• Question: Why haven't pathogens developed over years to be able to survive for longer?

    Asked by to Bethany, Hannah, Keith, Peter, Ramya on 24 Jun 2014. This question was also asked by .
    • Photo: Bethany Dearlove

      Bethany Dearlove answered on 24 Jun 2014:


      This is a really great question. The truth is that they have developed over the years. They constantly mutate and change, although not all of those mutations will actually be useful to the pathogen. Some will be beneficial though, for example those that allow it to survive outside of a host for longer, or give resistance to a drug. As an example, norovirus mutates once every two to three weeks, allowing changes to accumulate very quickly. Quite a few of these mutations fall in the area of the genome that codes for the capsid, which is the part of the virus that comes into contact with the host cells – if the mutations cause the capsid to change shape, it might be able to evade the immune system for longer.

      The problem for pathogens is that we’re developing too – both in terms of our immune system, and how we give medical treatment. It’s a complex system, where both host and pathogen are constantly trying to gain the upper hand.

    • Photo: Keith Grehan

      Keith Grehan answered on 24 Jun 2014:


      A key thing to think about when wondering about how things evolve is to look at the pressure to change. if a strategy is successful then it is likely that it will stay that way until there is pressure to change.
      For most pathogens the short life and fast reproduction strategy that they use is working brilliantly, just think about how many different diseases there are and how widespread they are.
      So unless living longer gave one pathogen an advantage over others in terms of how much it could spread we probably wont see a pathogen evolving to live a long time.

Comments