Meryl Streep has signed on to narrate a new documentary about health in Africa.

The Oscar winner will front Shout Gladi Gladi, directors Adam Friedman and Iain Kennedy's film about the debilitating condition fistula, which turns once healthy women into outcasts.

The documentary, being made in collaboration with The Freedom From Fistula Foundation, focuses on organisation founder Ann Gloag's experiences fistula sufferers in Kenya, Malawi and Sierra Leone.

The film also features rare appearances by philanthropist Melinda Gates and Nobel Peace laureate Wole Soyinka.

Announcing her involvement in the film on Thursday (26Feb15), Streep says, "'This powerful film attests to the igniting power of one woman, Ann Gloag, to set in motion hundreds of helping hands, doctors , nurses, caregivers, family and friends, to resuscitate the health and status of victims of fistula, and to give them back their lives."

An estimated two million women in Africa live with obstetric fistula, and another 100,000 develop the condition every year.