Condom use is associated with a 30 percent reduced risk of contracting herpes simplex virus 2, also known as genital herpes, U.S. researchers said.

Emily T. Martin of Children's Hospital Research Institute and the University of Washington in Seattle and colleagues analyzed data from six studies to assess the effectiveness of condom use in preventing genital herpes.

The studies included 5,384 Herpes simplex virus 2-negative individuals -- average age 29 -- at baseline for a combined total of 2,040,894 follow-up days.

More than 66 percent of those who took part in the six studies were male, 60.4 percent were white, 94.1 percent were heterosexual and most reported no prior sexually transmitted diseases.

A total of 415 of the individuals acquired herpes simplex virus 2 during follow-up period.

"Consistent condom users -- 100 percent of the time -- had a 30 percent lower risk of herpes simplex virus 2 acquisition compared with those who never used condoms," the authors said in a statement. "Risk of herpes simplex virus 2 acquisition decreased by 7 percent for every additional 25 percent of the time that condoms were used during anal or vaginal sex."

The risk of acquiring the virus increased significantly with increasing frequency of unprotected sex acts, the study said.

The study appears in the Archives of Internal Medicine.