Poultry that are raised in stressful, confined animal feeding operations (CAFOs) may be most likely to contract and transmit contagious diseases like avian flu. CAFOs are known for stressful, crowded and inhumane conditions that can negatively impact an animal’s health and welfare.  This is why large scale CAFO chicken manufacturers heavily vaccinate and medicate flocks more than healthier free run, naturally-raised poultry farms.