8o Infection 



latent foci of disease, when they succeed in penetrating into the 

 blood and escaping the destructive effects of the defensive mechan- 

 ism, if transported to distant parts may initiate new morbid proc- 

 esses formerly known as idiopathic, but in the light of present 

 knowledge better known as cryptogenic infections. Such are 

 exemplified by primary endocarditis, pericarditis, pleuritis, arthritis, 

 meningitis, etc. 



HUMAN CARRIERS OF INFECTION 



In some cases pathogenic micro-organisms, /ailing upon the 

 surfaces of the body, find the conditions suitable for life and multi- 

 phcation, though unsuited for invasion, and remain indefinitely, 

 though apparently doing no harm. More frequently, the recovery 

 from an infectious disease is attended by a form of immunity that 

 determines that the infectious agent can no longer do the patient harm, 

 though it is not necessarily extinguished from all parts of the body. 



In either case the individual becomes a "carrier" of infectious 

 agents that may be transmitted to others. Thus, the examination 

 of the nasal secretions of large numbers of persons show that a few 

 harbor meningococci though they may never have had meningitis, ■ 

 but that more harbor meningococci who have had meningitis. 

 But in either case, the carrier may transfer the meningococci to 

 others, through the indiscriminate use of handkerchiefs, wash-rags, 

 towels, etc., who may readily become infected with the disease, 



A nurse that has attended a child through diphtheria or a doctor 

 that has visited a case of diphtheria, or other healthy children in a 

 household in which there has been diphtheria, may have a few 

 diphtheria bacilli in the nasal, tonsillar or pharyngeal mucosae, that 

 may not be able to induce disease because the individuals are not 

 receptive, and which may not die out for a long time. The child 

 recovered from diphtheria, though entirely well, frequently carries 

 large numbers of diphtheria bacilli upon the formerly diseased 

 membrane, for weeks. Under such circumstances, the healthy persons 

 who have not had the disease and the well child that has recovered 

 from it are alike "carriers" of diphtheria andmay spread the micro-or- 

 ganisms to new and susceptible persons who quickly become diseased. 



Though the patients seem entirely to have recovered from gonor- 

 rhea, gonococci frequently remain alive in the previously inflamed 

 passages, so that such persons are "carriers," and though seemingly 

 entirely free of disease readily transmit it to others. 



The t)^hoid bacilli escaping from the blood of the patient in 

 the bile and urine, remain alive in the urinary bladder for many 

 weeks and in the gall-bladder for many months after complete 

 recovery. As they grow readily in both locations, the numbers that 

 are discharged with each emptying of the receptacles in which they 

 are multiplying may be enormous and makes the individual a 

 "carrier" until they are no longer present. 



