Well, note something - the article in question does not verify any known cases of maggots. Instead, it reports that parents got a letter warning them that such could happen.
A warning that thing can happen does not imply that thing ever actually happens!
I am not at all surprised that a school administration sent around a note with reports that would get parents' fears and dander up: "OMG! Kids are snorting stuff! They'll get nose maggots and die and civilization will end if this is not stopped!!!1!"
[video=youtube_share;LI_Oe-jtgdI]http://youtu.be/LI_Oe-jtgdI[/video]