are mentioned as follows:

• Fever: It is a body temperature that is higher than a normal temperature (around 98.6 F). It varies from person to person, and fever is not a disease. It is a sign that your body is trying to fight off an illness or infection. 

• Headache: It is a pain arising from the head/upper neck of the body. It can originate from the tissues and structures surrounding the skull or the brain.

• Chills: It refers to a feeling of being extremely cold without an apparent cause. When our muscles repeatedly expand/contract and the vessels in your skin get constricted. Chills cause you shiver or shake and also fever. 

• Muscle Soreness: It is a side effect of the stress put on muscles and flu onset can make you feel that your muscles are sore.

• Aches: It is a continuous or prolonged pain in a part of one's body which is not intense but dull.

• Fatigue, Weakness: It is an overall feeling of tiredness or no energy. When you're fatigued, you have no motivation and sleepiness may be its symptom. It is one of the flu characteristics to get weakness or fatigue.

• Sneezing: It is the body’s sudden response of removing irritants from your nose or throat. A powerful and involuntary expulsion of air is called sneezing and is part of our immune response. Sternutation is another term used for sneezing.

• Chest Discomfort: Also called Angina, it is a discomfort caused due to our heart muscle not getting enough oxygen-rich blood. It is the feeling of pressure or squeezing in your chest. The discomfort can also occur in our shoulders, arms, neck, jaw, or back.

• Coughing: It is a common reflex action that helps in clearing our throat of mucus or foreign irritants. A cough that lasts for less than three weeks is an acute cough.

• Stuffy Nose: It is the nasal congestion and can also be a symptom of another health problem like a sinus infection.

• Sore Throat: It occurs many times because of overuse of voice, very dry mouth or sleeping with the mouth open. It is a sign of little pain in the throat area.

• Loss of Appetite: Not wanting to eat, no desire for eating with the same intensity as before, unintentional weight loss, and not feeling hungry all come into this category. 

• Secondary Bacterial Infections: It may be caused by the first treatment or by alteration in the immune system. Two examples include a vaginal yeast infection after taking antibiotics for treating an infection caused by bacteria.

• Nausea: It is the sensation of a feeling of vomiting. It can be acute and short-lived/prolonged. 

• Vomiting: Expelling one’s ingested food and liquid out of the mouth and causing discomfort is the vomiting.

Colds generally have milder symptoms than flu and are not a threat to health whereas the flu may cause serious health problems. Flu symptoms are abrupt and can affect your day to day routine if not paid attention for the treatment. Cold is caused due to common viruses which are less risky whereas flu are caused by viruses that occur within a specific time period with its outbreak and its vaccination and cure can be difficult to find as these will be new to the environment. Examples of flu are Swine flu (Avian influenza H1N1), seasonal influenza A (H3N2), etc. The best way to prevent the flu is by getting a flu vaccine every year.