It is an epidemic disease which poses a risk to the elderly, the weak, and people suffering from breathing difficulties.
There are three types of flu virus; A, B, and C. The most frequently, commonly occuring and the most severe are type A. Type A flue antigens have a very remarkable ability to change from year to year so it is not possible to be vaccinated permanently.
The World Health Organization, WHO, collects information from all over the world about ongoing epidemics and the types of vira involved in order to be able to produce vaccines against new subgroups in time.
Vitamin D against the flu
Cases of the flu almost only occur in winter. One theory says that flu arises not as a result of infection, but rather as a result of dormant viruses in the body, which are activated by a deficiency in Vitamin D during the winter half-year when there is less sunlight.
Flu epidemics often begin quite suddenly and the number of sick people increases the following weeks. After 2 - 3 months, the epidemic is usually over. During an epidemic many people will be infected with the flu virus without getting ill. However, children, elderly people, and people with weak immune systems, will develop symptomatic flu.
Infection with the flu virus most often happens from coughing and sneezing people who are already infected. Hand-to-hand and other personal contact also can transmit the disease, especially under unhygienic conditions. The incubation period , the time from being infected until the first symptoms appear, is 18 - 72 hours.
When the virus enters the airways, it invades the body cells and forces them to produce new vira. When the cell is filled with vira, in a matter of 4 - 6 hours, it bursts and sends the new vira into the blood from where they invade new cells. Every time a new generation of vira enters the blood, the temperature rises, because fever is the body's way of fighting off vira. The other symptoms, such as sneezing, coughing, headache, and muscle pain are also worsened. Gradually, the body's immune system fights off the new vira, partly by producing antibodies against the attacking flu virus. The fever abates and the symptoms disappear.
A non-complicated flu generally lasts between 3 and 5 days and most people recover after one week. Some people, however, especially the elderly, are tired and weak for several weeks, partly because the body strains depots of vitamins and antioxidants during illness.
A common complication of relation the flu is pneumonia, which can be caused by the virus itself or by bacteria attacking the already weakened person. The risk is higher if the person affected with a case of the flu has previously suffered from lung disease.
It can be difficult to distinguish the flu from another kind of microorganism, Mycoplasma pneumoniae, which also has a tendency of causing pneumonia. In contrast to the flu, the treatment for this microorganims is antibiotics.