Hindawi Publishing Corporation Journal of Parasitology Research Volume 2011, Article ID 214174, 19 pages doi:10.1155/2011/214174 Review Article Parasites or Cohabitants: Cruel Omnipresent Usurpers or Creative “Eminences´ Grises”? Marcos A. Vannier-Santos1, 2 and Henrique L. Lenzi3 1 Laborat´orio de Biomorfologia Parasit´aria, Centro de Pesquisas Gonc¸alo Moniz, Fundac¸˜ao Oswaldo Cruz (FIOCRUZ), Rua Waldemar Falc˜ao 121, Brotas, 40295-001 Salvador, BA, Brazil 2 Instituto Nacional para Pesquisa Translacional em Sa´udeeAmbientenaRegi˜ao Amazˆonica, Conselho Nacional de Desenvolvimento Cient´ıfico e Tecnol´ogico/MCT, Rio de Janeiro, RJ, Brazil 3 Laborat´orio de Patologia, Instituto Oswaldo Cruz, Fundac¸˜ao Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, RJ, Brazil Correspondence should be addressed to Marcos A. Vannier-Santos,
[email protected] Received 20 January 2011; Accepted 6 April 2011 Academic Editor: Bernard Marchand Copyright © 2011 M. A. Vannier-Santos and H. L. Lenzi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper presents many types of interplays between parasites and the host, showing the history of parasites, the effects of parasites on the outcome of wars, invasions, migrations, and on the development of numerous regions of the globe, and the impact of parasitic diseases on the society and on the course of human evolution. It also emphasizes the pressing need to change the look at the parasitism phenomenon, proposing that the term “cohabitant” is more accurate than parasite, because every living being, from bacteria to mammals, is a consortium of living beings in the pangenome.