Allergic purpura nephritis is due to systemic allergy, whether it is food, drug allergy can appear skin purpura, invade many systems, such as invade the gastrointestinal system, joints, etc., invade to the kidney can cause allergic purpura nephritis. Therefore, the root cause of allergic purpura nephritis is allergy, and infectious are two concepts. The so-called infectious disease is usually a disease caused by bacterial or viral infection. Allergic purpura is only food and drug allergy, there is no possibility of infection. So, strictly speaking, allergic purpura nephritis is not an infectious disease. The most direct manifestation of allergic purpura is purpura on the skin, in addition, some patients can invade the gastrointestinal tract, which can manifest as abdominal pain, joint pain, symptoms of skin, and also manifest as symptoms of nephritis.