Even internal organs may be affected by zoster. Usually the diagnosis of zoster is based on the way the blisters look and pain on one side of the body. To be sure, the dermatologist may do a special test in which skin cells from a blister are examined under the microscope. If a certain type of cell damage is seen, this, combined with the location of the blisters and pain, gives the diagnosis. If there is still doubt, fluid-containing viruses can be examined and identified.
Results are usually available in several days.
If you have other medical problems or could have been exposed to AIDS virus, be sure to let your dermatologist know. Treatment of zoster would be different under these circumstances. The physician will ask questions about your medical history and may order certain tests, such as chest x-rays or blood studies, to make sure there are no other problems. The majority of people who develop zoster, however, are otherwise healthy. The virus that causes zoster can be passed on to others, but they will develop chicken pox, not zoster.