Although the name of the disease is “poison”, it is not caused by a viral infection, but by an acute purulent dermal inflammation caused by a bacterial infection. The pathogenic bacteria is group A type B hemolytic streptococcus, mostly by the skin or mucous membrane wound and invasion. It can also be infected by bloodstream. Who is susceptible to this bacterial infection and develop dermatitis? 1, people with chronic lesions on the body surface: facial dermatophytosis is mostly caused by lesions on the nose, throat and ears, especially in patients with rhinitis and those who often dig their nose with their hands; lower limb dermatophytosis is mostly caused by tinea pedis or trauma to the lower limbs. 2, people with reduced immunity: people with malnutrition, alcoholism, gammaglobulin deficiency and nephrogenic edema have low immunity and are prone to this disease. 3.People who have suffered from dermatophytosis before: the disease can recur in the original site, called recurrent dermatophytosis. The disease can also cause chronic lymphedema over time. Chronic lymphedema that occurs in the lower legs also becomes rubbery legs. Therefore, it is important to actively treat even rhinophyma and tinea pedis, and not to develop the habit of digging your nostrils with your fingernails. When the immunity of the organism is reduced or when you suffer from nephrogenic edema, it is more important to keep the skin clean and intact.