Volume 1, Number 1—January 1995
Perspective
Factors in the Emergence of Infectious Diseases
Table 1
Infection or Agent | Factor(s) contributing to emergence |
---|---|
Viral | |
Argentine, Bolivian hemorrhagic fever | Changes in agriculture favoring rodent host |
Bovine spongiform encephalopathy (cattle) | Changes in rendering processes |
Dengue, dengue hemorrhagic fever | Transportation, travel, and migration; urbanization |
Ebola, Marburg | Unknown (in Europe and the United States, importation of monkeys) |
Hantaviruses | Ecological or environmental changes increasing contact with rodent hosts |
Hepatitis B, C | Transfusions, organ transplants, contaminated hypodermic apparatus, sexual transmission, vertical spread from infected mother to child |
HIV | Migration to cities and travel; after introduction,sexual transmission, vertical spread from infected mother to child, contaminated hypodermic apparatus(including during intravenous drug use, transfusions, organ transplants |
HTLV | Contaminated hypodermic apparatus, other |
Influenza (pandemic) | Possibly pig-duck agriculture, facilitating reassortment of avian and mammalian influenza viruses* |
Lassa fever | Urbanization favoring rodent host, increasingexposure (usually in homes) |
Rift Valley fever | Dam building, agriculture, irrigation; possibly change in virulence or pathogenicity of virus |
Yellow fever (in new areas) | Conditions favoring mosquito vector |
Bacterial | |
Brazilian purpuric fever (Haemophilus influenzae, biotype aegyptius) | Probably new strain |
Cholera | In recent epidemic in South America, probably introduced from Asia by ship, with spread facilitated by reduced water chlorination; a new strain (type O139) from Asia recently disseminated by travel (similarly to past introductions of classic cholera) |
Helicobacter pylori | Probably long widespread, now recognized (associated with gastric ulcers, possibly other gastrointestinal disease) |
(associated with gastric ulcers, possibly other | |
Hemolytic uremic syndrome (Escherichia coli O157:H7) | Mass food processing technology allowing contamination of meat |
Legionella (Legionnaires' disease) | Cooling and plumbing systems (organism grows in biofilms that form on water storage tanks and in stagnant plumbing) |
Lyme borreliosis (Borrelia burgdorferi) | Reforestation around homes and other conditions favoring tick vector and deer (a secondary reservoir host) |
Streptococcus, group A (invasive; necrotizing) | Uncertain |
Toxic shock syndrome (Staphylococcus aureus) | Ultra-absorbency tampons |
Parasitic | |
Cryptosporidium, other waterborne pathogens | Contaminated surface water, faulty water purification |
Malaria (in "new" areas) | Travel or migration |
Schistosomiasis | Dam building |
* Reappearances of influenza are due to two distinct mechanisms: Annual or
biennial epidemics involving new variants due to antigenic drift (point
mutations, primarily in the gene for the surface protein, hemagglutinin) and pandemic strains, arising from antigenic shift (genetic reassortment, generally between avian and mammalian influenza strains.)
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