SivVulk
02-15-2012, 05:17 PM
For years, scientists have been forecasting that loss of diversity would increase the prevalence of disease. Now, they are starting to gather evidence. What they are finding is that high diversity among small mammals appears to regulate the population of animals that host deadly diseases through competition or predation.
Soon after the West Nile virus began killing off crows in New York City, the first humans succumbed to the disease. While many species can play host to the disease, birds are one of the most deadly carriers — particularly sparrows, finches, robins, bluejays and grackles. These birds thrive in heavily fragmented and degraded habitats. They are also common around humans. Yet while humans can succumb to the disease, they are not carriers.
Scientists believe that a larger pool of food for mosquitoes leads to mosquitoes feeding off hosts such as humans, alligators and horses that do not carry the pathogen. The more diverse the supply of food for the mosquitoes to feed on, the less likely they are to feed from an infected source.
Lyme disease is another deadly disease that spreads from animals to humans. While the black-legged tick that carries Lyme disease feeds on a variety of vertebrate species, the white-footed mouse is the most deadly carrier. This mouse infects over 90% of all ticks that feed on it. While almost all gray squirrels carry the bacterium that cause Lyme disease, only 15% of ticks that feed on gray squirrels will become infected. Consequently, Lyme disease is much more prevalent in habitats with high numbers of mice.
Tick-borne encephalitis is also caused by a deadly combination of tick bite and mouse host. However, this virus has very stringent requirements that need to be met in order for it to survive. It is spread when an infected immature tick bites a mouse at the same time as a susceptible larva is feeding. This requires the right population of yellow-necked mice. When the population is too high, the probability of an immature tick and larva tick feeding on the same host at the same time is too low. When the population is too low, there are not enough ticks produced to carry the virus.
http://www.environmentalgraffiti.com/news-complex-connection-between-animals-and-human-disease
Just as the proposed dichotomy of two separate spheres of the domestic sphere of women and public sphere of men has been debunked so to is the distinct separation between the natural world and the "human" world
Soon after the West Nile virus began killing off crows in New York City, the first humans succumbed to the disease. While many species can play host to the disease, birds are one of the most deadly carriers — particularly sparrows, finches, robins, bluejays and grackles. These birds thrive in heavily fragmented and degraded habitats. They are also common around humans. Yet while humans can succumb to the disease, they are not carriers.
Scientists believe that a larger pool of food for mosquitoes leads to mosquitoes feeding off hosts such as humans, alligators and horses that do not carry the pathogen. The more diverse the supply of food for the mosquitoes to feed on, the less likely they are to feed from an infected source.
Lyme disease is another deadly disease that spreads from animals to humans. While the black-legged tick that carries Lyme disease feeds on a variety of vertebrate species, the white-footed mouse is the most deadly carrier. This mouse infects over 90% of all ticks that feed on it. While almost all gray squirrels carry the bacterium that cause Lyme disease, only 15% of ticks that feed on gray squirrels will become infected. Consequently, Lyme disease is much more prevalent in habitats with high numbers of mice.
Tick-borne encephalitis is also caused by a deadly combination of tick bite and mouse host. However, this virus has very stringent requirements that need to be met in order for it to survive. It is spread when an infected immature tick bites a mouse at the same time as a susceptible larva is feeding. This requires the right population of yellow-necked mice. When the population is too high, the probability of an immature tick and larva tick feeding on the same host at the same time is too low. When the population is too low, there are not enough ticks produced to carry the virus.
http://www.environmentalgraffiti.com/news-complex-connection-between-animals-and-human-disease
Just as the proposed dichotomy of two separate spheres of the domestic sphere of women and public sphere of men has been debunked so to is the distinct separation between the natural world and the "human" world