Civil society groups can also play roles complementary to health services, for example in the promotion of early reporting for diseases such as TB and sexually transmitted infections (STI), where delays in reporting currently constitute a major impediment to disease control, in ensuring quality of care (see later) and in providing community based care and rehabilitation. In relation to HIV/AIDS and TB the latter have become central elements of health management. These roles relate to both western and traditional health systems, and civil society organizations have sometimes played a role in strengthening three-way links between traditional and western health providers and communities (who use both health systems).