The World Health Organization (WHO) works to build a healthier future for all people worldwide. Operating through offices in over 150 countries, WHO staff work with governments and partners to promote the highest level of health. They fight diseases like flu, HIV, cancer and heart disease. WHO also works to ensure safety of air, water, food and necessary medicines. Headquartered in Geneva, Switzerland, WHO supports countries' health coordination and objectives. Some areas of focus include health systems, disease prevention across life stages, noncommunicable diseases, communicable diseases, and emergency preparedness. Past successes include eradicating smallpox worldwide by 1980 and nearly eliminating polio from most regions by 2005.