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Asked by to Bethany, Hannah, Keith, Peter, Ramya on 13 Jun 2014. This question was also asked by .
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Keith Grehan answered on 13 Jun 2014:
That’s quite a tough question because it is often difficult to figure out exactly when a person first contracted a disease. I don’t know if they are really the fastest but both the Ebola virus and Marburg virus can cause death very quickly after catching it, Marburg can potentially kill within 2 weeks! This is part of what makes them such scary diseases, but it also helps to stop them spreading as they kill their victims so quickly that the disease has less opportunity to infect a new person.
As far as I know all cases of both these diseases have been linked to contact with wild animals mostly through “bush meat” (people hunting wild animals to sell as food) in Africa. They are also both linked to bats, some experiments have shown us that bats can carry Marburg virus but don’t seem to get sick so we think that these are probably the source of these virus most likely when someone ate a bat that was carrying Marburg (so try to avoid eating bats!).
Ebola and Marburg are very closely related and are both in a family of viruses called the Filoviridae (File-O-Vir-a-day 😉 ), they are also part of a bigger group of viruses that all cause disease that looks similar called the hemorrhagic fever viruses and they are all pretty nasty.
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Bethany Dearlove answered on 13 Jun 2014:
From the point of view of a disease it’s actually not sensible to kill your host too soon (if at all), as that decreases the chance of being able to spread and infect more individuals. Killing the host dramatically decreases the chance of survival – and diseases, just like us as humans, want to survive and give rise to the next generation. Often the worst diseases for fatalities are ‘newly emerging’ ones – these are diseases that haven’t infected humans before (or not in a long time), and not only does our immune system system struggle, but we don’t know anything about the disease to be able to treat it. Both of the viruses that Keith mentioned fall into this category. This is where sequencing and the work I do might come in useful, because we might be able to see what the disease is ‘like’ and base an initial treatment on how we would treat that.
It’s also worth mentioning that many diseases aren’t actually fatal in normal, healthy people on their own – but under certain conditions can rapidly take over and end up being fatal. This could be because the immune system is being overwhelmed by something else, or a downside of a treatment for something completely unrelated. For example, Clostridium difficile is a bacteria which will quite happily live in the gut with no problems. However, antibiotics for another infection (say, an ear infection) can kill off the protective good bacteria in the gut, allowing the C. difficile to take over and cause diarrhoea, or more serious complications like damage to the bowel, requiring surgery.
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Peter Elliott answered on 15 Jun 2014:
Keith and Bethany heave covered much of what I’d say but I’ll build on Bethany’s answer. In people who are suffering from HIV (Human Immunodeficiency Virus) their immune system which would otherwise keep them healthy is directly targeted. Your body can only keep fighting for so long until it can do no more and gives up. Then another disease causing bacteria, virus etc can come along and it is the 2nd infection that actually kills even a simple cold could be fatal and in a short space of time.
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