The term Emerging Infectious Diseases has become synonymous with newly recognised infectious diseases (such as SARS which appeared suddenly and unexpectedly in 2003) or with known infections that are increasing in incidence, increasing geographically (such as the dengue viruses causing dengue fever and dengue haemorrhagic fever) or expanding their host range (such as H5N1 avian influenza).
Three important factors in disease emergence have been recognised over the past two decades:
- 70% of all novel emerging diseases in man are zoonotic, originating in wildlife and domestic animals.
- With the enormous increases in air travel, the world has really become a vast global village with a potential for rapid inter-continental disease transmission
- The consequences of climate and global change include severe ecological disturbance with attendant movements of, and changed relationships between, people, wildlife and disease vectors. To face these increasing threats is one of the greatest challenges for the 21st Century.