Last year, Al Jazeera reported on two teenage girls who suffered appalling injuries when acid was thrown in their faces on their way to school in Afghanistan.

It was one of a series of attacks blamed on the Taliban.

Shamsia Husseina and her sister Atifa returned to school in January, determined to continue their education.

But new threats have left them living in fear for their lives once again.

Al Jazeera's Teresa Bo reports.