In the densely populated adjacent tribal areas. None in Kruger so far.

Source

Every single person I know who has come down with Malaria in Kruger over the years has a) been a staff member and b) caught the disease in their home villages outside the park, or on vacation in Mozambique. The one exception I can think of is a guide who most likely was infected in the Satara staff village.

Bottom line is that the chance of catching malaria in Kruger as a tourist is miniscule. Anybody who finds that risk worrisome should not go anywhere near a South African road, including those in Kruger. The number of traffic fatalities on Kruger's roads far exceeds the the number of malaria deaths (zero, most years). Or perhaps even avoid the country completely, given the crime rate. Over 40 tourists have been assaulted and robbed over the past few weeks, and that's only the cases that have made the headlines.

Johan