Pneumonia is an infection of the lungs that can be caused
by many different microorganisms. These include viruses, bacteria,
parasites, and fungi.
What is going on in the body?
Pneumonia occurs when an infectious organism causes
inflammation in the lungs. The air sacs fill with liquid and mucus. This
means they can't deliver oxygen as well to the blood vessels.
What are the causes and risks of the infection?
Pneumonia is a fairly common infection that affects people of
all ages. Some of its more common causes are as follows:
bacteria, such as Streptococcus pneumoniae,
Staphylococcus aureus, and Haemophilus
fungi, such as the organism that causes
organisms similar to bacteria, such as the ones that cause
parasites, such as Pneumocystis carinii, which is
often seen in people with AIDS
viruses, such as the ones that cause
The following factors can increase a person's risk of
developing severe pneumonia:
chronic disease, such as diabetes
or heart disease
chronic obstructive pulmonary disease,
such as emphysema
a weakened immune system