Parasitic animal diseases cause severe economic losses, and some may also be transmitted to human beings. They inflict traumatic, lytic, obstructive, intoxicative, allergenic and proliferative damage on the host, or cause loss of nutriment. In addition, the damage done by parasites may enable bacteria and other pathogens to enter the tissues and set up diseases. There are two main varieties of parasites: protozoa and metazoa. The main classes of protozoa are rhizopods, ciliates, flagellates and sporozoans. Metazoa comprise helminths (parasitic worms) of five separate groups: nematoda (roundworms), nematomorpha (gordian worms), platyhelminthes (flukes and tapeworms), acanthocephala (spiny-headed worms) and annelida (leeches); and arthropods, which can be pathogenic 'per se' or may transmit diseases (by virus, bacteria, protozoa and helminths). Main parasitic animal diseases include trypanosomiasis, liver fluke, blood fluke, trichinosis, toxoplasmosis, babesiosis, theileriosis, besnoitiosis, myiasis, leishmaniasis, mange, filariasis. Bacteria, viruses and fungi may also be parasitic.
The Encyclopedia of World Problems and Human Potential is a collaboration between UIA and Mankind 2000, started in 1972. It is the result of an ambitious effort to collect and present information on the problems with which humanity is confronted, as well as the challenges such problems pose to concept formation, values and development strategies. Problems included are those identified in international periodicals but especially in the documents of some 60,000 international non-profit organizations, profiled in the Yearbook of International Organizations.
The Encyclopedia includes problems which such groups choose to perceive and act upon, whether or not their existence is denied by others claiming greater expertise. Indeed such claims and counter-claims figure in many of the problem descriptions in order to reflect the often paralyzing dynamics of international debate. In the light of the interdependence demonstrated among world problems in every sector, emphasis is placed on the need for approaches which are sufficiently complex to encompass the factions, conflicts and rival worldviews that undermine collective initiative towards a promising future.
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