Is it necessary for a condition to be caused by micro-organisms for it to be called a disease?
Here’s how Encyclopædia Britannica defines disease:
disease, any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and differing in nature from physical injury. A diseased organism commonly exhibits signs or symptoms indicative of its abnormal state. Thus, the normal condition of an organism must be understood in order to recognize the hallmarks of disease. Nevertheless, a sharp demarcation between disease and health is not always apparent.
(source)
Note how it does not mention infections or communicability.
Besides, cardiovascular conditions like heart attack and stroke, chronic respiratory conditions like asthma, and inherited conditions like Down syndrome, cystic fibrosis, and Huntingtons, are all classified as diseases by the WHO (source). In other words, conditions caused by genetics or other non-microorganism factors are also diseases.
In any case, in the end it boils down to semantics. Which is quite unhelpful. As a layman, I go for the more pragmatic approach and use the terms like the experts use them.