HIV/AIDS clearly represents one of the greatest challenges for preventive medicine in modern China. There are at least 1 million HIV positive individuals at present, and this figure may reach 10 million by the year 2010. However, the situation is not hopeless. In particular, the SARS epidemic provided an important learning experience and a key to the future battle against HIV/AIDS in China. Firstly, it revealed some important deficiencies in the medical and political infrastructure. Secondly, and perhaps crucially, it captured the attention of the international community and China's top leadership (28) . This may indicate tentative acceptance of the comprehensive response needed to combat the nation's greatest public health challenge. In some ways, Thailand can be seen as a role-model for HIV prevention within developing countries. Thailand has been particularly successful in reducing new HIV infections among prostitutes and military recruits with their 100% condom program (6) , and this approach may be appropriate for China. Either way, there will be many obstacles in controlling the epidemic, not the least of which will be to change public perceptions of HIV and raise awareness of preventive measures. Whether the Chinese government can muster the resources needed to keep its bold promises is also unknown. What is certain is that China now faces a serious epidemic in the new millennium, and one which will pose numerous challenges for public health and preventive medicine. Emerging zoonotic diseases: An opportunity to apply the concepts of nidality and one-medicine The use of animals as sentinels of human disease revolves around the concept of nidality. That is, an agent of disease occupies a particular ecologic niche and alterations in that niche will change the function of that agent relative to traditional host-agent-environment relationships. Nidality is a derivation of the root word nidus. Nidus is defined as a nest or breeding place, particularly a place where microbes such as bacteria, fungi, viruses, as well as other organisms and larger parasites, are located and multiply. Application of the concept of nidality and development of prevention strategies has most frequently been associated with military campaigns and interruption of tick-borne infections. Modern usage of the phrase “one-medicine” was popularized in the United States and Europe by Calvin Schwabe and the concept is attributed to Rudolph Virchow. It is applied today to the study of zoonotic disease and interventions in rural agricultural communities that share close living arrangements between people and their families, their pastoral work environment, and the animals for which they care. Integration of the two concepts of one-medicine and nidality provides an opportunity to apply a systems approach (i.e. general systems theory) to dealing with emerging zoonotic diseases in today’s global agricultural and industrial settings. The use of animals as sentinels of human disease revolves around the concept of nidality. That is, an agent of disease occupies a particular ecologic niche and alterations in that niche will change the function of that agent relative to traditional host-agent-environment relationships (1) . Nidality is a derivation of the root word nidus. Nidus is defined as a nest or breeding place, particularly a place where microbes such as bacteria, fungi, viruses, as well as other organisms and larger parasites, are located and multiply. Application of the concept of nidality and development of prevention strategies has most frequently been associated with military campaigns and the interruption of tick-borne infections (2) .