No amount of training can prepare you for this kind of prayer request. You just do what Jesus would do and bank heavily on the grace of God that something will happen. The bulk of our time is spent teaching and praying for their needs. You just wade out into the crowd and pray for everyone and everything. They may ask for a blessing to be prayed over their children or that devils be cast out of family members.
Malaria is a common problem.
People may have cancers and wounds or strange diseases such as leprosy. Sometimes their ailments could be cured with the simplest antibiotics if only they were available. One case that particularly moved us was a child from a village of lepers that we were visiting. She had been severely burned down her side from the armpit to the knee. It looked as if someone had spread a half-inch of thick, black, crisp, burnt marshmallow down her side.