Rickettsiae are microorganisms that resemble bacteria but which grow only within susceptible cells, including human cells, - not in cell-free culture media, as bacteria do. The rickettsiae are mainly parasites or symbiotes of arthropods - especially lice, mites, and ticks; from these hosts the rickettsiae may spread to man and domestic animals, causing serious disease.
Epidemics of louse-borne typhus are still a threat. Among the other major groups of rickettsioses, murine typhus, scrub typhus, and Rocky Mountain spotted fever commonly occur in endemic areas.
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.
Non-profit, apolitical, independent, and non-governmental in nature, the UIA has been a pioneer in the research, monitoring and provision of information on international organizations, international associations and their global challenges since 1907.