of bioptic telescopes for driving motor vehicles. (See also NOAH bulletin "Low Vision Aids".) There are a number of national support groups across the globe which come under the umbrella of the World Albinism Alliance. Epidemiology Albinism affects people of all ethnic backgrounds; its frequency worldwide is estimated to be approximately one in 17,000. Prevalence of the different forms of albinism varies considerably by population, and is highest overall in people of sub-Saharan African descent. Today, the prevalence of albinism in sub-Saharan Africa is around 1 in 5,000, while in Europe and the US it is around 1 in 20,000 of the European derived population. Rates as high as 1 in 1,000 have been reported for some populations in Zimbabwe and other parts of Southern Africa. Certain ethnic groups and populations in isolated areas exhibit heightened susceptibility to albinism, presumably due to genetic factors. These include notably the Native American Kuna, Zuni and Hopi nations (respectively of Panama, New Mexico and Arizona); Japan, in which one particular form of albinism is unusually common ; and Ukerewe Island, the population of which shows a very high incidence of albinism. Society and culture In physical terms, humans with albinism commonly have visual problems and need sun protection. Persecution of people with albinism Humans with albinism often face social and cultural challenges (even threats), as the condition is often a source of ridicule, discrimination, or even fear and violence. It is especially socially stigmatised in many African societies. A study conducted in Nigeria on albino children stated that "they experienced alienation, avoided social interactions and were less emotionally stable. Furthermore, affected individuals were less likely to complete schooling, find employment, and find partners". Many cultures around the world have developed beliefs regarding people with albinism. In African countries such as Tanzania and Burundi, there has been an unprecedented rise in witchcraft-related killings of people with albinism in recent years, because their body parts are used in potions sold by witch doctors. Numerous authenticated incidents have occurred in Africa during the 21st century. For example, in Tanzania, in September 2009, three men were convicted of killing a 14-year-old albino boy and severing his legs in order to sell them for witchcraft purposes. Again in Tanzania and Burundi in 2010, the murder and dismemberment of a kidnapped albino child was reported from the courts, as part of a continuing problem. The US-based National Geographic Society