Pathogens
Fecal Borne
With a high concentration of human population comes a high concentration of human waste, especially fecal waste. One consequence of urbanization is that bacteria and other pathogens present in sewage can leak out into the groundwater, contaminating both the water humans depend on and the springs that depend on the groundwater [17]. The species surrounding these sources of water can be negatively affected, leading to a rippling loss of biodiversity across an ecosystem if the pathogen is particularly harmful.
Urban to Wildlife Transmission
The effects of dense human populations on human disease transmission are well known, but little research has been done on the role of urbanization and transmission of wildlife disease. Though much more research is needed, evidence suggests that urbanization can increase disease transmission rates to wildlife [18]. Rabies is a prime example of disease spreading rapidly between urbanized areas and the surrounding wildlife with the most common transmission coming from the domesticated dog, a fixture in American urbanization. Rabies is made even more potent by its high mortality rate and the fact that all mammals are susceptible to the virus, though with the advent of mandatory canine vaccinations there has been a sharp decrease in rabies cases around the United States [20].
Vicious Cycle
Lowered biodiversity caused by various factors can also exacerbate the pathogen problem, creating a vicious cycle of lack of biodiversity leading to increased pathogens causing further decreases in biodiversity. Lyme disease, for instance, is more prevalent in the northeastern United States in part due to the loss of mammalian biodiversity and the resulting increase in the population of white-footed mouse (Peromyscus leucopus) [18]. The increased infection rates of these mice spread to ticks and other mammals, causing further harm to the ecosystem. West Nile Virus is another well-known disease potentially encouraged by urbanization [20].
Primary Sources
18. Bradley, Catherine A., and Sonia Altizer. "Urbanization and the Ecology of Wildlife Diseases." Trends in Ecology & Evolution 22.2 (2007): 95-102. Print.
Secondary Sources
17. "The Effects of Urbanization on Water Quality:Waterborne Pathogens." USGS Water Science School. USGS, n.d. Web. 25 Feb. 2014. <http://water.usgs.gov/edu/urbanpath.html>.
19. "Essential Rabies Maps." World Health Organization. WHO, 2007. Web. 03 Mar. 2014. <http://www.who.int/rabies/rabies_maps/en/>.
20. "Rabies." Media Center. World Health Organization, July 2013. Web. 24 Feb. 2014. <http://www.who.int/mediacentre>.
"Legionella and Water-borne Pathogens." Environmental Risks in Healthcare. N.p., n.d. Web. 03 Mar. 2014. <http://www.risknomicsllc.com/insurance-risk-legionella-and-water-borne-pathogens-0>.
With a high concentration of human population comes a high concentration of human waste, especially fecal waste. One consequence of urbanization is that bacteria and other pathogens present in sewage can leak out into the groundwater, contaminating both the water humans depend on and the springs that depend on the groundwater [17]. The species surrounding these sources of water can be negatively affected, leading to a rippling loss of biodiversity across an ecosystem if the pathogen is particularly harmful.
Urban to Wildlife Transmission
The effects of dense human populations on human disease transmission are well known, but little research has been done on the role of urbanization and transmission of wildlife disease. Though much more research is needed, evidence suggests that urbanization can increase disease transmission rates to wildlife [18]. Rabies is a prime example of disease spreading rapidly between urbanized areas and the surrounding wildlife with the most common transmission coming from the domesticated dog, a fixture in American urbanization. Rabies is made even more potent by its high mortality rate and the fact that all mammals are susceptible to the virus, though with the advent of mandatory canine vaccinations there has been a sharp decrease in rabies cases around the United States [20].
Vicious Cycle
Lowered biodiversity caused by various factors can also exacerbate the pathogen problem, creating a vicious cycle of lack of biodiversity leading to increased pathogens causing further decreases in biodiversity. Lyme disease, for instance, is more prevalent in the northeastern United States in part due to the loss of mammalian biodiversity and the resulting increase in the population of white-footed mouse (Peromyscus leucopus) [18]. The increased infection rates of these mice spread to ticks and other mammals, causing further harm to the ecosystem. West Nile Virus is another well-known disease potentially encouraged by urbanization [20].
Primary Sources
18. Bradley, Catherine A., and Sonia Altizer. "Urbanization and the Ecology of Wildlife Diseases." Trends in Ecology & Evolution 22.2 (2007): 95-102. Print.
Secondary Sources
17. "The Effects of Urbanization on Water Quality:Waterborne Pathogens." USGS Water Science School. USGS, n.d. Web. 25 Feb. 2014. <http://water.usgs.gov/edu/urbanpath.html>.
19. "Essential Rabies Maps." World Health Organization. WHO, 2007. Web. 03 Mar. 2014. <http://www.who.int/rabies/rabies_maps/en/>.
20. "Rabies." Media Center. World Health Organization, July 2013. Web. 24 Feb. 2014. <http://www.who.int/mediacentre>.
"Legionella and Water-borne Pathogens." Environmental Risks in Healthcare. N.p., n.d. Web. 03 Mar. 2014. <http://www.risknomicsllc.com/insurance-risk-legionella-and-water-borne-pathogens-0>.