Intraspecies differences of resistance against leprosy in nine-banded armadillos

Infection of nine-banded armadillos with decreasing doses of armadillo-passaged leprosy bacilli show that most individuals of this species are susceptible and only about 20 percent are resistant regardless of the size of the infecting bacterial dose. It is pointed out that the intraspecies distribution of resistance to leprosy in human beings and in nine-banded armadillos differs because most individuals of the former species are resistant. Attention is drawn to the possibility that the results of anti-leprosy vaccination in armadillos might not apply to vaccination of human beings because the differences in distribution of resistant individuals might also reflect different mechanisms of susceptibility in the two species.