I mentioned in the first class that there were a number of different ways to classify diseases. We have generally been classifying and thinking about infectious diseases in terms of their causative agents.
However for many doctors, presented with a patient with an array of symptoms, it makes more sense to, at least initially, describe diseases according to their symptoms.
Pneumonia is an example of this someone raised in a question in the last class. Pneumonia is an inflammation of the lungs and can result from a wide variety of causes including bacteria, viruses, fungi, parasites and even non-biological sources such as dust.
Pneuomonia is actually an exception to the rule that the suffix -itis is used to indicate a disease marked by inflammation. You have probably heard of bronchitis, cystitis, laryngitis, meningitis, hepatitis etc - all of which name diseases that can be caused by a variety of organisms. In many cases knowing which organism is causing the disease is a vital next step.
Because of this association between the suffix -itis and disease people have sometimes coined words with it. The most common example being senioritis - taking it easy your senior year of high school. However, technically senioritis would refer to a swelling or inflammation of your seniors....