_3. Pollution of milk utensils._ The most frequent method of infection of cans, pails, etc., is in cleaning them with water that may be polluted with disease organisms. Often wells may be contaminated with diseased matter of intestinal origin, as in typhoid fever, and the use of water at normal temperatures, or even in a lukewarm condition, give conditions permitting of infection. Intentional adulteration of milk with water inadvertently taken from polluted sources has caused quite a number of typhoid outbreaks.[105] Sedgwick and Chapin[106] found in the Springfield, Mass., epidemic of typhoid that the milk cans were placed in a well to cool the milk, and it was subsequently shown that the well was polluted with typhoid fecal matter. _4. Pollution of udder_ of animal _by wading in infected water_, or by washing same with contaminated water. This method of infection would only be likely to occur in case of typhoid. An outbreak at the University of Virginia in 1893[107] was ascribed to the latter cause. _5. Pollution of creamery by-products, skim-milk, etc._ Where the milk supply of one patron becomes infected with pathogenic bacteria, it is possible that disease may be disseminated through the medium of the creamery, the infective agent remaining in the skim milk after separation and so polluting the mixed supply. This condition is more likely to prevail with typhoid because of the greater tolerance of this organism for acids such as would be found in raw milk. The outbreaks at Brandon,[108] England, in 1893, Castle Island,[109] Ireland, and Marlboro,[110] Mass., in 1894, were traced to such an origin. While most outbreaks of disease associated with a polluted milk supply originate in the use of the milk itself, yet infected milk may serve to cause disease even when used in other ways. Several outbreaks of typhoid fever have been traced to the use of ice cream where there were strong reasons for believing that the milk used in the manufacture of the product was polluted.[111] Hankin[112] details a case of an Indian confection made largely from milk that caused a typhoid outbreak in a British regiment.