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October to March is flu season, the time when many fall victim to the sniffles. Flu is actually an infection that affects the nose, throat and lungs. It is usually due to a locally active virus that belongs to Influenza group A or B. Since the groups contain a large number of viruses, different strains cause infections every year. Rarely, the flu is due to an internationally virulent strain that rapidly spreads across the globe, such as swine flu or avian flu.
Young children, the elderly, pregnant women and those who are suffering from chronic illnesses that have compromised their immune system are particularly vulnerable. This leaves out only teenagers and young adults who are in robust health!
The infection follows anywhere between two and 10 days after exposure to the virus. Initially, it may be confused with a common cold. Colds affect people several times a year whereas flu occurs once in several years. Also with flu, several people are affected within a short space of time, either in school, college or the workplace.
Flu usually starts abruptly, with a runny nose, cough, fever (over 100°F), chills, dizziness, flushed face, headache, backache, leg and muscle pains. There may be nausea, vomiting and lack of energy. The symptoms are similar to that of a common cold and it may be difficult to distinguish between the two. In the case of flu the symptoms appear with no warning and are severe from the beginning. The first symptom is often fever. In adults the temperature is usually lower than in a child. Colds start slowly and gradually.
The fever as well as aches and pains begin to fade on days 2-4, but this is followed by the appearance of new symptoms such as a dry cough, rapid breathing, sneezing and sore throat. These symptoms also usually last 4-7 days. The flu can make asthma, breathing problems, and other long-term illnesses worse.
Recovery from the flu may not be complete for weeks. The fever and other symptoms may disappear only to be followed by tiredness, depression, inability to cope with work and lethargy. Secondary lung infection can cause the fever to return. The appetite may remain poor.
The flu virus lives in the respiratory tract. Coughing, sneezing or even talking expels the viral particles in the air. They remain suspended as they are very light and can be breathed in by others. They also tend to settle on surfaces such as tables, walls, telephones and computer keyboards. Others touching the surfaces transfer the particles to their respiratory system and acquire the infection.
In closed spaces such as metros, aircraft, shopping malls and classrooms, the infection spreads like wild fire. A large number of people are affected in a very short space of time. The flu becomes an epidemic.
The virus that causes flu mutates rapidly, changing all the time. Recovery from one episode does not provide protection against a second attack from a different strain. The second attack may be milder if there is some genetic material that is common between the strains.
Young healthy adults recover from flu with no long-term after effects. Children and the elderly can develop complications such as pneumonia, bronchitis, sinusitis or ear infections. These are virulent bacterial infections that gain a foothold because the respiratory system is weakened by the viral attack.
Recovery from the flu takes time. Bed rest, plenty of fluids and paracetemol for the pain is usually all that is required. Aspirin should not be used in flu. In children and teenagers it can cause a rare fatal reaction known as Reye’s syndrome. Some anti viral medications such as oseltamivir (Tamiflu) or zanamivir (Relenza) can be taken. They have to be started early on in the illness in adequate dosages. They can shorten the duration of illness and reduce the complications. Tamiflu is taken orally and Relenza is inhaled. These medications have side effects. They can induce nausea and vomiting. They are contraindicated in asthmatics. Rarely, they can cause delirium. Inadequate dosing can do more harm than good. The virus can become resistant to the medication.
Every year the pharmaceutical companies release “flu vaccine.” A new vaccine is released every year with the three most common strains likely to cause an epidemic that year. It can be an injectable vaccine or a nasal spray. Protection is more than 90 per cent.
Washing hands frequently with soap or an alcohol-based hand sanitiser prevents the virus from being carried on the hands. The nose and mouth should be covered while coughing or sneezing. A tissue, which can be discarded, is more hygienic than a cloth handkerchief. If neither is available then sneeze into the crook of the elbow. Crowded places increase the risk of transmission, so it is best to avoid them if possible during the flu season.
Dr Gita Mathai is a paediatrician with a family practice at Vellore. Questions on health issues may be emailed to her at yourhealthgm@yahoo.co.in
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