Effects of aflatoxin on the development of acquired immunity to swine erysipelas.

: The effect of aflatoxin consumption on the development of acquired immunity to swine erysipelas was studied. Twenty-four pigs were divided into 4 groups (6 pigs/group). Two groups were fed a normal diet and 2 groups were fed the same diet but containing aflatoxin. One group from each diet treatment was given a single injection of an erysipelas bacterin, and 21 days later all pigs were given a challenge inoculum of virulent Erysipelothrix rhusiopathiae organisms. On the basis of the response to the challenge inoculation, pigs were classified as immune, partially immune (PI), or susceptible. Three of the vaccinated pigs fed the normal diet were immune, 2 were PI, and 1 was susceptible, whereas none of the vaccinated pigs given the aflatoxin diet were immune, only 1 was PI, and the remainder were susceptible. Two of the nonvaccinated pigs fed the normal diet were PI and 4 were susceptible; all of the nonvaccinated pigs fed the aflatoxin diet were susceptible. It was concluded that aflatoxin consumption interfered with the development of acquired immunity and apparently increased the severity of the E rhusiopathiae infection in unvaccinated pigs.