What is the differences between an illnesses, syndromes and diseases?

Answer 1

The state of "illness" is subjective. It pertains to the person's interpretation of their symptoms (for example, a person can say "I'm feeling ill"). A person can feel ill because of a disease or syndrome, but illness is a general term that describes a condition that is happening to the person and how they're experiencing it. Most people, but not all, feel "ill" when they have a cold, whereas some other person with the same cold may say "despite having a cough and runny nose, I feel pretty well".

A disease is a a well-defined condition that can be objectively diagnosed (most of the time). Diabetes is a disease because it has specific criteria that are met to give the diagnosis. Diseases can be acute or chronic (short-term or long-term), and can be curable or incurable, or terminal (inevitably causing death).

A syndrome refers to a group of symptoms that may or may not point to a definable condition. An example of a syndrome is "chronic fatigue syndrome" which is a group of symptoms that may include the person feeling excessively tired despite getting rest, sleeping too much, having vague aches and pains that can't be attributed to another disease process or injury. Many syndromes are diagnoses of exclusion, meaning the symptoms fit the description of a condition (syndrome) after other causes can be ruled out. Another syndrome that is well-known is "Down Syndrome". While there is one very concrete definable characteristic (an extra chromosome), there is a broad spectrum of other things that a person with Down Syndrome may or may not have. Some people with DS have obvious physical disabilities or cognitive disabilities, while others are not limited in this way. Heart and kidney conditions are not uncommon for DS persons, but you can still have DS and never have any of those commonly co-occurring issues. I hope this is helpful information!

References

Calvo, F., Karras, B. T., Phillips, R., Kimball, A. M., & Wolf, F. (2003). Diagnoses, syndromes, and diseases: a knowledge representation problem. AMIA ... Annual Symposium proceedings. AMIA Symposium, 2003, 802.

Genetic, Metabolic & chromosomal disorders. Kennedy Krieger Institute. (n.d.). https://www.kennedykrieger.org/patient-care/conditions/genetic-metabolic-chromosomal-disorders