Belgian brains and Bantu muscle have thrust back the forest and checked the dread diseases (yaws, sleeping sickness, malaria) which sapped the Bantu's strength.
Pests that carry typhus, yellow fever, encephalitis, plague, yaws, cholera and tick fever could quickly slip out of human control.
An ancient problem, native or imported, has been yaws ( a disfiguring, nonvenereal disease caused by a spirochete much like that of syphilis).