Research published in the Journal of Infectious Diseases shows that fewer U.S. teens today have been exposed to the cold sore-causing herpes simplex virus type 1 (HSV-1) than adolescents in the past. By the time they become sexually active, their bodies lack the antibodies to fight off the virus.
HSV-1 and a related virus, herpes simplex virus type 2 (HSV-2), both cause lifelong infections with no known cure, that can go through dormant periods after an initial outbreak.
Most people contract HSV-1 in childhood, through skin-to-skin contact with an infected adult. HSV-2 is usually transmitted sexually.
"HSV-1 now is the predominant herpes strain causing genital infection," Dr. David Kimberlin, chair of infectious diseases at the University of Alabama at Birmingham School of Medicine explained to HealthDay News.
According to Kimberlin, the new findings suggest that almost 1 in 10 adolescents who, a decade ago would have already acquired HSV-1 and built up some immunity, may now encounter HSV-1 when they first become sexually active. That could leave them more susceptible to genital herpes than young people were in the past.
HSV-1 has been seen increasingly as the cause of genital herpes in industrialized countries, with one study revealing that up to 60 percent of genital herpes cases were due to HSV-1.
A shift by young people toward participation in oral sex might help explain the trend, experts said to WebMD, since the herpes virus can easily be transmitted from the mouth to the genitals.
“Every year the proportion of patients who get infected with HSV-1 through oral sex is increasing," Dr. Marcelo Laufer, a pediatric infectious disease specialist at Miami Children's Hospital said to Daily Mail.
The virus is usually passed through saliva, but in more recent years better hygiene may have kept the virus from spreading to young children, Laufer theorized to WebMD. That means that fewer children are now exposed and are producing antibodies against HSV.