World Health Organization (WHO), specialized agency of the United Nations, established in 1948, with its headquarters at Geneva. WHO admits all sovereign states (including those not belonging to the United Nations) to full membership, and it admits territories that are not self-governing to associate membership. There are 193 member nations. WHO is governed by the World Health Assembly, consisting of representatives of the entire membership, which meets at least once a year; an executive board elected by the World Health Assembly; and a secretariat headed by a director-general. There are regional organizations in Africa, the E Mediterranean, SE Asia, Europe, the W Pacific, and the Americas. WHO worked to eradicate smallpox, has made notable strides in checking polio, leprosy, cholera, malaria, and tuberculosis, and sponsors medical research on tropical and other diseases. WHO has drafted conventions for preventing the international spread of disease, such as sanitary and quarantine requirements, and for reducing smoking, and has given attention to the problems of environmental pollution. WHO is also authorized to issue global health alerts and take other measures to prevent the international spread of health threats.

Public-health agency of the UN, established in Geneva in 1948 to succeed two earlier agencies. Its mandate is to promote “the highest possible level of health” in all peoples. Its work falls into three categories. It provides a clearinghouse for information on the latest developments in disease and health care and establishes international sanitary standards and quarantine measures. It sponsors measures for the control of epidemic and endemic disease (including immunization campaigns and assistance in providing sources of pure water). Finally, it encourages the strengthening of public-health programs in member nations. Its greatest success to date has been the worldwide eradication of smallpox (1980).

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