Emerging Infectious Diseases
A Key Role for Conservation Medicine
Andrew A. Cunningham
Emerging infectious diseases (EIDs) are diseases that have recently increased in incidence, have recently expanded in geographic or host range, are newly recognized, or are caused by newly evolved pathogens (Lederberg et al. 1992; Morse 1993; Daszak et al. 2000a). The term “emerging” was first used widely for human diseases in the 1970s (Sencer 1971; Moore and Robbs 1979), but achieved notoriety in the late 1980s following the discovery of a group of highly pathogenic diseases that included AIDS, hantavirus pulmonary syndrome, Legionnaire's disease, toxic-shock syndrome, multidrug-resistant bacterial infections, and Lyme disease (Krause 1992). The number of human EIDs continues to expand, with new pathogens discovered at an alarming rate and a number of older diseases resurging in incidence. These latter “reemerging diseases” include those caused by drug-resistant pathogens (e.g., tuberculosis in Europe and malaria throughout the tropics) and new threats from wildlife reservoirs (e.g., rabies in the eastern United States). Emerging infectious diseases have a high impact on human health, with some infections causing significant morbidity and mortality panglobally (e.g., drug-resistant malaria, AIDS) or on national or regional scales (e.g., dengue fever, Japanese encephalitis). Other EIDs cause more limited mortality but are a particular threat due to their extremely high case fatality rates and lack of available vaccines or therapy (e.g., Ebola and Marburg virus disease, Hendra virus disease, hantavirus pulmonary syndrome, Nipah virus disease).