Commonly known as flu, is a highly contagious respiratory illness caused by influenza viruses. The flu can affect people of all age and can cause mild to severe illness, and in some cases can lead to death.

Symptoms typically include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. People may also experience vomiting and diarrhoea, more common in children than adults.

Flu primarily spread through droplets from coughs or sneezes, by touching contaminated surface touching mouth, nose or eyes. Best way to prevent flu is by getting flu vaccine each year, practicing good hand hygiene, using mask sanitizer, avoid contact with sick people.

Treatment typically involves rest, fluid and over the counter medications to relieve symptoms. Antiviral medications may also be prescribed in some cases flu can be serious in young children, older adults and people with certain underline medical conditions. If you develop flu like symptoms stay home and avoid contact with others to prevent spread of viruses.

                         TYPES OF INFLUENZA

They are of three types that cause human influenza Type A, Type B and Type C.

1. Influenza A- This is the most common type of influenza virus that cause seasonal flu epidemics. Influenza A viruses are further classified based on their surface proteins, hemagglutinin(H) and Neuraminidase(N), into different subtypes. Some of subtypes of influenza A viruses that have caused pandemics in the past include H1N1, H2N2, H3N2.
2.  Influenza B-This type of influenza virus is less common than influenza A but still causes seasonal flu epidemics. Unlike influenza A, there are on subtype of influenza B viruses.
3. Influenza C- This type of influenza virus is less severe than types A and B and generally cause mild respiratory illness. Influenza C viruses do not cause epidemics or pandemics and are not included in seasonal flu vaccine.

Within each types of influenza virus, there  are many different strains or subtypes that can cause illness. These strains can vary from year to year, which is why a new flu vaccine is developed each year to protect against the most common strains expected to circulate during flu seasons.

                  VARIENTS OF INFLUENZA

Influenza viruses are known for their ability to multiply rapidly, and this can lead to the emergence of new variants or strains of the virus. Here are some of the variants of influenza that have been identified.

1-Antigenic drift variants-

These are minor changes that occur in the surface proteins of influenza viruses over time. These changes can lead to new strains of the virus that are slightly different from previous strains, and this can make it more difficult for the body to recognize and fight off the virus.

2-Antigenic shift variants- These are major changes that occur when two different strains of influenza virus infect the same call and exchange genetic material. This can result in the emergence of a new strain of the virus that is very different from previous strains and this can lead to a pandemic if the new strain is able to spread easily from person to person.

3-Avian influenza- Avian influenza also known as bird flu, is caused by influenza viruses that  primarily affect birds. In rare cases, these viruses can infect humans , and this can lead to severe illness or death. Avian flu that has caused concern in recent years is H5N1 strain.

4-Swine influenza- Swine influenza also known as pig flu, is caused by influenza viruses that primarily affect pigs. Like avian influenza, these virus can occasionally infect humans, and this can lead to illness. Swine influenza that has caused concern in recent years is H1N1 strain.

Variants of influenza can cause concern, most cases of seasonal flu are caused by the standard strains of influenza A and B that circulate each year . vaccination remains the best way to prevent the flu and its complications.