My daughter picked them up somewhere and we played hell trying to get rid of them. Her long hair complicated matters, but we tried everything - lice shampoo, oil, we even put mayonaise in her hair, and combed it to death with the metal nit picks - and the Damn things kept coming back.
Finally we found professionals who drowned her hair in some oil blend and combed it out with metal picks and that got rid of them. The primary difference between what they did and what we'd been doing was they used a lot more oil. They also seemed to have a more organized method of combing to cover the whole head.
We live in a nice area - Everyone in our park keeps their trailer in good maintenance, and we make her bathe at least once a week, and use soap if we got it, but that doesn't always work.
Intresfingly, during all that time, even lying on the same pillow with her at times, I never got it. And no, I'm not bald.