Here is one section of my paper. It's just on the diseases that dairy cows transmit to wildlife. No references yet, sorry...
There is a long history of human activity bringing disease to wildlife, starting with the Pleistocene extinction of large animals. The issue of disease transmission between domestic and wild animals has traditionally emphasized the role of wildlife as a reservoir for livestock diseases. In particular, wild ruminants have been blamed for the spread of diseases through their excreta. Pastoral systems are especially vulnerable, since grazing areas and water resources are shared.
There is strong evidence of disease transmission from livestock to wildlife, though. Such directional transmission becomes more problematic as wildlife habitat is further and further decreased and fragmented, concentrating wildlife populations. The resulting crowding increases chances for disease transmission and stresses their immune systems, leaving them more vulnerable to disease.
Listeria monocytogenes causes listeriosis in both non-human (deer, moose, raccoon, otter) and human animals, causing sepsis in young animals and abortions in pregnant animals. Ruminant animals often contract encephalitis; humans contract meningitis. The bacterium propagates in bovine gi tracts and persists in slurry, manure, and bedding for two years.
Studies have found significant correlations between upstream dairy farms and the presence of L. monocytogenes in catchment water samples. Surrounding cropland, often fertilized with cow manure, was also implicated. However, XYZ found that the majority of contaminated water samples came from within a few kilometers downstream of a dairy farm. These farms included dairy barns, pastures, manure lagoons, and manured fields.
Intensive operations are widely known to use antibiotics prophylactically, but smaller operations in remote areas are also using them in some countries. It is generally able to acquire multiple resistance through conjugative transfer of plasmids. XYZ found the isolates were resistant to an average of 6 antibiotics. This could affect wildlife management, if a program is introduced to eradicate listeriosis and no feasible treatment can be found for wildlife.
Anthelminthic drugs and endectocides are also used in small ruminant farming, to treat or prevent parasites. Increasing nematode resistance is becoming a similar problem.
Mycobacterium avium subsp. paratuberculosis causes the much-dreaded Johne’s disease in all ruminants. It has also been found in lagomorphs, canids, mustelids, corvids, and murids. It causes chronic inflammatory bowel disease, eventually resulting in diarrhea, dehydration, cachexia, and ultimately death. Management is especially difficult because of the latency period of up to two years.
Excreted in feces and milk, M. avium is very stable in soil and water. Wild ruminants become infected by feeding on contaminated forage in rangeland shared with livestock, while other wildlife may feed on contaminated grain, feces, prey, or carcasses.
Considering the much higher prevalence of M. avium in domestic cattle, the predominant direction of transmission is from livestock to wildlife, not the other way around as often perceived by farmers. The amount of the pathogen shed by wildlife is insignificant, whereas the high density of individuals on farms as well as the sheer volume of contaminated feces make cattle-to-cattle transmission much more likely.
Mycobacterium bovis causes tuberculosis, with coughing, weakness, and loss of weight. This bacterium is shed in breath, feces, lesions, milk, saliva, and urine. It survives longest in warm, moist soil, but can tolerate dessication and a broad pH range. It has been found in badgers, deer, and wild boars, causing concern among livestock farmers. However, in East Africa, it has also spread to lions, cheetahs, and baboons. This development highlights the danger to wildlife, particularly endangered wildlife.
Brucella abortus causes abortion primarily in ungulates like cattle, elk, and bison, but also sometimes in dogs, horses, humans, and pigs. It is shed in birthing fluids and afterbirth, and is spread through ingestion. It may have been introduced to Yellowstone bison in the early 1900’s, when dairy cattle were brought to the area to provide milk for park employees.
The potential for a zoonotic epidemic is demonstrated by the African rinderpest pandemic of the 1890’s. Rinderpest is caused by a morbillivirus. It affects cloven-hooved animals such as various antelopes, buffalo, cattle, giraffes, goats, pigs, sheep, warthogs, wildebeest, and yaks. It causes fever, depression, congestion of mucous membrances, diarrhea, progressive debiltation, and eventually death. Shed in blood, breath, eye/nose discharge, feces, milk, saliva, and urine, it is easily transmitted to other animals through contaminated soil, clothing, or equipment.
In the late 1880’s, Indian cattle shipped to feed Italian soldiers infected and killed 90% of South African cattle. Eventually, both livestock (cattle, sheep, goats) and wildlife populations (buffalo, wildebeest, giraffe) were decimated in most of sub-Saharan Africa. Somali pastoral cattle (generally dairy cattle) infected Kenyan wildlife. Sudanese cattle infected Ugandan cattle, which were brought to Tanzania by soldiers, again spreading to wildlife. Eventually, 90% of sub-Saharan cattle and millions of wild animals died of rinderpest. Meanwhile, humans, no longer able to herd or hunt, starved to death, including one-third of Ethiopians and two-thirds of Tanzanian Maasai.
In ridding the landscape of so many grazing animals, rinderpest also facilitated the changeover from grasslands to thickets. These thickets provided breeding grounds for tsetse flies, which transmitted trypanosomiasis to livestock, wildlife, and humans. Trypanosomiasis can be fatal to camels, cats, cattle, dogs, goats, horses, humans, leopards, lions, monkeys, pigs, and sheep.
A more recent concern is Bovine Spongiform Encephalopathy (BSE), one of the Transmissible Spongiform Encephalopathies (TSE) found in cervids, cats, humans, mink, and sheep. TSEs are progressive neurological diseases with no known treatment or cure. Although no studies have connected BSE with the other forms of TSEs, they have connected it with variant Creutzfeldt-Jakob Disease in humans.
It has been largely overlooked that dairy cows have figured prominently in this episode. Most of the cases in the UK (81%, as of ) were in dairy cows, as was the first case in the US. This is perhaps because the emphasis has been on the mode of transmission, which is thought to be the consumption of cow flesh, rather than milk. However, the policy banning the use of nervous system tissue only applies to cows older than 30 months. This writer notes that these are likely to include significant numbers of dairy cows, as they are slaughtered after at least a few cycles of milk production. Non-ambulatory, or “downer” cows, which are also prohibited, are also likely to be apply dairy cows, who have shifted their metabolic needs to prioritize milk production, rather than physiological maintenance.
