WHO IS AT RISK?
INFLUENZA also commonly known as the flu, is an upper respiratory tract infection caused by a virus which belongs to a group of viruses called orthomyxovirus. They exist in 2 main forms, A and B. Influenza B is associated with localised outbreaks of mild nature whilst influenza A is more serious and can cause world wide pandemics. Epidemics of influenza come mainly in the winter months.
Influenza is usually a self-limiting illness but can lead to significant morbidity and mortality particularly in those with chronic chest or heart problems.
The most serious pandemic of influenza occurred in 1918 and is reckoned to have caused more than 20 million deaths worldwide. Because the virus mutates quite regularly it results in different strains and therefore difficulty in producing a long lasting vaccine.
The clinical features of influenza varies but usually after 1 - 4 days of incubation the infected person typically presents with generalised aching, fever, shivering and headache. There may be a sore throat and a persistent dry cough which can sometimes last for many weeks. The patient usually complains of sweats and dizziness. After 2 -3 days the fever settles and there is a slow recovery but in a few people the period of recovery can be particularly long and associated with depression which may take months to clear and this is known as the post viral syndrome.
Sometimes complications can occur in the elderly and those with pre-existing medical problems such as heart and lung problems. Complications can include severe chest infections such as pneumonia and bronchitis, heart failure and even, although in very rare circumstances, swelling of the brain and meningitis.
There is no cure for influenza and it is usually regarded as a self-limiting illness. Patients who have been infected should be treated symptomatically using regular Paracetamol, drinking lots of fluid and bed rest. In people who have developed complications, such as bronchitis, an antibiotic may be indicated.
During an epidemic where many people are infected and the virus is circulating in large amounts, certain people who are regarded as being
"at risk" i.e. those with heart and lungs problems as well as other serious medical problems, may be offered
a specific anti-flu medication such as Zanamivir. This drug stops the virus from multiplying and has been shown to reduce the duration of symptoms in some people, by up to one and a half days. It is only of benefit in people who present within 48 hours of developing flu like symptoms.
The only truly effective treatment for influenza is prevention. This is in the form of vaccination. The vaccine is an inactivated form of the virus that is predicted to cause an epidemic in a particular year. As it is inactivated it is impossible for it to cause the actual disease in the person vaccinated. Influenza vaccines should not be given to individuals who are allergic to egg protein as some are manufactured in chick embryos. New vaccines have to be prepared to cover each new mutated virus and are therefore in limited supply at the start of an epidemic.
Routine vaccines are therefore reserved for susceptible people who have the following problems:-
Chronic Respiratory Diseases including asthma, chronic heart disease, chronic renal failure, diabetes, immunosuppressant due to disease or treatment. People who have had their spleens removed. All those aged 65 years and over. Residents in nursing homes and residential homes and long stay facilities. Certain health service staff during epidemics.
Most GP surgeries hold clinics during October and November to provide these to their 'at risk' patients. It can take between 10 and 14 days following immunisation before protection is acquired. The immunity expected can be up to a year from the time of vaccination.
The vaccines are usually very safe however, some people may complain of fever or aching which can start 6 hours or so after vaccination and can last up to 48 hours. Very rarely an allergic reaction can occur in people who have an egg protein hyper-senstivity.
Remember that influenza can kill up to 4000 people a year in this country, so if you are at risk make sure you go and have your jab straight away.
This article was written for us by Dr Hilal Mulla,
a practicing GP in Churchtown Southport.
He is a member of the Royal College of General Practitioners.