It's also worth noting the correlation between the reduction in urban horses and the reduction in human cases of tuberculosis. TB killed up to 25% of the urban

It's also worth noting the correlation between the reduction in urban horses and the reduction in human cases of tuberculosis. TB killed up to 25% of the urban poor in the late 19th century; infective vectors included infected milk (from bovine infection reservoirs), poor living conditions that enforced proximity to TB sufferers, and proximity to TB-infected livestock -- of which horses would have been the main reservoir in urban areas.