NOVA: JOURNEY TO PLANET EARTH Ecosystem Disruption and Emerging Infectious Diseases | |||||
DISEASE
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PATHOGEN
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GEOGRAPHIC LOCATION**
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HOST, SOURCE or RESERVOIR
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VECTOR
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ECOSYSTEM DISRUPTION
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Malaria
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Plasmodium spp. (protozoa)
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Lake Victoria, East Africa --Kenya, Uganda Tanzania (endemic)
Nairobi, Kenya (epidemic)
Peruvian mountain jungles & Iquitos, Peru (epidemic: increase from 1500 cases/yr to 165,000) |
Mosquitos & infected humans; Mosquito larvae in water sources |
Anopheles (mosquito)
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Endemic in tropical & subtropical rural zones; Rural fishing economy in decline due to raw sewage, agricultural runoff, overfishing Mobilization to urban areas; People bring malarial parasite and mosquitoes; Lack of sanitation & clean water Clear cutting forests & Overcrowding in urban areas with adjacent agriculture provide ideal conditions for breeding mosquitoes |
Dengue Fever
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Dengue Virus Flavivirus
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Iquitos, Peru
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Humans, monkeys
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Aedes aegypti ('urbanized'
mosquito)
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Human encroachment Mosquito breeds in
stagnant water found in manmade containers
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Cholera
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Vibrio cholerae (bacteria)
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Bay of Bengal Dakka, Bangladesh (endemic)
Coastal fishing village to Lima, Peru (1991) to S.America to N.America (epidemic) |
Water contaminated with human feces; Zooplankton (copepods) carry the bacteria (symbiosis) |
None
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Monsoons (floods); Increases in water temperature with plankton blooms; Overcrowding In Peru, El nino of 1990-92 warmed waters; Lack of sanitation and clean drinking water; Subsequent travel, commerce & tourism spread disease |
Yellow Fever
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Yellow Fever Virus Flavivirus
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Peru
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Humans, monkeys
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Aedes aegypti ('yellow
fever' mosquito)
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Human encroachment (ecotourism, airtravel,
commerce); People move virus and mosquitoes to other parts of the world;
Mosquito breeds in stagnant water found in manmade containers
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Oyster diseases(e.g., dermo, MSX)
Lesions & death in fish; Diarrhea & memory loss in humans |
Perkinsus marinus (dermo) Haplosporidium nelsoni (MSX) (both protozoa) Pfiesteria (toxic algae) and terrestial-source fungi?? |
Chesapeake Bay Crisfield, Maryland
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Brackish warm water
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None known
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Runoff of land-based pollution?? (agricultural
wastes, sewage, pesticides, industrial effluents, etc.)
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West Nile Fever (Encephalitis)
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West Nile Virus Arbovirus
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Africa to New York to contiguous United
States
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Birds (crows, blue jays, raptors, etc.)
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Mosquito
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Air travel with stowaway virus-carrying
insects??
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NOTE: The last 30 years has seen an upsurge
in waterborne and insectborne diseases. Estimates of 250 million cases of water-related
diarrhea annually with 3-5 million deaths per year (20-30,000 per day), the
majority of whom are children. Lack of clean drinking water and basic public
hygiene and sanitation practices are at the root of the problem.
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