Rotovirus--also spelled "rotavirus"-is a common, pediatric viral infection of the intestines. It is the most frequent cause of diarrhea in this country.   The rotovirus attacks the lining of the small intestine, and can cause much fluid and electrolytes loss through diarrhea, vomiting, and fever. Therefore, dehydration is a big danger with this illness.   The virus is spread through oral contact, to feces, to surface materials, so to help prevent the spread of this illness, be sure to wash hands frequently and properly clean surfaces that are used for diapering.   Rotovirus symptoms last between 3-10 days, but children are still contagious for 10-12 days after the start of diarrhea.