Shingles caused by varicella-zoster was regarded as rare disease, mostly related to childhood chickenpox. However, meningoencephalitis caused by varicella-zoster is increasingly recognized as a predominant cause of ME among immunocompetent adults in non-epidemic circumstances. Diagnosis of complications of varicella-zoster, particularly in cases where the disease reactivates after years or decades of latency, are difficult. A rash (shingles) can be present or absent. Symptoms vary, and there is significant overlap in symptoms with herpes-simplex symptoms. Although DNA analysis techniques such as polymerase chain reaction (PCR) can be used to look for DNA of herpesviruses in spinal fluid or blood, the results may
Psychogenic disease to be psychogenic include psychogenic seizures, psychogenic polydipsia, psychogenic tremor, and psychogenic pain. There are problems with the assumption that all medically unexplained illness must have a psychological cause. It always remains possible that genetic, biochemical, electrophysiological, or other abnormalities may be present which we do not have the technology or background to identify. The term "psychogenic disease" is often used in a similar way to "psychosomatic disease". However, the term "psychogenic" usually implies that psychological factors played a key causal role in the development of the illness. The term "psychosomatic" is often used in a broader way to describe