Norovirus infection is characterized by nausea, forceful vomiting, watery diarrhea, abdominal pain, and in some cases, loss of taste. General lethargy, weakness, muscle aches, headache, and low-grade fever may occur. The disease is usually self-limiting, and severe illness is rare. Although having norovirus can be unpleasant, it is not usually dangerous and most who contract it make a full recovery within a couple of days. The virus affects around 267 million people and causes over 200,000 deaths each year; these deaths are usually in less developed countries and in the very young, elderly and immuno-suppressed.