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INFLUENZA (FLU)

What is Influenza ?

The disease known as flu is caused principally by influenza viruses types A or B. Influenza has affected millions of people throughout history. It causes illness worldwide, and sometimes with devastating effect when it occurs as an epidemic. One to two days after being infected the patient becomes suddenly ill. Many patients can tell exactly when they first felt ill. This starts usually with chills, muscle ache, headache, cough and fever. The temperature rises rapidly to 38 to 40 C. This lasts for a couple of days and the patient recovers completely within a week. Occasionally, complications may occur due to added bacterial infection of the lungs. This is particularly likely in the elderly and those with longstanding lung or heart conditions.

How does Influenza occur ?

An infected person spreads the virus by mucus from the nose and throat during sneezing, coughing or talking. A single infected person is able to transmit the virus to a large number of people. The virus attacks the lining of the air passages (the nose, throat, windpipe and lungs) causing inflammation.

Why does Influenza occur ?

The viruses are present in the general population all the time in small numbers. The influenza season is usually winter. The cases may occur here and there, or may affect a large number of people. This is called an epidemic. When a person is infected by an influenza virus, his body responds by forming antibodies against that particular type of the virus. If that same type of virus then infects the person again, he will not be affected as he is now protected by the antibodies from the previous infection. The problem with the influenza virus is that it keeps on changing its type. This allows the virus to cause another flu infection in that same patient.

Treatment Involved for Influenza

Bed rest, plenty of fluids and paracetamol or ibuprofen are needed to relieve the headache and reduce the fever. Aspirin should not be given to children. Like most other viruses, the influenza virus itself cannot be treated with antibiotics: it will always be dealt with by the body's own defences. You will only need antibiotics if you develop any complications such as bacterial infection of the lungs. Two drugs, amantadine and rimantadine have been used to have a limited effect on influenza A only. They are not widely used as it is not possible to tell, without tests, who has influenza A or influenza B. Another reason they are not prescribed is that they do have side effects. Two new antiviral drugs (zanamivir and oseltamivir) have been shown to reduce the duration of ‘flu’ by one day. To be effective, they need to be taken within 36 hours of the onset of ‘flu’. They are not widely used as their benefit is slight.

During Treatment for Influenza

The symptoms usually get better after one week. As mentioned above, some people develop bacterial lung infection. This complication, which is a type of pneumonia, causes the phlegm to become yellow. Fever may get worse again. The doctor may prescribe antibiotics to treat this.

After Treatment for Influenza

You may need more than one week to recover, and may be left feeling rather tired. You should resume normal activities gradually. Vaccination is available in the form of an injection consisting of the most recent types of the flu viruses causing illness in the community. It should be given before the start of the influenza season, in the autumn (October and November). It is mainly given to protect people who might be seriously ill if they get influenza. These include those over 65, or people with heart, kidney and lung disease, as well as diabetics.

If Influenza is Left Untreated

In most patients the flu would get better provided there are no complications. In some people weakened by age or other disorders influenza has been known to be fatal. There are no permanent after-effects.

Effects on Family of Influenza

Personal hygiene is important to avoid the rest of the family becoming infected. The wearing of surgical masks (available from pharmacies) may be worthwhile for any contacts who might be at particular risk.