Pneumonia: The disease that kills 80 every day

There are more than 30 different causes of the illness.

Tragically, around 80 people die in Britain every day from flu and pneumonia – a figure higher than anywhere else in Europe.

Elderly people, children and people with chronic disease, including Chronic obstructive pulmonary disease and asthma, are most at risk.

It is an illness that can quickly see a deterioration in the health of those unfortunate enough to contract it.

This was sadly apparent in the case of 15-year-old Callan Fendall-Betts from Dudley, who died on New Year's Eve having become ill just a few days earlier.

The youngster's condition deteriorated rapidly from the moment he entered hospital – a sadly all too common occurrence in pneumonia sufferers.

Under normal circumstances the human body is able to filter out most germs in the air and stop infections from reaching the lungs.

But even if germs do make it through to the lungs, or an infection spreads from another part of the body, a healthy person's body will be able to deal with the problem.

As pneumonia spreads through the lungs, the body fights back and white blood cells attack the germs. The infected area becomes inflamed. This is part of the body's normal response to infection.

In a healthy person, these natural defences will overcome the pneumonia. But in someone with a weak immune system, the infection cannot be contained.

At the ends of the breathing tubes in the lungs are the tiny air sacs where oxygen passes into your blood – the alveoli. As these become infected, they start to fill up with fluid and pus.

This disrupts the normal process of gas exchange in your lungs, and stops oxygen from reaching the blood stream as well as causing a rise in blood levels of the waste gas carbon dioxide, which cannot be so easily removed. As a result the person becomes short of breath.

If left untreated, oxygen levels can fall to dangerously low levels. If the body's tissues – especially in the heart and brain – do not get the oxygen they need, confusion, coma, heart failure and eventually death may result.

Bacterial pneumonia tends to be more serious as it causes more severe symptoms.

But viral pneumonia – caused by the flu virus – can also be life-threatening if it triggers a particularly severe inflammation of the lungs or is complicated by a secondary bacterial infection.

In the early stages of pneumonia the most common symptoms are a cough (with some pneumonias you may cough up greenish or yellow mucus, or even bloody mucus), fever, which may be mild or high, shaking chills and shortness of breath, which may only occur when you climb stairs.

Additional symptoms include sharp or stabbing chest pain that gets worse when you breathe deeply or cough, headache, excessive sweating and clammy skin, loss of appetite, low energy, and fatigue, and confusion, especially in older people.

Many different germs can cause pneumonia, but there are five main causes: bacteria, viruses, mycoplasma (a type of bacteria that is resistant to penicillin), other infectious agents, such as fungi, and various chemicals.

If you have viral pneumonia, you also are at risk of getting bacterial pneumonia.

The main cause of pneumonia is the bacteria streptococcus pneumoniae. Professor Brian Duerden CBE, the chief micro-biologist at the Department of Health, said the bacteria can also cause or lead to numerous other invasive infections.

"It can cause other chest infections in old people as well as pneumonia," he said.

"It can affect young children when it can get into their blood streams. It can cause septicemia. It is also the most important cause of meningitis in very young children.

"In some people it can get into the sinuses and into the middle ear and cause further infection."

Understanding the cause of pneumonia is important because pneumonia treatment depends on its cause.

Pneumonia is most likely to strike in winter, when its impact can be increased by the prevalence of viral infections such as flu.

For those who contract milder pneumonia, this will usually mean a few days or a week of being unwell, followed by a steady return to normal activity.

Severe pneumonia, which needs hospital admission, might mean it takes weeks or months to feel fully fit again.

If pneumonia is suspected, your GP will perform an examination of your chest, using a stethoscope to listen for signs of fluid on the lungs.

The patient will often then be admitted to hospital for X-rays to see how bad the infection is.

If the infection is mild, medication will be given and they will be sent home. If it is a severe infection, they may have to stay in hospital to be treated with intravenous antibiotics.

In the majority of cases, oral antibiotics successfully treat mild to moderate infections. In addition, a high fluid intake is recommended and sometimes painkillers may be needed.

Most people make a complete recovery but, although the fever may improve quickly, a feeling of tiredness and lethargy can persist for several weeks.

The vast majority of people will recover from pneumonia and return to good health. However, some people with severe pneumonia don't survive despite the best available care.

Figures from the British Lung Foundation show that up to 14 per cent of people who are admitted to hospital with pneumonia sadly die.