Unexpected Symbionts: What if Your Health could Benefit from Creatures you Normally Despise?

 

"Lice Capades" (2007). An absolutely wonderful episode of the "South Park" series. The world as seen from the viewpoint of lice. Fantastic. 

In Italy, there is a legend that says you may be cured of hepatitis b (jaundice) by eating lice. It is not just a vague legend, I personally know people who swear they were cured of jaundice by doing exactly that. Apparently, in the 1960s, there were still people who sold live lice packed in a small wafer (where they got the little beasties is anybody's guess). No trace of this story can be found on the Web nowadays, I can only relate it from what relatives and acquaintances tell me. But I have no reason to doubt that it was a common belief some 50 years ago, although it may have been limited to Tuscany, or perhaps only Florence. There are reports of people eating lice in other cultures and, of course, monkeys, apes, and other furry animals do that all the time. 

About this story, let me say that I am a big fan of evidence-based medicine and I am the first to doubt this story (and, also, I never had lice in my life). But, once you acquire the concept of "holobiont," you start reasoning that lice must have accompanied the human organism for millions of years. And, if they did, there has to have been some reciprocal adaptation and -- why not? -- mutual benefit. Of course, as a human being, you won't even remotely imagine that lice may be good for your health. But are you sure? 

At this point, you start searching the web and, surprise! (or maybe not), you immediately find an article titled "Unexpected Benefits from Lice" Look, this is serious stuff, evidence-based, not old folks' tales. And they say: 

Parasites such as lice have a role in the conditioning of a 'natural' immune system and reducing the likelihood of immune dysfunctions,

Of course, that's true for mice, but there is no reason to believe that it wouldn't work for human organisms, as well. Some people have said exactly that, "lice can be good for you." Maybe that's a bit optimistic but, surely, there is no reason to fall into hysterical reactions when dealing with lice in children. In some cases, lice may be bad for your health, but the little critters are not a major threat.

So, may lice be a symbiont rather than a parasite? As usual, the boundary between the two categories is fuzzy. Likely, no creature living inside the human holobiont is 100% parasitic. Most of those that lived with us for millions of years surely have at least some beneficial effects. And let me tell you just one thing: my mother-in-law holobiont had flatworms for most of her life. She turned 100 two months ago and she is in reasonably good health for her age. Would there be a correlation? At least, you can't rule that out!

You see how ideas interlock with each other and branch out generating new ones? Once you have the concept of holobiont, you have access to a whole new host of concepts. It is the beauty of the world we live in: truly Gaia takes many forms!