Viruses and bacteria can persist on the ground, in the air, on various surfaces for differing amounts of time depending on the nature of the beast (or bug as it were) so there may not have to be dog-to-dog or even dog-to-kid contact. Hand washing and shoe removal are always good ideas but there may not be much you can do about it.
On the positive side, people and dogs too usually don't get reinfected with the same bug once they get over it the first time as their immune systems are now prepared for a second bout. Unless Jass or Keoki are immune-suppressed in any way, they ought to be fine here shortly.