Pathogens are extremely resourceful and possess mechanisms to adapt to new hosts and environments as well as to acquire new virulence traits. Host factors herd immunity, social behaviour and demographics. Environmental factors like the climate, deforestation and new technologies have an impact on the emergence of infections. The challenge is to contain an infection when it emerges but more importantly to prevent its emergence in the first place. As the emergence of an infection is complex and multifactorial, a multidisciplinary approach is required.
Health based strategies alone are insufficient.
Social, economic and environmental measures and the political will to implement appropriate policies are equally important. The emergence and re-emergence of infectious diseases has become not only a national issue but of international concern as well. The world it would appear has become much more vulnerable to global spread of both as well as old infections. The optimism expressed by health professionals and health organisations in the 1950s and 1960s has proven unfounded. Thus far from being over, the struggle to control infectious diseases has become increasingly difficult.