Out of Africa: The Slave Trade and the Transmission of Smallpox to Brazil, 1560-1831

Transmission of Smallpox to Brazil, I560-I831 Among the shock troops of the conquest of the Americas-the variety of infectious diseases introduced to the New World from Europe and Africa-smallpox was undoubtedly the leading killer. Certainly that was the case in colonial Brazil. We suggest that for much of the period between the beginning of European contact (15oo) and about 1831, when legal forms of the slave trade were ended, the primary source of smallpox contagion in Brazil was tropical Africa. Our argument may be summarized as follows: (1) Prior to the arrival of the first Europeans, smallpox (Variola major, the only one of three modern species of the virus then existing) was unknown in the future Portuguese colony, or in any other part of the Americas. (2) Because the pox survived in a community only as long as sufficient susceptibles existed to sustain the disease, and because of Brazil's persisting low population densities, Variola probably did not become endemic there until the nineteenth century. New outbreaks of the sickness, at least massive ones, therefore followed reintroductions from external sources, initially European but subsequently African. (3) As a prime New World importer of slaves, Brazil received regular infusions of potential African carriers of the disease, mainly from the Upper Guinea Coast (Senegambia) in the six-