United States raw milk debate systematic review of the food safety of unpasteurized milk concluded that science-based data to substantiate claims of health benefits "are lacking or do not exist" and the risks associated with disease outbreaks as a result of raw milk consumption are "considerably higher". Pasteurization was first used in the United States in the 1890s after the discovery of germ theory to control the hazards of highly contagious bacterial diseases, including bovine tuberculosis and brucellosis, that could be easily transmitted to humans through the drinking of raw milk. Initially after the scientific discovery of bacteria, no product testing was available to determine
Swine brucellosis nickel transport, "nikA", is activated by metal ion deficiency and is expressed once in the phagosome. Nickel is essential for many enzymatic reactions, including ureolysis to produce ammonia which in turn may neutralize acidic pH. Since "B. suis" is unable to grow in a strongly acidic medium, it could be protected from acidification by the ammonia. Summary: The most frequent clinical sign following "B. suis" infection is abortion in pregnant females, reduced milk production, and infertility. Cattle can also be transiently infected when they share pasture or facilities with infected pigs, and "B. suis" can be transmitted by cow’s milk.