Written by Joe Ballenger

Recently, we had a chance to do another awesome podcast with the wonderful guys at Mythwits. First, I should probably mention that this is a very casual podcast…which means it’s Not Safe for Work. Besides the Mythwits crew, we were joined by John Cmar who studies infectious disease at Sinai hospital in Baltimore, MD.

We got the chance to discuss how different parasites take control of their hosts, which is a topic I’ve always found interesting. In fact, it was reading about this topic in the book Parasite Rex which was a big part of getting me into entomology. Nancy tackled the question from an ecological standpoint, I tackled the question from a physiology standpoint, and Cmar took on the question from a medical angle.

I did want to give a brief summary, for those who may not want to listen to the NSFW podcast.

When a parasite gets into a host, it has exactly one goal: survive long enough to reproduce. They’re already living in an insane environment, but sometimes they need to get into another animal to complete that lifecycle. Sometimes that animal is an insect, other times it’s a human. However, many animals will facilitate the transfer to a new host by getting it’s host to act in an unusual way.

This can be extremely simple, or very complicated. The bubonic plague facilitates its spread by plugging the stomach of its flea vector, which makes it hard for fleas to eat. The fleas attempt to feed more often, and end up spreading the disease. Strepsipterans, on the other hand, force their hosts to congregate by introducing entirely new behaviors. There’s a lot of stuff between these two extremes, discussed in the podcast.

Often times, the parasites will take advantage of pre-existing patterns. In the example of Bubonic plague, the bacteria take advantage of a feeding behavior which is in place to avoid starvation. Some insect viruses disrupt the molting of their hosts to send them to the tops of trees, while the healthy ones are on the ground molting. How, exactly, this happens is discussed in the podcast.

There are even parasites which change behaviors in humans, as well. These include the rabies virus, Toxoplasma gondii, and African sleeping sickness. Although it’s still not understood how these parasites manipulate people, recent research is beginning to shed some light on these infections. Cmar, who is more qualified to talk about human disease than either of us, discussed these in the podcast.

So it was a great time, and a wonderful podcast. We’re hoping that we get to do another, and revisit this topic.