Final answer:
International health threat assessments are conducted by the World Health Organization (WHO), a United Nations agency responsible for global health leadership and monitoring health trends.
Step-by-step explanation:
International health threat assessments are primarily conducted by the World Health Organization (WHO), which operates under the United Nations. The WHO is tasked with providing leadership on global health matters, shaping health research agendas, and monitoring worldwide health trends. This agency plays a critical role in addressing and responding to international health emergencies, such as disease outbreaks and pandemics.
The information about the health of populations and the state of health care systems around the world is made available through the WHO's regular updates and reports. Knowing which institution is responsible for such assessments helps in understanding the sources of global health data and the strategies developed to address health challenges.