HSV-1 affects only humans. Oral ulcers are most common in children aged 1-2 years, but they can affect people at any age and any time of the year. Oral inflammation of HSV-1 is also known as herpetic stomatitis.
People infect HSV-1 by contacting infected saliva, mucous membranes or skin. Because the virus is highly contagious, most people infect at least one HSV-1 herpes subtype before adulthood.
After HSV-1 infects a person, it has a rather unique ability to perform three phases.
Stage 1 - Primary infection: The virus usually enters the skin or mucous membranes through small cracks or breaks and then regenerates. At this stage, oral ulcers, blisters, and other symptoms such as fever may occur.
The virus may not cause any ulcers and symptoms. People may not know that they have an infection. This is called asymptomatic infection.
Asymptomatic infections occur twice as often as symptoms.
Stage Two - Latency: From the site of infection, the virus moves to a large number of nerve tissue in the spine, called the dorsal root ganglion. There the virus replicates again, usually without any symptoms, and becomes inactive until it is reactivated by certain physical conditions (see stage 3).
Stage 3 - Relapse: When people experience certain stress (also known as triggering), emotional or physical, the virus may reactivate and cause new pain and symptoms. The following factors may cause or trigger recurrence: stress, illness, ultraviolet rays (including ultraviolet rays), fever, fatigue, hormonal changes (such as menses), immunosuppression, and trauma to previous sites or areas of the nerve that cause HSV infection.
