“Fever Blisters”, or “Cold sores” are caused by infection, almost always, with the Herpes Simplex 1 virus. Herpesvirus infestations are present in 50% of the population, usually causing little disturbance. The symptoms on first exposure depend on the Age the virus is first acquired.
NEONATAL Herpes can be extremely serious, due to the immaturity of the infant immune system. Herpes acquired in CHILDHOOD, or Primary herpetic Gingivostomatitis, can cause very dramatic FEVER, with blisters in the mouth, that lasts for a week to 10 days, causing lots of misery and hand-wringing but having a good outcome.
I had one such case early in my pediatric residency at Walter Reed Army Hospital, a young French boy named Didier Dupont. He screamed with pain, and wouldn’t eat or drink. His parents thought that he was going to die, and that I saved his life, neither of which was true. My roommate and I lived in the same housing complex as the Duponts, and enjoyed many fine french meals with them, one of the few positive events to result from an encounter with Herpes Viruses.
The first acquaintance with Herpes in ADULTHOOD produces outcomes ranging from no symptoms at all, to a flu like syndrome with mouth blisters. Many people have positive blood tests for herpes, but cannot recall any mucosal burning, blisters or pain, so Herpes can enter the body without producing memorable symptoms.
The Herpes 1 Virus gains entrance to the body through the lining of the lips, mouth or nose(or through broken skin), and travels up the local nerves to the cell body in the local Trigeminal ganglion. There it remains quietly, until some STRESS reduces the resistance, allowing it to awaken and travel back down the nerves to the “mucocutaneous junction”, where the skin thins out into the lining of the nose, mouth, or occasionally the eyes.
There it multiplies and forms painful blisters, or “cold sores”. Sunburning of the lips, a “cold”, or psychological strain are examples of the stresses that can trigger cold sores. Reduced resistance is the common factor.
The Acyclovir family of drugs is usually effective in treatment, and works by inhibiting DNA Polymerase. These oral medications can be given to curtail each episode, if cold sores are infrequent, or continuously to reduce the number of outbreaks.
Herpes 1 is a double stranded DNA Virus in a family that includes Herpes 2, Chickenpox, the EB virus of mononucleosis fame, and Cytomegalovirus, which is the bane of organ transplant recipients. A nasty Clan indeed, and very successful in evolutionary terms.