It is discovered that lice (head, genital, etc.) are actually self-aware, sentient, sapient beings, and as such, killing them is illegal because duh, that’s like totally murder and shit. So now when you get lice, you have to just leave it in there, unless you can find a volunteer’s body to transfer them to. This becomes a service that some people provide. The transfer process is time consuming and labor-intensive, and therefore inconvenient and expensive. ‘Cause you gotta get each nit onto a new hair safely, and that takes delicacy and precision. And time. And lice techs are paid by the hour.
Terrariums are created that can support ongoing, population-stable lice communities, and can also facilitate communication and cultural exchange between humans and lice. It turns out, lice are unbelievably cool and groovy people. The lice-human communication tech becomes portable, and not long after, the in thing to do is to harbor a lice colony, providing yourself as a living area and using the tech to communicate with your parasites. Who, as I said, are just really great fucking people. They are wise well beyond their humble status as vermin. And they have culture out the butt. It becomes unusual _not_ to harbor a lice colony familiar. Those who don’t are those who are allergic, or who aren’t good at carrying lice for whatever reason.
With the help of the communication tech, an agreement has been reached where lice will obtain consent prior to infesting a new host. So those who can’t support lice (or choose not to) won’t get infested without their consent. Lice become non-contagious. Or I mean, it can spread, they just have to obtain the consent of the new host. Which is impossible in most circumstances. So the lice just don’t spread like they used to in the old days. Like I said, they’re really cool people.
Hosting a lice colony can be less physically comfortable than not doing so, but it will enrich your life in all sorts of ways, and, assuming you take care of it, it will be a loyal, lifelong companion. So what do you say? Will you host a colony? I’ve got several available to choose from, all with ancestry and genetics and stuff. You won’t be getting mongrel herds from my showroom. And we’ll throw in the installation as part of the purchase price. I assure you, sir or madam, you won’t find a better deal anywhere else in town.