Shingles Contagious Period and Diagnosis

Shingles is contagious and can be spread from an affected person to babies, children, or adults who have not had chickenpox or have not had the chickenpox vaccine. But instead of developing shingles, these newly infected people develop chickenpox. Once they have had chickenpox, people cannot catch shingles (or contract the virus) from someone else. However, people who have been infected with chickenpox have the potential to develop shingles later in life.

Shingles is contagious to people who have not previously had chickenpox or have not had the chickenpox vaccine, as long as there are new blisters forming and old blisters healing. Similar to chickenpox, the time prior to healing or crusting of the blisters is the contagious stage of shingles. Once all of the blisters are crusted over, the virus can no longer be spread and the contagious period is over.

The clinical appearance of shingles, with characteristic painful blisters localized to the region of a specific nerve on one side of the body, is usually sufficient to establish the diagnosis. No diagnostic tests are typically required. However, particularly in people with impaired immune function, shingles may sometimes not display the characteristic clinical pattern. In these cases, samples from the affected area may be tested in a laboratory, either by culturing the tissue or blister drainage for growth of the virus or by identifying the genetic material of the virus.