TUESDAY, Aug. 22, 2006 (HealthDay News) -- Changes in sexual behavior may be reducing the number of Americans infected with the herpes simplex virus type 2, which causes most cases of genital herpes.
Researchers also found that the prevalence of herpes simplex virus type 1 infection -- which is typically spread during childhood via nonsexual contact -- is also falling.
"The most exciting finding is that we looked at the proportion of Americans infected with the herpes simplex virus and found a decrease over the past decade," said lead author Dr. Fujie Xu, from the U.S. Centers for Disease Control and Prevention. His team reported the findings in the Aug. 23-30 issue of the Journal of the American Medical Association.
Overall, the number of Americans aged 14 to 49 who tested positive for herpes 2 infection fell by a relative rate of 19 percent between 1988 and 2004 -- from a prevalence of 21 percent in the late 1980s and early 1990s to 17 percent 10 years later, the researchers reported.
Herpes simplex virus type 2 causes most genital herpes and is one of the most common sexually transmitted infections. Herpes simplex virus type 1 is usually transmitted non-sexually but is a principal cause of genital herpes in some developed countries.
In the study, researchers at the CDC compared data from the National Health and Nutrition Examination Surveys (NHANES) from two time periods: 1988-1994 and 1999-2004. Together, the surveys included more than 20,600 Americans aged 14 to 49.
The drop in herpes type 2 infections between 1988 and 2004 was particularly significant among teens, the researchers found. The number of people aged 14 to 19 who tested positive for herpes simplex 2 dropped from 5.8 percent in the 1988-1994 survey to just 1.6 percent 10 years later.
"The decrease appears to be due to changes in sexual behavior," Xu said. These changes may include careful partner selection, condom use and choosing oral sex over vaginal sex, the researchers noted.
Xu's team also found that the proportion of people with herpes simplex virus type 1 also decreased -- from 62 percent in 1988-1994 to 57.7 percent in 1999-2004, a relative decline of 6.9 percent. This decrease was not unexpected and is due to improvements in living and hygiene conditions, the researchers said.
However, the number of people affected by genital infections linked to type-1 herpes infection appears to be rising. The authors explained that, because fewer Americans are getting infected with the type 1 virus during childhood, they may be more susceptible to sexually acquired genital infections later on.
While there has been a drop in the number of Americans infected with either form of the virus, herpes still affects millions of people in the United States, Xu pointed out. "Overall, the prevalence is 17 percent -- that means one in six Americans are still infected with this virus," she said.
Increased efforts to stop the spread of herpes could bring those numbers down, however. "The surest way to stop the spread of any sexually transmitted disease is abstinence," she said. "Consistent and correct condom use can reduce, but not eliminate, the risk of transmission," she added.
In addition, treatment for herpes can also help prevent the spread of the virus, Xu noted.
One expert thinks these new findings confirm how prevalent herpes is in the United States.
"The important message from this study is how common herpes is and that most people don't know they have it," said Dr. Cynthia Krause, an assistant clinical professor of obstetrics/gynecology at Mount Sinai School of Medicine, in New York City. "The decline is a small percent compared to the incredible prevalence of the infection.
Another expert believes much more can be done to curb infection rates.
"There is no herpes-control program in the United States," said Dr. Jeffrey D. Klausner, director of STD Prevention and Control Services at the San Francisco Department of Public Health. "I hope that by highlighting that tens of millions of Americans have herpes infections, it will get people to think about what kind of control programs may be necessary."
Klausner believes steps such as screening, treatment, education and counseling can all help reduce the rate of herpes infections.
"There is evidence that condom use is being recognized as a very effective means to prevent STDs. So people may be using them more," Klausner said. "It is [also] possible that younger people are having fewer partners," he added.
However, Klausner doesn't believe abstinence has had any effect. "I would not attribute anything to the abstinence-based campaigns. They have been shown repeatedly not to be effective," he said.
There's more on herpes at the U.S. National Institute of Allergy and Infectious Diseases.