It's impossible to provide an exact number for "unknown" diseases, as by definition, they are not yet identified or characterized. However, we can infer based on the number of known rare diseases and the ongoing discovery of new conditions that a significant number remain to be discovered.
Here's why it's difficult to quantify:
- Definition of "Unknown": A disease is considered "unknown" until its cause, symptoms, and progression are understood well enough to differentiate it from existing diseases. This process can be lengthy and complex.
- Ongoing Discovery: Medical research is constantly uncovering new diseases or identifying previously unrecognized variations of known diseases.
- Diagnostic Challenges: Some diseases may exist but are misdiagnosed or remain undiagnosed due to limited access to healthcare, lack of specialized testing, or overlapping symptoms with other conditions.
Considering that the National Institutes of Health (NIH) recognizes more than 7,000 rare diseases, and given the limitations of medical knowledge and diagnostic capabilities worldwide, the number of currently "unknown" diseases could potentially be substantial. It is highly likely that many more diseases remain to be discovered and characterized. This field is an active area of medical research.
Therefore, while a definitive number cannot be given, it's reasonable to assume that a significant number of unknown diseases exist.