The influenza virus adversely affects the upper airways and lungs. Generally called "the flu" , the virus is usually passed from person to person. When a person who is infected with the influenza sneezes or coughs, the virus is passed through the air to an uninfected person via tiny droplets of virus infected saliva. Skin on skin contact can also transfer the virus.
The flu virus is characterized by an elevated temperature that onsets rapidly followed by aches and pains all through the body. Other symptoms can include a decrease in appetite, nausea, and extreme fatigue and lethargy. Sneezing and coughing may also be present.
The subject may also have difficulty getting to sleep and will generally feels sweaty and feverish. A blocked and/or runny nose is another common symptom of the virus. It typically takes about two days for the symptoms to appear after the person has been infected. The sufferer will continue to be infectious for at least five days after the first symptoms appear.
Influenza is often mistaken for the common cold, but it affects the lungs much more than a cold. People with a weak immune system are very susceptible to influenza, as are the elderly and young children. The virus is generally spread in the course of the winter months.
The influenza virus is classified into three categories or types - A, B, and C. Type A is the most serious and usually appears approximately every two to three years. This type is prone to mutation and repeatedly produces strains which people have no resistance against. Type A has been the cause of many epidemics and has been responsible for some pandemics where entire continents have been affected.
Type B influenza virus strain is responsible for lesser outbreaks of the infection. Those that have been infected with type B once will have an immune system that can successfully resist this type of virus for numerous years. Type B generally infects children aged from about 5 to 14 who have not been infected previously.
Type C influenza virus is the mildest strain of the infection. The symptoms of type C are comparable to symptoms associated with the common cold. The influenza virus is typically treated with bed-rest and keeping up an intake of fluids. If a patient's immune system is weakened doctors may prescribe anti-viral medications to assist in fighting the virus.