10 Flu Symptoms

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: 1 Cough. 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. 2 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... 3 Headache. As the body fights against the virus, the temperature increases. This results in a vasodilatation of blood vessels throughout the body, including the brain, which results in a headache. Another reason may be sinusitis that often develops during the influenza infection (particularly in people who already suffer occasional episodes of sinusitis). In the absence of sinusitis, as the body temperature drops, the headache decreases. A persistent headache that intensifies when coughing is a characteristic of sinusitis. Rarely, some patients report a severe headache accompanied by a stiff and painful neck. This symptom requires immediate medical attention. 4 Runny or stuffed nose/ sneezing. In the first days of infection, the nose is often runny. One of the defense mechanisms of the upper respiratory tract is excessive mucus production accompanied by sneezing. This is the body attempting to get rid of the virus from the surface of the epithelium. As the inflammatory response and virus-induced damage intensify, mucous membranes swell, causing a stuffy nose and breathing difficulties. This symptom is not only unpleasant, but it can cause complications such as sinusitis or middle ear inflammation (due to compromised drainage of the middle ear and sinuses, mucus piles up providing perfect conditions for bacterial infection). 5 Swollen and painful lymph nodes. This symptom may be particularly prominent in children. The affected lymph nodes (typically those under the chin) are swollen and sore. The severity of this symptom differs among patients. Typically, in viral infections, only nodes on both sides of the jaws are affected. On the contrary, in bacterial infections, nodes on one side are more prominent than on the other. How do you tell if the nodes swollen? Gently touch the area under the chin and jaw with the fingertips. If swollen, it should feel like touching a small marble of rubbery consistency. 6 Gastrointestinal symptoms. Some people experience gastrointestinal symptoms such as nausea, vomiting, stomach cramps and diarrhea. These symptoms occur because of increased body temperature and the viral damage done to the epithelium of the intestines. Although quite unpleasant, these symptoms are rarely severe. Keep in mind that children are particularly sensitive to body fluid changes due to diarrhea and vomiting. Oral rehydration therapy or even in-hospital dehydration treatment may be needed. Typically, gastrointestinal symptoms develop quickly (sudden diarrhea, for example) and subside after 1 or 2 days. 7 Muscle aches. The immune response is a potent protection system against infective agents (such as the flu). The thing is, as it fights against the flu, it affects the body cells as well. By “affects” I mean damages and kills them. As a result, the pain in the muscles and joints kick in (within the first 2 or 3 days of a disease and is present for 4 to 5 days). 8 Fatigue. Fatigue is an unspecific symptom, but is the first sign of flu. Some people find it is so severe they can not get out of the bed for days. Because of different hormonal settings, women tend to handle flu symptoms better. This is possibly the reason for the popular term 'man flu'. 9 Breathing problems. Breathing difficulties is not a typical symptom of flu, but a characteristic for some of its complications. It may be present as a mild discomfort, but heavy breathing, chest tension, and wheezing are never signs of flu! If you are experiencing these symptoms, a medical examination is needed. Patients with chronic bronchitis or smokers will experience an episode of bronchitis during influenza infection. The flu can trigger asthma attacks and worsen the symptoms of it (only in patients who already suffer asthma). In general, patients with chronic pulmonary diseases are prone to developing flu complications, and they should be particularly cautious about breathing difficulties during influenza infection. 10 Worsening of long-term medical conditions. Although not relevant for people with good overall health, those with chronic diseases should be aware of this. For example, diabetic patients may notice that their blood sugar regulation is worsening (quite often, readjustment of insulin dose is necessary). Patients with kidney function impairment or chronic liver disease also might experience worsening of their chronic condition.

6 Gastrointestinal symptoms

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