It’s not all about the seriousness of the infective agent, we have to take into account the immunity of the person and how strong the system is to keep the infection at bay. When Food we eat gets properly digested it is metabolized to seven different tissues (Dhatus) in the body. rasa, blood, muscle, fat, bone, bone marrow and reproductive tissues. The end product of good digestion is Ojas. When a person has strong digestion the transformation of food to different tissues and to Ojas happens properly. Good Ojas means strong immune system.