Parasites and Hosts

In an earlier draft of our script, one of our readers was quite confused by how a parasite can infect a host.  Not a good sign when the basis of your script, the driving hidden purpose, is lost on the reader.  If you have to explain your writing, basically, you have to rewrite it.  And we did.  And he was still confused.

So then, what was the source of the confusion?  Other readers didn’t have an issue or at least they had a sense of what was going on.  Part of the problem was related to how we as humans view parasites:  nasty worms or such, causing diseases, simply, to be avoided. I asked if that was the issue.

“No, not that. I can’t see how this works.”  Fair enough. Biology is a visual science.  I know, my background is biology and I taught the subject for twenty years. I don’t teach it anymore because those in charge seem to have forgotten that simple premise. And it’s getting worse, but I digress…

Parasites are actually simple critters, with complex life cycles and highly specialized adaptations to infect their host. They occur across every Kingdom and and when I taught the subject, I even  discussed with my students how viruses behave like genetic parasites.

But enough of that. I pondered the question, “How does this work?”  The idea of an alien species implanting a parasite into a human came to me when I thought about parasitoid wasps, which are alluded to in the script.  Basically, several species of parasitoid wasps lay their egg on an unsuspecting host, usually another insect, often a caterpillar.  The egg hatches, burrows into the insect and feeds on it until wasp larvae is fully grown.  The science is fascinating: the caterpillar goes about its business gorging on food, not realizing it’s just feeding a young wasp.

“Oh, okay,” said the reader.  “Then why two parasites for one host?” Well, I thought about an answer. “It’ll be explained in the sequel. Promise.”