• Question: How do diseases kill?

    Asked by to Bethany, Hannah, Keith, Peter, Ramya on 16 Jun 2014. This question was also asked by .
    • Photo: Hannah Tanner

      Hannah Tanner answered on 16 Jun 2014:


      This is a really difficult question to answer. A person has a disease when there is anything wrong with them that stops them being 100% healthy. Diseases can be genetic (things you are born with like cystic fibrosis), they can be caused when your cells go wrong (like cancer), they can be caused by toxic substances get into your body (like poisoning) or they can be caused when a pathogen invades your body (infections with bacteria, viruses, fungi or parasites). Different diseases work in different ways and they don’t all kill you – some just make you mildly or moderately ill.
      I’ll concentrate a bit in infectious diseases which is when pathogenic (disease causing) bacteria, viruses, fungi or parasites invade.
      Firstly the pathogen has to get in to your body. Different pathogens get in in different ways. They can get in if your skin is damaged by a cut or graze, you can breathe them in, you can eat them in food, you can get bitten by insects or animals carrying pathogens.
      Secondly, once they are in, they have to avoid your immune system killing them. Some bugs hide inside your own cells, some make themselves look like your own cells, some keep changing their chemistry so your immune system can’t keep up, some actively destroy your immune cells.
      Thirdly, once they are inside and have avoided your immune system they need to replicate and make more copies of themselves.
      Once they are established, they can do some damage. It really depends on exactly which pathogen is causing the infection but these are some of the ways pathogens can kill you:
      Damage to your cells by making toxins (poisons).
      Damage to your cells by replicating inside and bursting them to get out.
      Some viruses can insert their DNA into your own cell’s DNA and can make your own cells cancerous.
      If the damage to your cells is in one particular organ like your liver it can stop that organ doing the work it needs to to keep you healthy and that can eventually kill you.
      If pathogen toxins get into your whole body they can poison your whole body and kill you.
      If the pathogen is damaging your immune cells it can make you much more likely to get other infections and die because your immune system is damaged.
      If your body’s immune system over-reacts to an infection it can start damaging your own cells and that can kill you .

    • Photo: Bethany Dearlove

      Bethany Dearlove answered on 17 Jun 2014:


      As Hannah’s answer shows – this is a really broad question, and there are many ways a disease can kill, often depending on the disease in question and the context (where is it, are there other diseases there too?).

      Were there any specific diseases you had in mind, that we might be able to tell you about in more detail?

Comments