The Varicella zoster virus causes chickenpox in children and shingles in adults.
When the virus attacks as shingles, one of its distinguishing characteristics is that it only affects one side of the body. (As shown in the link and verbally identified by a doctor I spoke to). This happens because the nerve cells themselves are infected - and are partitioned on different sides of the body.
At first the rash appears similar to the first appearance of hives; however, unlike hives, shingles causes skin changes limited to a dermatome, normally resulting in a stripe or belt-like pattern that is limited to one side of the body and does not cross the midline. Zoster sine herpete ("zoster without herpes") describes a person who has all of the symptoms of shingles except this characteristic rash.
My question is: What is the name of the category of viruses that affect only one side of the body?