What is the disease commonly known as fever blisters?

The disease commonly known as fever blisters is specifically attributed to the herpes simplex virus, often referred to as herpes simplex virus type 1 (HSV-1). This virus is the causative agent behind the development of painful, fluid-filled blisters typically around the lips and mouth area. While the term "cold sore" is also frequently used to describe these lesions, the underlying viral infection is specifically herpes simplex.

Fever blisters usually appear during times of stress, illness, or exposure to sun and can be contagious, as they can spread through direct contact with the lesions or through saliva.

The other options listed do not accurately describe fever blisters. Shingles is caused by the varicella-zoster virus and presents with a different type of rash. Chickenpox is also caused by the varicella-zoster virus and primarily affects children, leading to an itchy rash and fever. While "cold sore" is indeed synonymous with fever blisters, it's important to recognize that the more clinical name for the underlying cause is herpes simplex virus. Thus, herpes simplex is the most precise choice for the disease in question.