Emergence of Infectious Diseases in the 21st Century

As of 2008, mankind is confronted by 346 generic infectious diseases, distributed in a seemingly haphazard fashion across 220 countries. An average of three new diseases are described every two years – and a new infecting organism is published every week ! Over 1,600 human pathogens have been reported, each with a specific set of phenotypic, genomic and susceptibility characteristics which must be confronted by diagnostic laboratories and clinicians. The pathogens are in turn confronted by 276 generic anti-infective agents and 67 vaccines – marketed under 10,493 proprietary names.

Table 1, below, lists the major infectious diseases and pathogens which have been reported since 1972. Many conditions on this list (ie, Lyme disease, Legionellosis, Cyclosporiasis) are in fact old diseases which were only “discovered” when technology permitted us to recognize their presence. This is also true of many “new” pathogens, which could only be discovered because of the advent of molecular biology and other sophisticated laboratory techniques.

Perhaps the most striking development in this regard has been the explosion in “new” viral respiratory pathogens: Acanthamoeba polyphaga mimivirus, Bat reovirus, Human Bocavirus, Human Coronavirus HKU1, Human Coronavirus NL63, Human CoV 229E, Human CoV OC43, HRV-A, HRV-B, HRV-C, Human metapneumovirus, Karolinska Institutet virus, New Haven Coronavirus, Small Anellovirus, Tioman virus, Torque tenovirus and Washington University polyomavirus.

Another trend in this regard has been the discovery of infectious etiologies for “non-infectious” diseases: Kaposi sarcoma, peptic ulcer, cervical cancer, Whipple’s disease, to name a few.

Paradoxically, while technology has allowed us to discover and treat new diseases and pathogens, it has also contributed to the evolution of the diseases themselves. Broad-spectrum antibiotics, immunosuppressive drugs, prosthetic and transplantation surgery have each created a niche for opportunistic pathogens. Indeed, each breakthrough in the prolongation of human life and ability to treat heretofore fatal diseases is inevitably followed by an interesting list of Infectious Diseases challenges. On a broader scale, the scope of Infectious Diseases will be increasingly challenged by societal pressures related to overpopulation, air travel, global warming, conflict, famine, deforestation and bioterrorism.

As of 2008, GIDEON is the only Infectious Diseases program which follows the status of new diseases, outbreaks, antimicrobial agents, vaccines and pathogens. An ongoing summary of GIDEON content is available here.

Table 1: Major Infectious Diseases reported since 1972

YearAgentDisease
1973RotavirusRotavirus disease
1975Parvovirus B19Fifth disease
1976Cryptosporidium parvumCryptosporidiosis
1977Ebola virusEbola
1977Legionella pneumophilaLegionellosis
1977HantavirusHemorrhagic fevers
1977Campylobacter jejuniCampylobacteriosis
1980T-lymphotrophic virusT-cell leukemia
1981Toxigenic S. aureusToxic shock syndrome
1982E. coli O157:H7Hemorrhagic colitis, HUS
1982HTLV-IIHairy cell leukemia
1982Borrelia burgdorferiLyme disease
1983HIVAIDS
1983Helicobacter pyloriPeptic ulcer disease
1985Enterocytozoon bieneusiMicrosporidiosis
1986Cyclospora cayatenensisCyclosporidiosis
1988Human Herpes 6Roseola infantum
1988Hepatitis E virusHepatitis E
1989Ehrlichia chaffeensisEhrlichiosis
1989Hepatitis C virusHepatitis C
1989Guanarito virusVenezuelan hemorrhagic fever
1992Bartonella henselaeCat scratch disease
1993Sin nombre virusHantavirus pulmonary syndrome
1994Sabia virusBrazilian hemorrhagic fever
1995Human herpesvirus 8Kaposi sarcoma
1999Nipah virusNipah virus disease
2003SARS CoronavirusSARS

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