United States raw milk debate prior to symptom onset." Milk collected or stored in unsanitary conditions may harbor a host of disease-causing organisms (pathogens), such as "tuberculosis" (Mycobacterium bovis), the bacteria "Campylobacter" (Campylobacteriosis), "Escherichia" E. coli O157:H7), "Listeria" (Listeriosis), "Salmonella" (Salmonellosis), "Yersinia" (Yersinia enterocolitica), and "Brucella" (Brucellosis). Pasteurization consistently removes all of these pathogens, though they can be reintroduced if the product is handled carelessly. Thus dairy farms that pasteurize their milk can have unsanitary facilities without the attendant outbreaks of disease that would occur if a raw milk dairy kept its herds in similar unsanitary conditions. People with weakened immune systems, such as elderly,
Brucellosis alces"), and marine mammals (see section on aquatic wildlife above). While some regions use vaccines to prevent the spread of brucellosis between infected and uninfected wildlife populations, no suitable brucellosis vaccine for terrestrial wildlife has been developed. This gap in medicinal knowledge creates more pressure for management practices that reduce spread of the disease. Wild bison and elk in the greater Yellowstone area are the last remaining reservoir of "B. abortus" in the US. The recent transmission of brucellosis from elk back to cattle in Idaho and Wyoming illustrates how the area, as the last remaining reservoir in the United