After Koch discovered the TB bacillus near the end of the 19^th Century, people finally knew that the disease could be prevented. Before this time, although the Canadian Medical Association had begun to form a sort of "germ theory" for TB, most so-called preventive measures against TB were not scientifically based and were not successful either. The simplest forms of prevention that came out of the early years following Koch’s discovery were more scientifically founded, and may have helped to decrease the spread of the disease somewhat. For example, people were reminded to cover their mouths with a tissue before sneezing, and parents were not to let small children crawl around on the ground. Many of these early "preventative measures" of TB are just common sense today.