Lessons from Troy

21 February 2017

Interview with

Caitlin Pepperell, University of Wisconsin-Madison

In some parts of the world mortality associated with childbirth can be as high as 50%. But this is not a new problem as Chris Smith hears from Caitlin Pepperell at the University of Wisconsin-Madison...


Caitlin: The story starts with Henrike Kiesewetter who’s an archaeologist and a physician examining a cemetery from the ancient city of Troy that dates back about 800 years. While she was examining a skeleton of a young woman, she found two nodules at the base of her ribs. The nodules are about the size of strawberries and they just look like chalky white material. Dr Kiesewetter thought that they were pieces of calcified lung from tuberculosis.

Chris: That would fit with the whole idea that individuals who have TB often do get calcifications in their lung tissue, don’t they? They would be sort of in the right anatomical position for that, although TB likes the top of the lung rather than the bottom, doesn’t it?

Caitlin: Yes, exactly. Although of course, things would easily have moved around in the intervening 800 years. So, she gave the nodules to an Archaeologist, William Aylward who is here at the University of Wisconsin-Madison and Dr Aylward contacted me because I have done a lot of work on evolution of tuberculosis.

Chris: So, you're handed by this archaeologist two lumps of chalky material about the size of strawberries. How did you proceed?

Caitlin: I'm not an ancient DNA expert. So, the first thing that I did was to enlist the help of an ancient DNA specialist so that we could recover DNA from the nodules and make a diagnosis. In this case, we got extraordinary amounts of ancient bacterial and human DNA.

Chris: Now, was this DNA from bacteria that could be in the environment? So, when this individual died and was buried, they could’ve colonised the body at that point or do you think these bugs were intimately linked to those lesions that would’ve occurred when that person was alive?

Caitlin: We think that they were from the lesions and from when the young woman was alive. The reason is that we also looked in the soil and did not find these bacteria. They're also bacteria that are well-known to cause disease in humans.

Chris: What were they?

Caitlin: So there are two species, Staphylococcus saprophyticus and Gardnerella vaginalis, both a mouthful. Staph saprophyticus is a common cause of urinary tract infections and Gardnerella vaginalis is part of the normal microbiome or bacteria that are normally found in the body, and also, causes a range of diseases including pregnancy complications.

Chris: So, do you think that’s what this was? Do you think these nodules were some kind of pregnancy complication?

Caitlin: I do. I think that she had an infection called chorioamnionitis which is an infection around the developing foetus and the placenta and it can cause disease to the foetus and loss of the pregnancy as well as disease in the mother. Her age at the time of death was estimated from her remains and she was thought to be between 25 and 35 years old at the time of death.

Chris: So why did she die?

Caitlin: We don’t know for sure, but I think given the amount of bacteria that was recovered from the nodules, she had a very severe infection and I think it’s quite likely that this infection is what led to her death.

Chris: What is important about this paper other than that it is extremely interesting and you have found this pathology from 800 years ago? What are the implications of this and what does it teach us?

Caitlin: It’s the first, really detailed look at pregnancy related infection from the archeological record. We know that complications at pregnancy are very important in the modern world and have been very important historically as well. So, in terms of learning about maternal health in the ancient world, I think it’s very significant. As far as the bacteria go, I think we learned quite a bit about how these two species of bacteria have evolved, how they changed and didn’t change over time. And this helps us to understand how disease-causing bacteria evolve in general.

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