Two herpes viruses hide in your nerves, then flare for a lifetime
Herpes simplex comes as oral or genital disease, driven by HSV-1 and HSV-2. After an often harsh first outbreak with fever and swollen nodes, the virus retreats into nerve cells and returns in milder flares. Between 60 and 95 percent of adults carry at least one type, and there is still no vaccine or cure.
The name comes from an ancient Greek word linked to creeping, a nod to spreading blisters rather than to the virus's talent for hiding. HSV-1 usually infects the mouth, often in childhood, and HSV-2 usually the genitals, though either can cross over through contact with fluids or sores. Once inside, the virus travels up sensory nerves to the nerve cell bodies in a ganglion and stays there for life; the immune system never clears it.
Flare-ups can be set off by weakened immunity, stress or sunlight. A first episode may bring fever, muscle aches, swollen glands and headache, and blisters that burst into ulcers typically heal in two to four weeks, sometimes heralded by tingling or shooting pain. The virus can also strike fingers as whitlow, the eye as keratitis and the brain as encephalitis. Newborns, transplant recipients and people with AIDS face the gravest complications, and infection can occasionally be fatal.
Much transmission happens silently. Most people carry HSV-2 without knowing it, and in half of cases viral shedding occurs more than a week before or after a visible outbreak. Tiny breaks in skin or mucous membranes are enough for the virus to get in. As of 2003 an estimated 536 million people, about 16 percent of the world, had HSV-2, with higher rates among women and in developing countries; HSV-1 reaches 70 to 80 percent in poorer populations.
Antibodies from one infection offer partial protection: earlier HSV-1 seems to soften a later HSV-2 episode without preventing it. Avoiding sex is the surest defence against genital infection, condoms cut the risk, and an infected partner's daily antiviral lowers the odds further. Aciclovir or valaciclovir shorten and ease flares, and episodes usually grow rarer and milder over time.
Source: Herpes
