INFECTION (Lat. infectio, a dyeing. from inlicere, to dye, mix, from in. in ± lam cc, to make). The condition produced by the entrance into and multiplication within the body of patho genie micro-organisms. whether bacteria or pro tozoa. Every infectious disease has its infectious clement. Phis element may be propagated by contagion from particles carried by the air, as whene the virus of the disease clings to scales of epidermis in scarlet fever or smallpox; it May be propagated by contagion from fa••1 mat ter, in which the virus is discharged, as in typhoid fever or cholera. Whether micro-organ isms can be transmitted after elimination in the breath is yet uncertain. Probably they can be detached from mucous surfaces by the currents of the breath, freed by expulsive coughing.. The mode of elimination of the virus Inuit the body decides whether the disease he contagions or not. The significance of the question of the reproduc tion of infectious miero-organisms outside of the holly is great. Drinking-water may lie
minted with typhoid-fever germs; milk may be contaminated with pus germs. The virus of some diseases may be carried by the air, as in the case of pulverized sputa of tuber cular patients. Probably the virus of yel low fever may he conveyed through the atmos phere. Actual contact with the agents of infec tion, however, constitutes the chief means of in fection. Predisposition plays a secondary part as it factor in such causation. _Ra•e intlinmees sus ceptibility to disease. The size of the dosage if bacteria is important, a large injection pro ducing disease where immunity to small doses exist s.
Auto-infection occurs where. in a parturient woman, for example. septicaania occurs as a re sult of infection of the uterus with pathogenic geniis which hare gained entrance into the va gina. Nee IMNICNITY : CON I' ‘(.ION.