After having a fever for three days, my brain is a little garbled but I've managed to piece together this much.

1) My daughter's teacher and two other school staff went to a conference in Malaysia the second to last week of the term.

2) At the conference they were exposed to a "bad flu".

3) They were given flu prevention medicine and sent happily back to school.

4)Three days later my daughter was sick with a horrible flu. 

5)When I went in the last day of school to drop some things off the secretary told me her son was sick.

6)My son and I got the flu about two days after my daughter- fever, horrible head-ache, respiratory hacking, extreme aches and pains and fatique.

7) Half of my daughter's class did not show up at their end of the term parent/teacher conferences (due to illness?). 

My conclusion?  I think someone brought home a gift from Malaysia.