Why is flu dangerous

Winter is coming, bringing more cases of flu. What are its symptoms?

Winter is coming, bringing more cases of flu. What are its symptoms?
O. Belousov, Grodno

We all need to beware of fluPeople of any age are susceptible to flu, with the symptoms usually including coughing and sneezing. A patient is infectious from the first hours and for up to 3-5 days thereafter (but usually for at least 1-2 days). The virus transmits through the air, via the smallest drops of saliva or mucus which contain the flu virus, at a rate fast enough to form an epidemic or pandemic. Transfer happens not only by air — through cough, sneezing and conversation — but may occur by touching everyday objects — such as door handles, towels or toys — upon which droplets have settled.

Flu epidemics caused by serotype A arise every 2-3 years, while those caused by serotype B every 4-6 years. Serotype C does not cause an epidemic, affecting only individual children and those who are debilitated. The autumn-winter period is the most common time for the flu to spread, although the virus is present all year.

Flu viruses are passed so easily that 50-70 percent of the population fall ill, quickly bringing an epidemic. Periodicity of epidemics is connected with frequent change of the virus’ antigenic structure. While people of all ages may succumb, more than 60 percent of those affected are children. The elderly, pregnant women, people with heart or lung disease and those with compromised renal function are also at most risk. Patients may experience the same flu virus with varying intensity.

The virus affects the mucous membranes of respiratory passages, as well as the nervous and cardiovascular systems, and is especially dangerous for children under the age of 1 year, the elderly and those suffering from chronic illness. The flu virus enters via the nose, throat or bronchial tubes, via the ciliated epithelium cells of upper airways, and multiplies until it destroys the cells, causing irritation of the upper airways: cough, sneezing and congestion. The virus has a toxic effect on the blood, bringing a rise in temperature, fever, muscle pain and headache. It also makes the patient susceptible to secondary infection and complications, since it lowers the body’s capacity to fight off other illness.

Clinical presentation. Flu symptoms are not specific, and cannot be distinguished from other ARVI without laboratory testing; ‘flu’ is diagnosed when an epidemic is observed in a particular area. In fact, the treatment for ‘flu’ and ‘ARVI’ are identical. The incubation period can last from several hours to 3 days, usually 1-2 days.

The illness has a fast onset, arriving with a bad headache, focused on the forehead, temples and superciliary arches. The patient will feel an ache through their body, as well as experiencing fever and general weakness. Their temperature may rise to 39-40°С (remaining high for 1-2 days) and they will feel pain on moving their eyes, as well as dizziness — sometimes by sensitive to the light. After a few hours, the throat becomes dry, causing tickling and a dry cough, accompanied by chest pain, and a blocked nose. The face and eyes redden and the lips and nose may develop sores. Nosebleeds sometimes occur. From the second day, there appears a moderate discharge from the nose, and the cough becomes productive on the third or fourth day. Those suffering from flu may find it hard to sleep and their appetite disappears.

Most people recover within 3-6 days (even 5 days) although the patient may continue to feel weary, especially those who are elderly.

In severe cases, vision may be clouded, and there may be delirium, with meningeal symptoms, vomiting and/or spasms (more often in children). Secondary bacterial complications may become evident.

The danger of flu lies in the risk of serious complications — especially among children, the elderly and weakened patients. Chronic diseases can be aggravated by contracting flu, and can result in fatality: most at risk are children under the age of 2 years and those aged over 65 years.

Immunity can be developed, but only against the strain previously contracted, and flu viruses are known for regularly changing their structure.

Next time, we will talk about how best to prevent the flu.

By Tatiana Zhukova, doctor of higher category, D.M. Ph.D.
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