Christina Aguilera's Back To Basics tour wraps up in a few days ... but she won't be able to perform in a couple of the remaining concerts in Australia!
Xtina has come down with a viral upper respiratory tract infection, a high fever and abnormal coughing ... the doctors have prescribed complete bed rest for the next few days.
Xtina sent a personal apology to her fans:
"Unfortunately, I have fallen ill with a bad flu virus. This is one of the best cities in the world to perform in and I am truly disappointed that I won't be able to share my show with you all. Thank you for all of the continued love and support and I hope to perform for you all again next time."
