Although VZV has been detected in autopsies of nervous tissue, there are no methods to find dormant virus in the ganglia of living people. Unless the immune system is compromised, it suppresses reactivation of the virus and prevents shingles outbreaks. Why this suppression sometimes fails is poorly understood, but shingles is more likely to occur in people whose immune systems are impaired due to aging, immunosuppressive therapy, psychological stress, or other factors. Upon reactivation, the virus replicates in neuronal cell bodies, and virions are shed from the cells and carried down the axons to the area of skin innervated by that ganglion. In the skin, the virus causes local inflammation and blistering. The short- and long-term pain caused by shingles outbreaks originates from inflammation of affected nerves due to the widespread growth of the virus in those areas.As with chickenpox and other forms of alpha-herpesvirus infection, direct contact with an active rash can spread the virus to a person who lacks immunity to it. This newly infected individual may then develop chickenpox, but will not immediately develop shingles.The complete sequence of the viral genome was published in 1986. Diagnosis
If the rash has appeared, identifying this disease (making a differential diagnosis) requires only a visual examination, since very few diseases produce a rash in a dermatomal pattern (sometimes called, by doctors on TV "a dermatonal map").
Emboli often have more serious consequences when they occur in the so-called "end circulation": areas of the body that have no redundant blood supply, such as the brain and heart. Venous
Assuming a normal circulation, an embolus formed in a systemic vein will always impact in the lungs, after passing through the right side of the heart. This will form a pulmonary embolism that will result in a blockage of the main artery of the lung and can be a complication of deep-vein thrombosis. The most common sites of origin of pulmonary emboli are the femoral veins. The deep veins of the calf are the most common sites of actual thrombi. Paradoxical (venous to arterial)
In paradoxical embolism, also known as crossed embolism, an embolus from the veins crosses to the arterial blood system. This is generally found only with heart problems such as septal defects  (holes in the cardiac septum) between the atria or ventricles. The most common such abnormality is patent foramen ovale, occurring in about 25% of the adult population, but here the defect functions as a valve which is normally closed, because pressure is slightly higher in the left side of the heart. Sometimes, for example if a patient coughs just when an embolus is passing, it might cross to the arterial system. Direction
The direction of the embolus can be one of two types:
Anterograde
RetrogradeIn anterograde embolism, the movement of emboli is in the direction of blood flow.