When treatment is less effective, free-riding is less severe and a DU's optimal screening may actually increase with its opponents level. However, as treatment becomes more effective, optimal screening levels are strictly decreasing in the other DU's allocation: free-riding takes full effect. As the number of DUs increases, so does the opportunity to free-ride. This means optimal screening will decrease and disease prevalence will increase as the number of DUs increases. Therefore, in a purely symmetric environment increasing unit autonomy may adversely affect disease prevalence: authority for screening should be centralized. 