Genital Herpes caused by HSV-1 doesn’t often recur

(17 April 2003)

Genital herpes can result from either of two types of the herpes simplex virus (HSV type 1 and HSV type 2), and new research suggests that people infected with the HSV-1 type will experience less frequent recurrences of the disease.

HSV-1 typically causes facial cold sores. Recently, however, the virus has become a more frequent cause of genital herpes.

However, genital herpes still most commonly results from infection with herpes simplex virus 2, or
HSV-2.

Most of the time, HSV-1 and HSV-2 are inactive, or "silent," and cause no symptoms, but some infected people have periodic outbreaks of blisters and ulcers. Once infected with HSV, people carry the virus for life.

Dr Anna Wald and her colleagues at the University of Washington and the Fred Hutchison Cancer Research Center in Seattle report that 43% of people with genital herpes caused by HSV-1 don't experience another outbreak during the first year after infection.

And the rate of recurrence appears to decline over time, the authors note: Almost 70% of people with HSV-1 genital herpes did not experience another outbreak during the second year after infection.

This recurrence pattern is markedly different from that seen in people with HSV-2, Wald and her team note, suggesting that all patients with genital herpes should know which virus type caused their condition.

Knowing which virus is behind a person's outbreaks "has big prognostic implications," Wald explains. Based on these findings, Wald recommends that people with HSV-1 seldom have a need for daily suppressive therapy, a treatment designed to stave off future outbreaks. However, daily suppressive therapy is more likely to be useful for patients with genital herpes caused by HSV-2, Wald notes.

The authors obtained their findings by following 77 patients diagnosed with genital herpes from HSV-1. Half of the patients were followed for at least 736 days.

On average, the authors found that people experienced 1.3 recurrences of their herpes during the first year after infection, and 0.7 during the next year--a 50 percent decrease in recurrence rate.

In contrast, Wald and her team note that people infected with HSV-2 experience a recurrence rate five times that seen with HSV-1 during the first year after infection, and the rate of recurrence decreases at a much slower pace.

Just why the virus is causing more cases of genital herpes is unclear. However, due to improvements in hygiene and standards of living, people are no longer developing cold sores from HSV-1 when young leaving them open to acquiring the virus through sexual contact when older.

Ref
Wald A et al. Sexually Transmitted Diseases 2003;30:174-177.