What disease is caused by the Norwalk virus?

The Norwalk virus is primarily associated with causing a highly contagious gastrointestinal illness, often referred to as viral gastroenteritis. This illness is characterized by symptoms such as diarrhea, vomiting, nausea, and stomach cramps. It spreads easily from person to person and can be transmitted through contaminated food and water or by touching surfaces contaminated with the virus.

The high contagiousness and the gastrointestinal symptoms are key aspects of how Norwalk virus outbreaks occur, particularly in communal settings such as cruise ships, schools, and nursing homes, where close contact between individuals is common. Thus, the selection of a highly contagious gastrointestinal illness as the correct answer accurately represents the nature and impact of infections caused by this virus.