Flu is also known as influenza. It has a disease that is caused by viruses and is spread mainly through coughing and sneezing. Flu is caused by different viruses namely Type A influenza virus, Type B influenza virus, and Type C influenza virus. Influenza viruses are spread through droplets in the air which occur when one sneezes or coughs. One gets flu by inhaling the droplets containing the viruses. Flu can also be spread through touching surfaces contaminated by flu-causing viruses and then touching your nose with the same hand.

Flu can cause mild or serious illness and in some instances, it may be fatal. Young children, the elderly and people who have certain ailments are susceptible to severe flu illnesses. More than 200,000 people are hospitalised every year in the United States due to flu illnesses.

Flu season
Flu usually occurs all year round but there is a season when the number of flu infec-tions peaks. This season usually occurs in the second half of the cold in each hemi-sphere. In the United States, the flu season usually occurs in winter. The number of flu infections increases upto ten times or more. The Center For Disease Control (CDC) recommends that everyone aged 6 months and above should get vaccinated in order to prevent flu infection. CDC has found the flu vaccine to be 60% effective in helping prevent flu.

How flu starts
If you are experiencing symptoms and you are unsure as to whether you could be developing flu or just a common cold, you could establish whether a you may be coming down with flu by knowing how flu starts. Flu is usually characterised by the onset and development of the following symptoms:

Fatigue
Fatigue is a warning sign of flu. In fact, a sudden and excessive feeling of fatigue is a symptom that precedes all the other symptoms of flu. Fatigue is usually severe in a flu infection. It causes one to feel weak.

Fever
Fever is also one of the earliest signs of flu. It occurs upto temperatures of 100 de-grees Fahrenheit and beyond. Fever is usually a sign that one’s body is trying to fight off an infection. Flu viruses are unable to multiply in high temperatures. The body therefore raises its temperature as a defence mechanism against the flu viruses thus resulting into a fever. Fever may occur alongside chills in a case of flu infection.

Headache
Headache is a common symptom of flu. Headache during flu infection usually oc-curs as a result of the blood vessels dilating in the body’s attempt to raise its tem-perature so as to prevent the flu viruses from multiplying. Pressure inside one’s head increases as a result of the dilation leading to pain and a feeling of heaviness.

The headache in flu can also occur due to sinus pain. The mucus membranes along sinuses and nasal cavities can get inflamed leading to sinus pain.

Sore throat
A sore throat is a sign of flu infection. It causes a scratchy and uncomfortable feeling down one’s throat. Sore throat occurs as a result of the rapid multiplication of the flu viruses along the upper airways.

Muscles and joints aches
Muscles and joints pains usually occur in flu infection because of cytokinins which are produced as a result of the body’s immune system fighting the flu viruses. The cytokinins lead to the inflammation of muscles thus resulting into pain.

Coughs and runny nose
Coughing and a stuffy or runny nose are common symptoms of flu. They occur as a result of inflammation of the upper respiratory region.