E.D.
Freeze 'em!
My girlfriend (and her housemate and three children) had a horrendous lice outbreak last summer. They tried a lot of the OTC remedies with no luck. It just kept on getting worse.
Then, they did mayonnaise treatments 2 x day, lice combed twice a day, vacuumed a few times a day, and put all bedding and clothing/soft toys/pillows into the drier and froze the smaller stuff, many times a week. This was to stop the risk of reinfection because lice eggs are tough little buggers.
When they went into full blown lock down mode, it was very successful. *My* philosophy? Take tiny bugs very, very seriously until there is zero risk for reinfection.
The mayonnaise / comb trick is really effective.