Emerging Infectious Disease

An emerging infectious disease (EID) is an infectious disease whose incidence has increased in the past 35 years and could increase in the near future. Emerging infections account for at least 12% of all human pathogens. EIDs are caused by newly identified species or strains (e.g. SARS, AIDS) that may have evolved from a known infection (e.g. influenza) or spread to a new population (e.g. West Nile virus) or area undergoing ecologic transformation (e.g. Lyme disease), or be reemerging infections, like drug resistant tuberculosis. Of growing concern are adverse synergistic interactions between emerging diseases and other infectious and non-infectious conditions leading to the development of novel syndemics.

The U.S. Centers for Disease Control and Prevention (CDC) publishes a journal Emerging Infectious Diseases that identifies the following factors contributing to disease emergence:

• Microbial adaption; e.g. genetic drift and genetic shift in Influenza A
• Changing human susceptibility; e.g. mass immunocompromisation with HIV/AIDS
• Climate and weather; e.g. diseases with zoonotic vectors such as West Nile Disease (transmitted by mosquitoes) are moving further from the tropics as the climate warms
• Change in human demographics and trade; e.g. rapid travel enabled SARS to rapidly propagate around the globe
• Economic development; e.g. use of antibiotics to increase meat yield of farmed cows leads to antibiotic resistance
• Breakdown of public health; e.g. the current situation in Zimbabwe
• Poverty and social inequality; e.g. tuberculosis is primarily a problem in low-income areas
• War and famine
• Bioterrorism; e.g. 2001 Anthrax attacks
• Dam and irrigation system construction; e.g. malaria and other mosquito borne diseases