The Cottages run all manner of lab tests to see if they can figure out what exactly is wrong with Dan. I guess they're not totally in support of House's guess-and-check-whoops!-we-made-it-worse methods. Cameron suddenly exclaims that, according to the DNA tests, House wins their little bet. Chase notes that Dan's mother isn't his biological mother, either.
The parents are talking to Cuddy about getting their son the hell out of the hospital and to another one with doctors who aren't assholes who freely order lumbar punctures. Good luck with that. House enters, sees them, and promptly calls them both idiots. Lying idiots. Adopted Dad says that might be true, but that House accused them of molesting their son. "Perfect," says Cuddy, since no other words are needed, really. House requests that the focus be taken off him and put back onto Dan's adoptive parents, who never told anyone -- including Dan -- about Dan's true genetic makeup, because they love Dan and they are his parents and that is all that matters. House says that when you're dealing with medical stuff, it isn't. Cuddy asks House exactly how he found out about all of this, and he has to admit that he totally stole their coffee cups. "You...can't do that!" says Cuddy, so shocked that she can't even think of a witty retort. House says that the issue at hand right now is Dan's family medical history, and how it's totally useless now. The parents say that the medical history they gave was everything they knew about Dan's biological mother, who gave him up when he was two weeks old. Cuddy says that seems perfectly reasonable to her. House asks if the biomom was vaccinated as a child. They say Dan was when he was six months old. They don't know about his biomom, though.
And now it's time for the CGI medical explanation segment of the program. The Magic School Bus Cam swirls around, following a nasty-looking spiky ball thing that is the measles virus. House voice-overs that before his vaccination, Dan got the measles. It made him sick, but he survived. We go inside the virus to a strand of DNA (which I don't think is accurate, since viruses only have RNA, although this graphic may very well be RNA and I just don't know how to identify a double helix), which snaps as House explains that, in a one-in-a-million freak occurrence, the virus mutates. Then it travels to his brain and hides for sixteen years before it resurfaces as subacute sclerosing panencephalitis. It's rare as hell, with only twenty cases in the US in the last twenty years, but that it can be treated as long as it's still in stage one with intraventricular interferon. This conflicts with everything I read about SSPE, which said it's always fatal, and quickly. Some remissions have been reported, but they were only temporary. Dan was better off with the MS and the lumbar punctures. The interferon treatment involves "shoving a spike into his brain," as Chase puts it, which they can't do unless they have a confirmed diagnosis. But that can't get that because all the drugs they've given him for their diagnosis mistakes will create false readings on future tests. "So the wrong treatment kills any hope of the right diagnosis. WHY do people LIE to me?" House says, like, WHY do you treat people for things without being certain that it's what they actually have? Foreman says that there is another way.