Because malarial parasites can remain alive in the body of a victim for years, malaria, unlike yellow fever, should have encountered no great difficulty in reaching the Americas. On the contrary, quite probably the disease entered the hemisphere from nearly all points on the compass, and (again unlike yellow fever whose vector required importation) most etomologists and malariologists agree that probably many appropriate species of anopheline vectors, especially Anopheles gambiae and Anopheles funestus, were on hand to abet its spread.

Given these facts, one might reasonably expect a fairly straightforward account of malaria's arrival in and progress throughout the New World. Such, however, is not the case. It has been suggested (perhaps a bit naively) that malaria's distinctive symptoms should “mark it out sharply from other febrile illnesses,” making identification of the disease in historical records a relatively easy matter. But unfortunately malaria of the past is usually entangled in a bundle of fevers along with typhus, typhoid, even cholera infantum, and yellow fever, all of which are lumped together under the vague rubrics “remittent” or “intermittent” or “bilious” fever or a combination thereof such as “bilious remittent” fever connoting different ailments to different peoples during different periods. For these reasons the date of malaria's debut in all of the Americas, and especially North America, has been the subject of not always cool and reasoned debate.