• Question: what is the parasites job

    Asked by 244parf44 to Claire, Franco, Koi, Linda, Mark on 18 Jun 2016.
    • Photo: Franco Falcone

      Franco Falcone answered on 18 Jun 2016:

      @244parf44

      A parasite has evolved to survive and maintain its own pool of genes. It does so at the cost of other living organisms, in which it can cause serious disease and suffering. While at the individual level a parasitic infection can be seen as a bad thing, at the population level, it can contribute to limit the size of a certain population of animals, keeping the ecosystem in balance, which in the end is a good thing for all partners involved. Mark has explained this much better elsewhere, so I won’t spend more time on this aspect.

      There is however increasing evidence that a low level of infection with some parasites also benefits the host, as it appears to protect them against certain allergic and autoimmmune diseases, and many scientists think that the relatively recent loss of parasites (e.g. hookworms) in the history of humans, due mainly to increased hygiene, is one of the reasons behind increasing numbers of people with allergies and diseases such as Type 1 diabetes, in combination with genes, viral infections, nutrition and environmental factors.
      It is all very very complicated and beyond the ability of one single person to comprehend, as there are so many factors involved, so maybe Koi’s ‘big data’ approach which she described elsewhere can help answer some complex of these very important questions.

    • Photo: Mark Booth

      Mark Booth answered on 18 Jun 2016:

      Hi @244par44

      I refer you to Franco’s answer below, my own answer elsewhere and may I add that I have never seen a gainfully employed parasite in my life. By definition they exploit their hosts rather than work for them.

    • Photo: Arporn Wangwiwatsin

      Arporn Wangwiwatsin answered on 19 Jun 2016:

      Hi 244parf44,

      By definition, parasites live at the cost of other living things… so what they do for a living will be around that concept. THe exact act might be feeding on body tissue, sucking up blood, stealing some nutrient, releasing eggs and juvenile parasites that might disrupt normal functions of the infected body… and many more. But as Franco mentioned, modern society have fewer contacts with parasites and that is thought to be not too good either.

      My current big data study is not focusing on this directly, but similar approach is trying to look at various ways that the parasites might be interacting with their hosts; for examples, we can look at how the parasites affect the community of bacteria within the host – we all do have bacteria inside our gut, and it’s still an open question how these bacteria work and what that means for our body (they don’t always cause diseases). Another way might be to look at molecules in blood and compare between people with and without parasites to get a clue of what the parasites might be doing to the body.

    • Photo: Linda Anagu

      Linda Anagu answered on 20 Jun 2016:

      @244parf44, parasites are exploitative organisms that maintain the ecosystem by limiting the number of certain animals and availability of nutrients. That is their job.

    • Photo: Claire Bourke

      Claire Bourke answered on 20 Jun 2016:

      Hi 244,
      a parasite’s job at a basic level is just like ours, to survive and fulfill it’s life cycle. In an evolutionary sense that goal is to pass on it’s genes to the next generation, but in a day-to-day sense a parasite living on or in the human body a parasite spends it’s time eating (nutrition), respiring, excreting, moving, growing, reproducing and sensing it’s environment; you might be familiar with these characteristics from your biology lessons as they are the 7 features of all living things.

      The especially interesting thing about parasites, as the other scientists have mentioned, is that in order to do these things they have to counter-act the processes in the human body that try to kill them or flush them out. As an immunologist I am interested in how they avoid being detected or killed by the immune system, which is no mean feat! The ‘job’ of evading the human immune system has kept parasites working hard for thousands of years of evolution; every time the parasite developed a new way of escaping, the immune system developed a new way to attack, then the parasite had to develop a new defense, and so on and so on…this process has meant that parasites and their human hosts have ‘co-evolved’, which is one reason why parasites and our immune systems are so specialised (and complicated!). So, even though parasites freeload off of their hosts and take their nutrients without providing any benefit in return, they have to work very hard to do this…as we find new and better treatments to kill parasites, they will have to work even harder!

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