Sentence:  Super-lice are bad news for most of us, but not for nit clinics, which are fast expanding. ... Then it is time for phase two, which involves a heat treatment, blasting hot air at my skull to dehydrate the eggs and eradicate the remaining offenders. This machine, rather like a high-tech salon hairdryer, is at times slightly scalding but not more painful than using a pair of hair straighteners. Finally, any <WSD>nitty</WSD> survivors are meticulously combed out, strand by strand. 
Meaning of the word marked with <WSD> tags:  Full of nits.