Tom Catena is the only full-time doctor at the Mother of Mercy Hospital - an off-grid, poorly supplied building located in the conflict-stricken Nuba Mountains.
The region lies in southern Sudan, and is regularly bombed by the government, which says the mountains are sheltering rebels.
The area is incredibly difficult to access by road, meaning medical supplies are scarce, and treating the thousands of patients who pass through the hospital with horrific shelling wounds is a daily struggle.
On call 24 hours a day, seven days a week, Dr Catena receives patients who have often walked for a week to reach him - despite the hospital not even owning an X-ray machine.
The original 80-bed hospital has now expanded to 435 beds, with more than 40 nurses. Dr. Catena has also just hired another doctor to expand the hospital’s capacity, and says, despite the daily danger, he cannot bring himself to leave.
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Dr Catena is the winner of the 2017 Aurora Prize for Awakening Humanity.