![]() The slave trade, which flourished for three and a half centuries from about 1500, brought new parasites to the New World from the Old World ( 58) in more recent times, the spread of human immunodeficiency virus HIV and AIDS and the immunodepression associated with these conditions has resulted in the establishment of a number of new opportunistic parasitic infections throughout the world ( 5). The development of settlements and cities facilitated the transmission of infections between humans, and the opening up of trade routes resulted in the wider dissemination of parasitic infections. Heirlooms are the parasites inherited from our primate ancestors in Africa, and souvenirs are those that we have acquired from the animals with which we have come in contact during our evolution, migrations, and agricultural practices. ![]() For the purpose of this review, the parasites that infect humans can be classified as heirlooms or souvenirs. Sometime, about 150,000 years ago, Homo sapiens emerged in eastern Africa ( 254) and spread throughout the world, possibly in several waves ( 252), until 15,000 years ago at the end of the Ice Age humans had migrated to and inhabited virtually the whole of the face of the Earth, bringing some parasites with them and collecting others on the way. Human evolution and parasitic infections have run hand in hand, and thanks to the spinoffs from the Human Genome Project, we now know much more about the origins of the human race than ever before ( 197). HUMAN EVOLUTION, MIGRATIONS, CIVILIZATION, AND PARASITIC INFECTIONS In particular, the spread and present distribution of many parasites throughout the world has largely been the result of human activities, and the advent of AIDS has added a new chapter to the history of parasitology. There is, however, much more to the history of human parasitology than this, and our understanding of parasites and parasitic infections cannot be separated from our knowledge of the history of the human race. Since most of these parasitic diseases occur mainly in the tropics, the field of parasitology has tended to overlap with that of tropical medicine, and thus the histories of these two fields are intertwined. Many of these are rare and accidental parasites, but we still harbor about 90 relatively common species, of which a small proportion cause some of the most important diseases in the world, inevitably, these are the ones that have received the most attention. This review is concerned with the major helminth and protozoan infections of humans: ascariasis, trichinosis, strongyloidiasis, dracunculiasis, lymphatic filariasis, loasis, onchocerciasis, schistosomiasis, cestodiasis, paragonimiasis, clonorchiasis, opisthorchiasis, amoebiasis, giardiasis, African trypanosomiasis, South American trypanosomiasis, leishmaniasis, malaria, toxoplasmosis, cryptosporidiosis, cyclosporiasis, and microsporidiosis.ĭuring our relatively short history on Earth, humans have acquired an amazing number of parasites, about 300 species of helminth worms and over 70 species of protozoa ( 9). Thereafter, the history of human parasitology proceeded along two lines, the discovery of a parasite and its subsequent association with disease and the recognition of a disease and the subsequent discovery that it was caused by a parasite. The systematic study of parasites began with the rejection of the theory of spontaneous generation and the promulgation of the germ theory. ![]() Our knowledge of parasitic infections extends into antiquity, and descriptions of parasites and parasitic infections are found in the earliest writings and have been confirmed by the finding of parasites in archaeological material. Humans are hosts to nearly 300 species of parasitic worms and over 70 species of protozoa, some derived from our primate ancestors and some acquired from the animals we have domesticated or come in contact with during our relatively short history on Earth.
0 Comments
Leave a Reply. |