Final answer:
More than 65% of adults show serologic signs of infection with HSV-1, which primarily causes oral herpes and often remains asymptomatic.
Step-by-step explanation:
More than 65% of adults have serologic evidence of HSV-1 infection. HSV-1, or Herpes Simplex Virus Type 1, primarily causes oral herpes, which manifests as cold sores or fever blisters around the lips. The infection is highly contagious, with a notable proportion of the US population carrying the virus. Even though a significant number of individuals are infected with HSV-1, many remain asymptomatic, showing no overt physical symptoms of the infection. Additionally, HSV-1 can have periods of latency when residing in the trigeminal nerve ganglia and may reactivate under stress or certain environmental conditions.