As man learns how to keep himself more clean and sanitary practices spread through the world, some of our worst diseases are gradually eliminated. One of these is typhoid fever. Just 60 years ago, thousands upon thousands of people were dying from it every year. Now deaths from typhoid average only a fraction of what they were, and are now confined mainly to the more backward regions.

Typhoid fever is caused by a bacillus called Salmonella typhosa. It lives in the products of excretion. After it leaves the body, the bacilli can continue to exist, but they do not multiply.