Similarly, yellow fever is thought to have been brought to the Americas from Africa via the Atlantic slave trade. Because it was endemic in Africa, many people there had acquired immunity. Europeans suffered higher rates of death than did African-descended persons when exposed to yellow fever in Africa and the Americas, where numerous epidemics swept the colonies beginning in the 17th century and continuing into the late 19th century. The disease caused widespread fatalities in the Caribbean during the heyday of slave-based sugar plantation. The replacement of native forests by sugar plantations and factories facilitated its spread in the tropical area by reducing the number of potential natural mosquito predators. The means of yellow fever transmission was unknown until 1881, when Carlos Finlay suggested that the disease was transmitted through mosquitoes, now known to be female mosquitoes of the species "Aedes aegypti".