My daughter just had thrush in her month a month ago. It is contagious and you have to be careful to not let other kids share items. A basic search on the internet (using "thrush contagious") will provide you with a lot of substantiated evidence that thrush IS contagious. Here is a link with precautions that should be taken:
http://www.uihealthcare.com/topics/dental/dent4380.html
"To prevent thrush, keep these tips in mind:
be careful, when changing diapers, not to transfer thrush from the mouth to the diaper area or from a diaper rash, caused by thrush, to the mouth
follow good hygiene, including careful hand washing and disposal of nasal and oral secretions
notify child care workers that a child has thrush, so extra precautions can be taken
sterilize all bottles, nipples, pacifiers, and teething toys by boiling for 5 minutes, then boil everything again once the thrush has disappeared
eat yogurt or take acidophilus capsules when taking antibiotics
treat any vaginal yeast infection that develops during pregnancy as soon as possible
if you smoke, ask your healthcare provider for ways to quit
see your dentist every 6 to 12 months, especially if you have diabetes or dentures
brush and floss your teeth after every meal
limit the amount of sugar and yeast-containing foods you eat (such as bread, beer and wine)
See your healthcare provider if thrush does not go away on its own or tends to recur."
Good luck!
A.