Health systems need to be ready to handle crises affecting public health, thus minimizing damage to people, the community and the economy. Combating these changes will require collaboration and commitment between governments, corporations, foundations and nongovernmental organizations. An absolute concept of national sovereignty has been challenged by these events and by the need to secure collective defence against the emerging public health threats.

Emerging and epidemic prone diseases: new, highly contagious diseases, such as SARS and avian influenza, know no borders. In the last few decades, new diseases began emerging at an unprecedented rate of one or more per year. From 1973 to 2000, 39 infectious agents capable of causing human disease were newly identified. The development of microbial resistance is more worrying situation that could change the structure of morbidity and mortality in the world. .

Environmental changes and natural disasters: global environmental changes are associated with an increasing number and severity of events, such as tropical storms, floods, droughts, heat-waves, earthquakes that threaten food security or water contamination. In 2006, 134.6 million people were affected and 21 342 were killed by natural disasters, mainly in developing countries

Warmer temperatures influence the migratory patterns of wild birds and hence the potential for more unpredictable spread of viruses, like H5N1, that they carry.

Chemical, radioactive and biological terror threats: Anthrax-tainted letters sent through the U.S. postal system in 2001 and the release of sarin on the Tokyo subway in 1995 remind us that although chemical and biological attacks are rare, there are people ready to use this brand of terrorism.

For much of the world, 21st century life has become greatly dependant on chemical processing and

nuclear power. Public health security in turn relies on the safety of these facilities and the appropriate use

of their products. The threat of chemical spills, leaks and dumping, nuclear melt-downs, and chemical

weaponry invokes the notion of surprise attack or accidents, innocent victims and malicious or negligent

perpetrators and causes fears that may be disproportionate to the real risk.

International crises and humanitarian emergencies: Since the 1990s, the European Region has experienced a number of violent conflicts with vast political, social and human consequences.

Fighting in the Balkan countries in 1991-2002 is estimated to have killed more than 125 000 people and displaced up to 3 million.

Economic stability: public heath dangers have economic as well as health consequences. Containing international threats is good for economic well-being. With fewer than 10,000 cases, SARS cost Asian countries US $ 60 billion of gross expenditure and business losses in the second quarter of 2003 alone.

Strenghtening Health Systems. Functioning national health systems are the bedrock of international health security. Their objective is to provide the highest level of protection and care possible across the population. They are also the first line of surveillance for diseases, both infectious and chronic. Most diseases do not cause a “public health emergency of international concern”. But when a disease emerges which does pose such a threat, the alert and response required to prevent spread depend on an adequately resourced and staffed health system.