The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. It is part of the U.N. Sustainable Development Group. WHO is headquartered in Geneva, Switzerland, with six semi-autonomous regional offices and 150 field offices worldwide. The WHO Regional Office for Africa is one of WHO’s 6 regional offices around the world. It serves the WHO African Region, which comprises 47 Member States with the Regional Office in Brazzaville, Republic of Congo. As the lead health authority within the United Nations (UN) system, WHO works with the Member States in the African Region and development partners to improve the health and well-being of people. The WHO's main areas of work include health sector development, combating diseases – infectious diseases like TB and HIV, and non-infectious diseases like cancer, diabetes and heart disease.