I've included here a few studies showing how eating a raw diet, without incidence from parasitic disease is possible. The studies show 1. that wild animals are generally unaffected by parasites, 2. that wild animals have increased parasitism with increased pollution, 3. that wild animals moved into captivity and fed a standard feed (cooked foods, etc.) develop increased parasitism, and 4. a link to an international study done on heat created byproducts (approximately 50 byproducts listed), and 5. studies on bacteria, mad cow, etc.
Essentially, pollution and heat created byproducts (possibly other factors too) decrease animal resistance to microbes (including parasites), by reducing glutathione levels (and likely other antimicrobial factors as well). Which is why raw dieters are generally unaffected. Basically pollution=heat created byproducts, increased pollution increased parasitism.
http://www.ncbi.nlm.nih.gov/pubmed/2069073"There is also evidence that endoparasitic protozoons, such as myxozoons, microsporans and haematozoons, all of which are capable of proliferating in their hosts, increase substantially in prevalence and intensity when interacting with pollutants."
http://www.ncbi.nlm.nih.gov/pubmed/1805675"Pollutants might promote increased parasitism by impairing the host's immune response or favouring survival and reproduction of intermediate hosts."
http://www.ncbi.nlm.nih.gov/pubmed/10456421"Parasites, causing little apparent damage in feral (wild) fish populations, may become causative agents of diseases of great importance in farmed fish, leading to pathological changes, decrease of fitness or reduction of the market value of fish."
http://www.fhi.no/eway/default.aspx?pid=240&trg=Content_6870&Main_6664=6898:0:25,8254:1:0:0:::0:0&MainContent_6898=6870:0:25,8279:1:0:0:::0:0&List_6871=6874:0:25,8279:1:0:0:::0:0&Content_6870=6866:97806::1:6875:11:::0:0"Modern science has showed that heating of meat and other protein rich foods can generate various kinds of potentially hazardous compounds, some of which are genotoxic and carcinogenic. The focus of the HEATOX project was to estimate health risks recently discovered associated with hazardous compounds in heat treated carbohydrate-rich foods where substantial amounts of acrylamide and similar compounds can be formed."
http://www.eatwild.com/foodsafety.html"Grass-fed cows are not mad cows
Eating grass-fed beef may lower your risk of E. coli infection"
