text: what is rotovirus?   rotaviruses are a genus of viruses belonging to the reoviridae family. seven major groups have been identified, three of which (groups a, b, and c) infect humans, with group a being the most common and widespread one. they cause vomiting and diarrhea and are the most common cause of severe diarrhea in children, killing about 600,000 children every year in developing countries (as of 2005). new vaccines have been shown to be safe and effective in 2006.