Signs and symptoms of norovirus infection may start suddenly and include: 
Nausea
Vomiting
Stomach pain or cramps
Watery or loose diarrhea
Feeling ill
Low-grade fever
Muscle pain
 Signs and symptoms usually begin 12 to 48 hours after your first exposure to a norovirus and last 1 to 3 days. You can continue to shed virus in your stool for several weeks after recovery. This shedding can last weeks to months if you have another medical condition. Some people with norovirus infection may show no signs or symptoms. However, they're still contagious and can spread the virus to others.