DISINFECTION, popularly, speaking,. the process of destroying the micro-organisms which produce the class of diseases known as infectious or contagious diseases. These dis eases are communicated in various ways. Lep rosy, anthrax, rabies, the plague and diseases of the genital system are communicated by the direct contact of a healthy body with a dis eased body. The dry germs of measles, chick enpox, smallpox, scarlet fever and tuberculosis float freely in the atmosphere and being in haled may find lodgment. The tiny drops of mucous emitted in coughing, sneezing, talking, laughing and singing may convey the germs of influenza, diphtheria, whooping-cough, phthisis, tuberculosis, spotted fever and glanders. The disease germs of typhoid fever, dysentery and cholera are abundant in the urine and excreta of the patients, and may be spread by spattering when the vessels are cleansed, or they may find their way into wells and reservoirs through the wash of rain. The germs of anthrax, lockjaw and malignant edema settle upon the soil and are likely to make their way thence into open wounds. Malaria, yellow and spotted fevers, the plague, sleeping sickness and some others are transferred from a sick person to a well person by mosquitoes, fleas, gnats or other bit ing insects. Flies carry on their legs, and un destroyed in their intestines, the germs of many diseases and distribute them everywhere, particularly on human foods which are also fly foods: and most kinds of food are excep tionally good breeding ground in which many disease germs multiply with great rapidity. It is to be remembered also that infection is not likely to cease with the primary contact. A germ originally in the soil may be carried for a long distance in a bit of mud on a shoe and thence transferred to a shoe-brush, or to some caressing animal, and so start on a long jour ney in which it may menace any person who is in a state of health susceptible to attack by that particular disease. It is to be understood, of
course, that the vast majority of persons, al though equally exposed, are not infected and diseases do not develop in them. The office of disinfection is to protect the susceptible ones.
Practically, then, disinfection is the freeing of articles or substances from the adhering or inhering disease germs, either by removing the germs bodily, or by destroying them where they are. The first method employs mechanical devices, such as filters for drinking-waters, the use of vacuum cleaners, scrubbing wall-paper with stale bread and woodwork with soap and hot water, etc. In the same category would be the coating over of germs with whitewash, cal cimine, paint or varnish. The destruction of germs where they are is a wider field and calls for intimate knowledge of the germ to be de stroyed and of the particular substances which will be fatal to it and the conditions under which such remedies must be applied to be ef fective. For a general description of these agents and the methods of using them, see the article DISINFECTANTS.
The United States government has pub lished several very complete and valuable pamphlets on disinfection and the proper use of disinfectants: Farmers' Bulletin 345 (1913); Hygienic Laboratory Bulletin 82 (1912) Public Health Service Bulletin 42 (1911) ; and Public Health Service Reprint No.287 (1915). In this encyclopedia individual prophylaxis against contagion is described under each in fectious disease and can best be consulted in its proper place. See AwriszPries; BACTERIA; DIS