• Question: How (scientifically) could the plague have started?

    Asked by OkayOkay to Rachel, Nicholas, David on 16 Nov 2015.
    • Photo: Rachel McMullan

      Rachel McMullan answered on 16 Nov 2015:

      Hi
      That’s actually quite a complicated question. There are several different types of plague but I guess you mean the one that causes Black death. This is bubonic plague and it is transferred to humans by fleas which lived on infected rats.
      Its important to remember that the plague only became a big problem when people started living close together in big cities and the living conditions meant that they could easily spread it to other people. Also at the same time people started travelling and trading with other countries so infected rats onboard ships could spread the disease to other countries.

    • Photo: Nicholas Pearce

      Nicholas Pearce answered on 16 Nov 2015:

      Hey,

      A new disease can start when something changes slightly and this allows it to infect humans. Normally this change takes place in the DNA – germs can easily trade DNA with each other and this allows them to ‘evolve’ much faster, so they can evolve to infect new creatures and humans.
      The plague could have started when the disease evolved to infect humans as well as the fleas on the rats.

    • Photo: David Nunan

      David Nunan answered on 17 Nov 2015:

      Hey,

      Scientists have discovered that the bubonic plague started in China more than 2,600 years ago and then spread to Europe in 1348, carrie by rats on ships leaving China.

      The plague bacteria live in the blood of animals which is ingested by fleas. Once inside the flea in reproduces in the flea’s stomach, blocking its digestive tract and starving it. This causes the flea to bite more often and look for more animals to feed off, hence why it started infecting humans.

      Dogs are actually immune to the plague bacteria, but unfortunately cats are not 🙁

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