They'd have to have quarantine camps and say someone's kid was sick, those parents would try to protect them and keep them at home and in the process cause the spread to worsen. Nobody would want to be near anyone sick, not even some doctors, so it would be difficult for the infected to get food and supplies without infecting others.

Nobody could work to earn money. Society would collapse because production of food and other goods would end and desperate people would turn to criminal behavior to survive. Rural areas would be flooded with city dwellers trying to find food and places to hunt/gather etc. leading to more crimes like murder to protect your own food sources, homes, and property.