One big problem was the Eurasians who spent too long in sub-Saharan Africa had a tendency to come down with mysterious diseases, which were almost invariably fatal.
It had since been recognized that these diseases included malaria, dengue fever, yellow fever, and African sleeping sickness. But this was not known as the time, nor was it known that they are transmitted by bites from infected insects. Hence, there were no known ways of preventing the illness and, of course, no treatments. Furthermore, Eurasians had no immunities to these diseases and had a tendency to drop like flies when outbreaks occurred. Africans often got sick, but they didn’t die as often.
These diseases meant that Arabs, Turks, and Europeans who wanted to trade with sub-Saharan Africa for gold, slaves, ivory, or whatever preferred to stay close to the coasts.
It is not a coincidence that the European scramble for Africa started in the 19th and early 20th centuries . This was the period where treatments and methods of preventing tropical diseases began to be developed.
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