BIOLOGY & SCIENCE: article : Emerging Infectious Diseases

Thursday, March 12, 2009

article : Emerging Infectious Diseases

NOVA: JOURNEY TO PLANET EARTH Ecosystem Disruption and Emerging Infectious Diseases
DISEASE	PATHOGEN	GEOGRAPHIC LOCATION**	HOST, SOURCE or RESERVOIR	VECTOR	ECOSYSTEM DISRUPTION
Malaria	Plasmodium spp. (protozoa)	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)	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	Dengue Virus Flavivirus	Iquitos, Peru	Humans, monkeys	Aedes aegypti ('urbanized' mosquito)	Human encroachment Mosquito breeds in stagnant water found in manmade containers
Cholera	Vibrio cholerae (bacteria)	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	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	Yellow Fever Virus Flavivirus	Peru	Humans, monkeys	Aedes aegypti ('yellow fever' mosquito)	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
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	Brackish warm water	None known	Runoff of land-based pollution?? (agricultural wastes, sewage, pesticides, industrial effluents, etc.)
West Nile Fever (Encephalitis)	West Nile Virus Arbovirus	Africa to New York to contiguous United States	Birds (crows, blue jays, raptors, etc.)	Mosquito	Air travel with stowaway virus-carrying insects??

** Location described in television show (not representative of worldwide geographic distribution)

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.