Chickenpox, or chicken pox, also known as varicella, is a highly contagious, vaccine-preventable disease caused by the initial infection with varicella zoster virus (VZV), a member of the herpesvirus family. The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over. It usually starts on the chest, back, and face. It then spreads to the rest of the body. The rash and other symptoms, such as fever, tiredness, and headaches, usually last five to seven days. Complications may occasionally include pneumonia, inflammation of the brain, and bacterial skin infections. The disease is usually more severe in adults than in children.

कांजण्या हा प्रामुख्याने लहान मुलांचा आजार आहे. हा आजार एकदा येऊन गेला, की परत होत नाही. पण काही व्यक्तींमध्ये हे विषाणू सुप्तावस्थेत राहतात आणि प्रौढावस्थेत 'नागीण' या रोगाद्वारे प्रकट होतात.व्हारीसोला झोस्टर या विषाणूमुळे हा रोग होतो,म्हणजे हा विषाणूजन्य आहे.