| What is Influenza? | | | | vaccines may not help against a new form of virus. |
| Influenza is an infection caused by a virus of the | | | | Influenza viruses spread from one person to another |
| respiratory tract. Influenza is a very contagious | | | | through coughing or sneezing. Influenza can also be |
| infection and can easily break into a pandemic. You | | | | transmitted by indirect contact with a contaminated |
| may catch this infection from an infected person | | | | object or surface and then with your own mouth, |
| who is travelling with you or is working with you or | | | | eyes, or nose before washing your hands. |
| from an infected family member. Influenza virus may | | | | Treatment Available for Influenza |
| infect others around even if the infected person has | | | | Current influenza vaccines contain either inactivated |
| no illness symptoms. Influenza viruses can enter the | | | | virus, treated so that it cannot cause infection, or |
| body through the mucous membranes in the mouth, | | | | virus components. Recent vaccines contain a mixture |
| eyes, or nose. | | | | of two influenza A subtypes and one influenza B |
| Influenza is also known as ‘flu’ and crops up | | | | virus. The vaccines are very effective and have been |
| mostly in winter between October and March. The | | | | shown to reduce hospital admissions for pneumonia. |
| symptoms of influenza are as follows: | | | | All viruses used in vaccine production are currently |
| - Fever – usually continuous and may be lower in | | | | grown in chicken eggs, and experimental vaccines |
| older adults than in children and young people | | | | made in mammalian cells are likely to be the next |
| - Muscle pain and body aches – often severe, | | | | development in vaccine production. |
| usually in the arms, back and legs | | | | Changes in the virus due to antigenic drift or antigenic |
| - Headache – severe pain | | | | shift mean that the vaccine must also change to |
| - Loss of appetite – mainly due to a feeling of | | | | cover the prevailing strains of the virus; last |
| illness or fatigue | | | | year’s vaccine may not protect against this |
| - Dry cough, sore throat or runny nose – more | | | | year’s virus. |
| visible when the fever goes away | | | | The composition of the influenza vaccine for the |
| Other symptoms are usually more severe, when | | | | next season is coordinated by the WHO. The ability |
| fever is high. Symptoms such as vomiting or | | | | of influenza to continually undergo antigenic change |
| diarrhoea are not related to influenza as opposed to | | | | ensures that there is always a possibility that new |
| what most people believe. | | | | variants not covered by the vaccine will appear which |
| Causes for Influenza | | | | may give rise to serious epidemics. This means that |
| Influenza is caused by flu viruses. There are mainly | | | | making a completely accurate prediction of likely |
| three types of flu viruses – type A, B and C. | | | | influenza activity for the oncoming season is very |
| Influenza A viruses are found in humans and animals, | | | | difficult. It should also be remembered that during the |
| whereas B and C are found only in humans. Influenza | | | | annual winter influenza season, other 'flu-like' viruses |
| A virus possesses two surface proteins, | | | | also circulate, against which influenza vaccine offers |
| haemagglutinin (H) and neuraminidase (N), which are | | | | no protection. The vaccine should not be given to |
| used to classify the virus into subtypes. The natural | | | | people who are allergic to egg products. |
| reservoir for influenza A is considered to be aquatic | | | | Influenza A infections can be prevented to a certain |
| birds, as all influenza A subtypes are found in these | | | | extent with drugs which effectively prevent illness. |
| birds, whereas only certain subtypes are found in | | | | The combination of vaccination with prophylaxis |
| mammals. These two surface proteins may undergo | | | | offers the highest level of protection for high-risk |
| change over time. | | | | patients. |
| Minor changes are termed antigenic drift, while major | | | | Tamiflu (Oseltamivir) as Best Influenza Treatment |
| changes in one or both of the surface proteins, is | | | | Tamiflu is a unique medication and helps in treatment |
| called antigenic shift. The importance of these | | | | as well as prevention of influenza. It is also |
| changes is that antibodies in the blood, which are | | | | recommended by World Health Organization in case |
| responsible for protection against repeated infection | | | | of influenza pandemic and bird flu outbreak. Tamiflu is |
| with the virus, are less effective if the virus surface | | | | a safe and effective drug; however, it would be |
| protein changes; the greater the change, the less | | | | misleading to say that it is the best influenza |
| effective is the antibody. Only influenza A can | | | | treatment. Different people react differently to |
| undergo this dramatic variation in which a virus of a | | | | medications and hence you might find Tamiflu to |
| new subtype can suddenly appear in the human | | | | work well for you but might not work the same way |
| population; influenza B and C viruses appear to be | | | | in another individual. It is best to follow the |
| more stable than influenza A. | | | | doctor’s instructions in these cases. |
| It is this antigenic shift that can be the catalyst for a | | | | Tamiflu is of proven effectiveness in the treatment |
| nation-wide epidemic, or more seriously a world-wide | | | | of influenza. New types of anti-influenza drugs are |
| pandemic. The latest example of an emerging new | | | | currently under development. Patients should rest, |
| subtype is the ‘bird flu’, first isolated in Hong | | | | keep warm and take plenty of non-alcoholic fluids |
| Kong in May 1997, which previously had only been | | | | plus any medication recommended by their doctor to |
| found in birds and was not associated with disease in | | | | relieve symptoms. Antibiotics are of little value |
| humans. | | | | except in patients in whom bacterial pneumonia |
| As Influenza viruses are known to mutate over time, | | | | occurs. |
| new vaccines have to be developed constantly. Old | | | | |