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What Is Flu?

What Is Flu?


This months feature focus from covers the difference between a common cold and flu, the various symptoms and recent preventions.
Last Updated: 27-Aug-2010

The common cold and flu are both contagious viral infections of the respiratory tract. Although the symptoms can be similar, flu is much worse. A cold may drag you down a bit, but the flu can make you shudder at the very thought of getting out of bed.
Congestion, sore throat, and sneezing are common with colds. Both cold and flu bring coughing, headache, and chest discomfort. With the flu, though, you are likely to run a high fever for several days and have headache, fatigue, and weakness. Usually, complications from colds are relatively minor, but a severe case of flu can lead to a life-threatening illness such as pneumonia. More than 100 types of cold viruses are known, and new strains of flu evolve every few years. Since both diseases are viral, antibiotics cannot conquer cold or flu. Remember: Antibiotics only treat bacterial infections.
A few antiviral medications are available to treat flu. But there are no medications that specifically defeat the common cold. Antibiotics may be helpful if there is a secondary bacterial infection.

"Stomach flu" is a popular term but not a true medical diagnosis. It's not uncommon to mistake gastroenteritis, which is what stomach flu is, for the viral infection we commonly call "flu." Gastroenteritis refers to irritation of the gastrointestinal tract (stomach and intestines). A virus, bacteria, parasites in spoiled food or in unclean water, or another agent can cause stomach flu. With gastroenteritis, you will have symptoms such as abdominal cramps, stomach pain, vomiting, nausea, and diarrhoea.
Symptoms of flu are similar to a cold except flu symptoms are much worse with fatigue, fever, headache, and respiratory congestion. Flu symptoms come on so abruptly that you may know the exact time you first came down with flu.

The flu virus is spread from person to person through respiratory secretions and typically sweeps through large groups of people who spend time in close contact, such as in daycare facilities, school classrooms, college dormitories, military barracks, offices, and nursing homes.
Flu is spread when you inhale droplets in the air that contain the flu virus, make direct contact with respiratory secretions through sharing drinks or utensils, or handle items contaminated by an infected person. In the latter case, the flu virus on your skin infects you when you touch or rub your eyes, nose, or mouth. That's why frequent and thorough hand washing is a key way to limit the spread of influenza. Flu symptoms start to develop from one to four days after infection with the virus.

Until recently there was no specific treatment for influenza, and for most people it is still best to treat the symptoms in the old fashioned way:
  • Stay at home.
  • Drink plenty of fluids.
Take symptom relief with:
  • paracetamol
  • aspirin (not in children under the age of 16)
  • ibuprofen or other anti-inflammatory drugs to help with fever and aches and pains.
  • decongestants
  • cough medicines
  • gargles, lozenges etc. to help with other symptoms.
  • If you are still hot, sponge down with tepid water.
  • Await natural recovery.

There are very few treatments that work on viruses. Those that do work on influenza need to be given within 48 hours of the onset of the attack, before it is possible to be absolutely sure of the diagnosis, and only shorten and reduce the severity of the condition. The other aspect of this is that they are only available on prescription, and if everybody with influenza were to see their doctor within two days of developing symptoms the healthcare systems in most countries, already stretched by an epidemic, would probably grind to a complete halt. Prevention, with influenza vaccine, is a far better option.
There are now three influenza treatments licensed for use in the UK:
  • amantidine (Synmetrel, Lysovir), which is taken by mouth
  • oseltamivir (Tamiflu), which is taken by mouth
  • zanamivir (Relenza), which is a powder that is inhaled.
Oseltamivir and zanamivir belong to a new class of drug (neuraminidase inhibitors) and are licensed for treatment of both the main types of influenza in humans (type A and type B). Amantidine has the benefit of being less expensive, but only works on type A.
The way in which these may be used within the National Health Service in England & Wales is set out by the National Institute for Clinical Excellence (NICE). Under the NICE guidelines:
None of these drugs (amantidine, oseltamivir, and zanamivir) is recommended for treatment or prevention of influenza in children or adults unless they are in the at risk groups.
Both oseltamivir and zanamivir are recommended for the treatment of at risk adults who can start treatment within 48 hours of the onset of symptoms.
Oseltamivir is also recommended for the treatment of at risk children who can start treatment within 48 hours of the onset of symptoms.
Amantidine is not recommended for the treatment or prevention of influenza.

You should consult your doctor if symptoms such as clouded/altered consciousness, breathlessness, or severe chest pain occur, and if you are concerned. Try not to call just because of the temperature, aches and pains, and cough, as there is nothing your doctor can do that you can not, and what is more, there are likely to be many other people with similar symptoms, stretching family doctor, nursing and hospital services to the limit.
If symptoms continue unabated for more than a week, or if you seem to be improving for a few days then get much worse again, it is worth asking your doctor's advice. Sometimes, during 'flu, a secondary infection gets in while the body's defences are down. This is most commonly a chest infection and can be a pneumonia. The secondary infection is often caused by bacteria, and as a result is likely to respond to an antibiotic.

There are many influenza viruses, often named after places where epidemics have occurred. There tend to be only one or two which reach epidemic proportions each year. By monitoring the progress of these worldwide, the World Health Organisation (WHO) each year decide on the best "cocktail" of influenza types to be included in that year's influenza vaccine.
A new vaccine is being developed that is said to be able to allow for different and new strains. This will have the benefit of lasting much longer when it is introduced. It may then become cost effective for the NHS and other healthcare systems to consider widespread immunisation. It is advised that people belonging to the following risk categories consider annual influenza vaccination. In the UK this is available from your doctor in October.

There are various groups who are more at risk during influenza epidemics. These include:
  • people aged 65 or older
  • people who have poor immunity
  • people with conditions such as diabetes, lung disease, kidney disease, heart disease, or liver disease.
Other people who are not at such risk from influenza might choose to have the vaccination, but in the UK this is not routinely covered the National Health Service.
The NICE guidelines recommend the use of oseltamivir to prevent influenza in the limited number of cases where:
someone (aged more than 13) from one of the at risk groups has been in close contact with someone with a flu-like illness and they have either not been protected by vaccination against influenza this season, or they live in a care home and influenza is circulating in the community. (Influenza: Information about the Infection and the Vaccine)