A type of bacteria found in the soil (B.tetanus), in milk (B.acidophilus or lactic acid bacillus) and in the intestines of men and animals (B.Coli).They are rod-shaped,microscopic vegetable or organisms.
Some are disease-producing , e.g B.tetanus, others are benevolent parasites, e.g,B.acidophilus.The colon bacilli are harmless as long as they are confined to the large intestine, but will become virulent if by carelessness in hygiene they are transferred to another part of the body or to a different host.
The same is true of virulent bacteria such as the diphtheria germ, to which a person may become immune when harbored in his nose for a long time.But let that person pick his nose with his fingers, then, without washing his hand with plenty of soap and water, poke his ear with the same finger,-thus transplanting the germ from his nose to his ears-and a serious ear infection will probably follow.
Also if this person sneezes without covering his nose, and the germ which is harmless to him is inhaled by a member of his family or a stranger, those persons will develop a diphtheretic infection or a streptococcus infection depending on the kind of germ coughed or sneezed.
The only way to prevent these infections in yourself and others is to wash the rectum with soap and water after each bowel movement,carefully cleanse the nose and cover coughs and sneezes, and thoroughly wash your hands after contact with discharges from any part of the body