Paleoparasitology of schistosomiasis.

Eighteen years ago, when we began our studies in paleoparasitology, the main question proposed was whether Schistosoma mansoni infection has been really introduced by African slave trade in South America or has it been present among indians before Columbus. Up to now the question remains without answer, but it is interesting to point to some old and recent arguments regarding schistosome infection in ancient times. In 1944, BF Magalhães and CB Dias (1944 Mem Inst Oswaldo Cruz 41: 363-367) discussed the origin of S. mansoni infection, reviewing the beginning of African slave trade in Brazil, and suggesting that the African origin was not so well demonstrated as written in some textbooks of parasitology. A clear and definitive answer could be achieved by the find of schistosome eggs in pre-columbian coprolites preserved feces in archaeological sites. Starting from that point, and to answer the question above, we began our studies in paleoparasitology, and we have examined up to now 1,100 coprolites dated from 30,000 years ago to colonial times, collected in South American archaeological sites. Ancylostomiasis, trichuriasis, and oxyuriasis have been found as intestinal infection among prehistoric indian population, but no S. mansoni eggs were found in human coprolites (LF Ferreira et al. 1988 Paleoparasitologia no Brasil, PEC/ENSP/FIOCRUZ, Rio de Janeiro, 158 pp). However, negative data in paleoparasitology must be viewed cautiously, and some findings of S. haematobium and S. japonicum in human archaeological material are important for this discussion. MA Ruffer (1910 Br Med J I: 16) found S. haematobium eggs in an Egyptian mummy of the Twentieth Dinasty, dated of 3,200 years before Christ (BC). A Cockburn et al. (1977 J Ass Med Can 117: 415-418) and P Lewin (1977 Am J Dis Ch 131: 349-350) also recorded S. haematobiun eggs in tissues of Egyptian mummies. Recently, AM Deelder et al. (1990 Lancet 24: 724) developed a technique to detect schistosome antigen in mummified tissues, and RL Miller et al. (1992 BMJ 304: 555-556) discussed the paleoepidemiology of schistosomiasis, only regarding S. haematobium in ancient Egypt. S. japonicum eggs were found in China, in a 2,100 old male corpse (S Lingbiao & O Hung 1981 Acta Acad Sin 3: 1), and schistosome infection was recorded also by O Wei (1973 Lancet 2: 1198) in a lady of the Han Dinasty (206 BC-220 AD). Before all these records, WL Paraense (1959 Rev Bras Mal D Trop 2-3:105-117) pointed that the distribution of the three parasite species of man must be viewed through the principles of geographical speciation, not allowing the exclusion of a separate center of speciation for each species: S. japonicum in the East, S. haematobium in the Ethiopic region, and S. mansoni in the Neotropical region. In Europe, Africa, and the Americas there is no record of S. mansoni infection and the question presented remains to be answered. Coprolite examination, and molecular biology techniques applied to paleoparasitology (molecular paleobiology) are the possible means to get a comprehensible understanding of the origin and ancient distribution of these three species of Schistosoma that infect man.