Pneumonia is caused by an infection in the lungs. The infection affects the air sacs in the lungs rather than the tubes that carry air to and from the lungs. Infected parts of the lung fill up with fluid, which contains white blood cells that fight the infection.
What causes pneumonia? Where does it come from?
Pneumonia is caused by germs (tiny organisms that can cause disease). Viruses, bacteria and fungi are types of germ that can cause pneumonia. Healthy people don’t usually have these germs in their lung tissue.
Germs sometimes get to the lung through our bloodstream, but most often they reach the lung tissue inside tiny droplets of water in the air that we breathe in. Usually, these germs come from other people, who spread them by coughing and sneezing out the droplets of water containing the germs.
Sometimes, the germs come from more unusual places. Legionnaires’ disease is a type of pneumonia caused by germs that thrive in very warm water. The germs that cause psittacosis are usually caught from birds, especially parrots. MRSA is often found in hospitals and can cause pneumonia in people who are admitted to hospital for other reasons.
Who gets pneumonia?
Anyone can get pneumonia, even people who are fit and healthy. However, germs are more likely to Infect a person whose immunity is low and their natural defences are weakened. Very young and very old people have weaker lung defences, so pneumonia is more common early and late in life.
Some other things that can weaken these defences are tobacco smoke, viral infections that attack the breathing tubes (such as the common cold) and other viral infections (such as HIV). Some medicines, like those given for cancer therapy, also weaken the immune system, and a serious illness or an operation can make people more vulnerable. This is why patients sometimes develop pneumonia when they are already in hospital for another reason.
Would I know if I had pneumonia?
If you had pneumonia you would certainly know you were ill, but you might not know you had pneumonia, as the symptoms can be confused with other illnesses. Common symptoms include:
- cough, sometimes with yellow, green or blood-flecked phlegm
- chest pain, which may get worse when you breathe in
- a high temperature
- shivery episodes
- loss of appetite
How would a doctor know if I had pneumonia?
As well as asking about your symptoms, the doctor may be able to hear noises when he or she listens to the affected part of the lung with a stethoscope. The diagnosis is not easy to make, however, and often it is only confirmed when a chest X-ray shows that there is fluid in part of the lungs.
How is pneumonia treated?
Antibiotics are the main treatment for pneumonia. Most people will get better at home, but more severely ill people will have to go to hospital so that oxygen can be administered and fluids given in a drip. Although most people get better, if the pneumonia is very severe, people can die, even with the best treatment.
What should I do if I, or someone I care for, gets pneumonia?
If the doctor has prescribed medicine, be sure to take it at the right times and to finish courses of antibiotics. If you are not getting better with treatment, and especially if your temperature is not getting back to normal or breathing is becoming difficult, contact the doctor again. You may feel better in a room with a humidifier, which increases the moisture in the air and soothes irritated lungs. Make sure you drink plenty of fluids, especially if you have a fever. Finally, be sure to rest.
How quickly should I get better?
Most symptoms, such as chest pain and fever, get better in a few days. The cough usually takes 2 or 3 weeks to go, but tiredness and weakness can take as long as 6 months to clear completely. If your symptoms do not get better as expected, or if the illness seems to come back, your doctor will want to look for any underlying reasons you may be particularly at risk of pneumonia.
Can I do anything to prevent pneumonia?
The germs that usually cause pneumonia are very common and are hard to avoid. However, avoiding actions that harm the lung’s defences (such as smoking) can help. Vaccines can prevent some types of pneumonia and most countries recommend that they are used in those people who are most at risk (the elderly). Influenza and pneumococcal vaccines are the types most commonly recommended.