What is the cause of purpura nephritis?

The cause can be bacteria, viruses and parasites and other infections caused by allergies, or for certain drugs, food and other allergies, or for plant pollen, insect bites, cold stimulation caused. Often related to the following factors:
1. infection: 1/3 cases before the onset of 1 to 4 weeks before the history of upper respiratory tract infection, common pathogens are: virus: Coxsackie, EB virus, adenovirus, varicella virus, rubella virus, hepatitis B virus. Bacteria: Salmonella, Legionella, hemolytic streptococcus and so on. Mycoplasma, amoeba, roundworm.
2, drugs: antibiotics, sulfonamides, isoniazid, captopril and so on.
3, food, fish, shrimp and crabs.
4, cold stimulation, plant pollen, eggs, mosquitoes, vaccination, animal feathers, paint and so on.