Doing lick-lick to comfort the kos, the fungus can directly enter the parents, causing more severe fungal-infection. Soon the parent yukkuris also get moldy.The strong irritation urges the koyukkuris to do rub-rub with their parents, which speeds up the dispersal of the fungus. Little ones don't cry, let's do rub-rub with mommy, rub-rub...