Sept 12 (Reuters) - Tostan, a small Senegalese aid group credited with launching a grass roots campaign to abolish female circumcision in West Africa, will be awarded the $1.5 million Hilton Prize in New York on Wednesday. Here are some facts on Tostan and on the award. * The Hilton Prize is the world's largest humanitarian prize and has been awarded each year since 1996 by the Conrad N. Hilton Foundation established by the late hotel entrepreneur. Past winners include Doctors Without Borders and the International Rescue Committee. * Tostan was one of nearly 250 nominees for the prize, to be awarded in New York at a ceremony attended by U.N. Secretary-General Ban Ki-moon. * Tostan uses traditional song, poetry, theatre and dance in indigenous African languages to teach poor, rural communities in Senegal, Guinea, Gambia, Mauritania and Somalia about human rights, democracy, health, literacy and microcredit skills. It is due to start work in Djibouti and has also been active in Sudan, Mali and Burkina Faso. * One of its greatest achievements has been to encourage thousands of women to speak out against female genital cutting, long a taboo subject in Muslim West Africa. The practice has been abandoned in 2,336 communities in Senegal, 298 in Guinea and 23 in Burkina Faso where Tostan has been active. * Molly Melching, a U.S. citizen, founded Tostan in 1991 after setting up a centre in Dakar to educate street children using language and culture familiar to them -- the village songs, dance, stories and theatre that are part of the fabric of life in rural Senegal. Tostan's paid staff are almost exclusively African.