Full medical travel insurance, inclusive of air evacuation from remote areas, is highly recommended. Be aware that some insurance policies may not cover activities deemed to me hazardous, for instance paragliding or scuba diving.
When travelling to South Africa we always recommend that you speak to a local travel consultant to ensure that you have all of the right documentation and cover. These policies and procedures may change and therefore your local operator can not be held responsible in cases of medical emergency.
There are a couple of fantastic resources for both such as Just Landed that can guide you through the process.