Chicken pox, also known as varicella, is an acute, highly infectious disease caused by the varicella-zoster virus. It is characterized by a vesicular rash that may be accompanied by fever and malaise. The virus is usually spread through respiratory droplets from infected individuals. While chicken pox infections usually cause a mild, self-limiting disease in children, it can lead to more severe complications in adults and pregnant women. Recovery results in lifelong immunity against future chicken pox infections.