• Question: Do you think once you cure a disease, it will by then change to become immune to your cure?

    Asked by milanbassi to PB, Paul, Lyn on 21 Jun 2013.
    • Photo: Peter Balfe

      Peter Balfe answered on 21 Jun 2013:

      It can and does happen, but if you’ve had an acute infection (one you’ve recovered from), your immune system has a memory which will kick in and protect if you’re re-exposed,- that’s how vaccines work. But there are a lot of infections out there, and a related but different microbe might not be recognized, and could cause a new illness. Classically we mention to 200+ different viruses which cause the common cold, you could be immune to 199 of them, and still get ill!

    • Photo: Ee Lyn Lim

      Ee Lyn Lim answered on 21 Jun 2013:

      Cancer certainly does. That’s why sometimes when a person goes to get treatment for cancer, it goes away for a few years, and then it comes back again! That’s because not all the cells in a tumour are the same, there are some which can be killed by a certain type of treatment, but there are other cells that won’t be killed by that treatment but can be killed by another type.

      Cancer patients often get given one or two types of of treatment, then if the tumour shrinks and disappears we say that the treatment ‘worked’. But we can never see if there was just a handful, maybe 5 or 10 cells that were immune to that treatment and survived! In a few years, those 5 or 10 cells will have grown into another huge tumour, and this time ALL the cells will be immune to that treatment, so we can’t use the same treatment again.

      This is why we can’t invent just one miracle cure for all cancers – we can just invent as many types of treatment as we can, so that whatever the cancer cells are immune to, we always have something else to try.

    • Photo: Paul Waines

      Paul Waines answered on 25 Jun 2013:

      Hi milanbassi- if a disease is cured in one person, it does not mean that it could not go on to become immune (or resistant) to this cure elsewhere. Bacteria and viruses are incredibly good at evolving very quickly, and finding ways to fight these cures- this is what makes them so tricky.
      The only disease that we have actually made extinct is Smallpox, so when you think about how many diseases exist, this shows how difficult they are to deal with!

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