The flu is a respiratory viral infection caused by the Influenza virus. It has a seasonal character. Every year the influenza virus starts its world tour, mutating as it goes which is the reason we can’t build permanent immunity against it.
The flu virus is passed from person to person. As it touches the epithelium of the upper respiratory tract, infection begins. The virus attaches, invades the cells, multiplies, kills the host cell and spreads further. The incubation period (the time between the infection and onset of the symptoms) lasts 1-3 days. During this period, some people experience fatigue, light-headedness, and other unspecific symptoms.
The best way to prevent flu is by vaccination. The Centers for the Disease Control and Prevention recommend that all people older than six months of age should get vaccinated.
Although flu is not considered dangerous, chronic pulmonary patients and immunocompromised patients (HIV, Hepatitis B or C, chemotherapy, people with congenital immunodeficiencies, etc.) should be extra cautious if they get infected.
Common symptoms of flu include:
A cough is rarely the first, but certainly the most characteristic symptom of respiratory infections. At first, the cough is not productive, which means that no sputum is produced. The coughing reflex, at this stage of disease, is triggered by damage to the lining of the respiratory tract (epithelium). As the infection slowly heals, cilia in the lungs recover and start to work hard trying to drain piled up mucus, which causes a productive cough.
Fever/ Chills/ Shivering
Fever and chills go hand in hand. Fever can sometimes raise the body temperature above 39.5°C. Although common with flu it’s not always present. It is possible to have all flu symptoms (even chills) except fever. Shivering accompanied with chills is often present as the temperature increases.
Fever can be easily reduced with over the counter anti-inflammatory drugs. Although safe, people with certain health conditions, such as stomach ulcer, should avoid using them. Always consult your doctor if you are unsure.
More symptoms on next page…