Oral herpes. The most common symptom of oral herpes, caused by the herpes simplex virus, is cold sores. Oral herpes can also cause fever and muscle aches. Mouth sores most commonly occur in children aged 1-2 years, but they can affect people at any age and any time of the year.ral herpes causes. Herpes simplex is a DNA virus that causes sores in and around your mouth. Two herpes subtypes may cause these sores. 1  Herpes simplex virus type 1, or herpes-1, which causes around 80% of cases of oral herpes infections. 2  Herpes simplex virus type 2, or herpes-2, which causes the rest.
The main symptoms of viral gastroenteritis are watery diarrhea and vomiting. Other symptoms of gastroenteritis include headache, fever, chills, and abdominal pain. The symptoms may appear within hours or a few days of infection. They usually last for 1 to 2 days, but may last as long as 10 days.
Gastroenteritis caused by noroviruses tend to occur more frequently during the winter months, but can strike at any time of year. After being infected with a norovirus, people have a temporary immunity, which usually lasts no more than about 14 weeks. People with types B and AB blood are better protected from infection and illness compared to those with type O.