If the colony is small now, there may not be that much heat in the brood box to get the Apiguard working - although the weather has been warm in some parts of the country until now.
Were there signs of deformed wings or deformed bees in cells?
I have had a couple of cases where the colony has reduced in size dramatically around August/Spetember. This is as bee numbers reduce and varroa levels continue to increase causing parasitic mite syndrome. My colonies did survive after treatment and with a donation of a frame of sealed brood from a strong colony to get them going again as a bit of a kick start. I don't recall that the queens were any worse afterwards as a result of the colony collapsing.
I haven't heard much about CCD in the USA recently and I am sure that it was caused by inadequate treatment of varroa at the time. I do remember seeing poor advice to beekeepers about treating for varroa and their practice of open feeding where many hundreds of colonies were being overwintered in the middle of nowhere would have been a great way of transmitting diseases and varroa from bee to bee; a bit like taking the kids to a measles party.
I have noticed that in some colonies the brood pattern can get a bit 'ragged' before varroa treatment and improves afterwards. With Apigaurd and Apilife Var, the queen can go off lay for a few days initially.
May your bees read the same books as you do.
