Don't forget that there is a difference between the diagnosis of a particular disease (with all the symptoms and dysfunctional metabolic processes that the disease entails), and the original causes (microbial, toxic or genetic) of that disease. For example: type 1 diabetes is an illness in which the pancreas does not produce enough insulin, due to damage or death of the insulin-producing beta cells in the pancreas. If you get diagnosed with type 1 diabetes, this diagnosis is given on the basis of your symptoms and blood tests that show low insulin. However, what causes type 1 diabetes in the first place is a different question. In fact, oddly enough, enteroviruses are also strongly suspected, as it is thought enteroviruses may infect and destroy the insulin producing beta-cells in the pancreas, and also enteroviruses may damage or destroy these cells via the indirect autoimmune mechanisms they precipitate (refs: 1, 2, 3, 4, 5). So similarly, ME/CFS is a disease that has certain symptoms and certain dysfunctional metabolic processes, and diagnosis should ideally be on the basis of those symptoms and dysfunctional metabolic processes. But what causes ME/CFS in the first place (in terms of microbes, toxins genetics, and other factors) is another question, which is a different question to the diagnosis of the condition.