July 5, 1912] 



SCIENCE 



DIPHTHERIA 



As regards diphtheria, investigations 

 have shown that the healthy carriers are 

 never found in regions free from the dis- 

 ease. They are met with only in places 

 where the disease prevails; the home, hos- 

 pital, asylum, school and, naturally, the 

 large city furnish examples, though in ex- 

 tremely variable number. Intimate asso- 

 ciation with the patient, either before or 

 during sickness, as is likely to occur in the 

 home, yields the largest percentage of such 

 carriers. This is especially true where 

 preventive measures, such as isolation and 

 disinfection, are not enforced at the outset. 

 Under such conditions it has been found 

 that fully one third of the exposed become 

 carriers for a greater or less length of time. 

 Where proper measures are instituted 

 early, the number is necessarily greatly 

 reduced. Systematic examinations made 

 in the large cities have, time and again, 

 demonstrated the presence of healthy car- 

 riers in from 2 to 4 per cent, or more of 

 the persons tested. 



The persistence of the organism in the 

 healthy carrier is usually, and fortunately, 

 of short duration, though exceptionally it 

 may continue to be present for months. 

 Such carriers are unquestionably a source 

 of danger to others and serve to explain 

 outbreaks of the disease where contact with 

 a sick person is positively excluded. The 

 fact that the blood of a majority of the 

 healthy carriers possesses antitoxic proper- 

 ties indicates clearly that they have passed 

 through a previous, though unrecognized, 

 mild infection and consequently that they 

 really belong to the type of chronic car- 

 riers. A small number of the healthy car- 

 riers may eventually themselves develop 

 the disease, while others, for some unknown 

 reason, escape infection. 



The convalescent and chronic carriers are 



properly looked upon as being dangerous 

 to the community. It is a well-recognized 

 fact that the diphtheria bacillus persists in 

 the throat and nose, for a variable period 

 of time, after the disappearance of all 

 clinical sjonptoms of the disease. It may 

 remain present for a few days, weeks or 

 months. Fortunately, the vast majority 

 rid themselves of the invading organism in 

 a relatively short time, but as long as they 

 harbor the organism they are in a position 

 to infect others. Isolation, under such con- 

 ditions, is just as necessary as in the acute 

 stage of the infection. The really chronic 

 carrier, the one who harbors the germs for 

 months, if not years, presents the most dif- 

 ficult problem. 



TYPHOID FEVER 



The studies on typhoid fever during the 

 past few years have been especially fruitful 

 in enlarging our knowledge of human car- 

 riers and have served to concentrate at- 

 tention to the important part played by 

 these in the propagation of the disease. 

 The accepted cause, the typhoid bacillus, is 

 known to be present not only in the intes- 

 tines, but also in the internal organs and in 

 the blood. Because of the latter occur- 

 rence the majority of typhoid patients, 

 after about the twelfth day of the disease, 

 eliminate the typhoid bacillus in the urine, 

 at times in enormous numbers, and such 

 elimination may continue for weeks after 

 complete recovery has taken place. Excep- 

 tionally, the typhoid bacillus may persist 

 in the urine or discharges for months, and 

 years, if not through the remainder of life. 



The problem of the healthy carrier is 

 one of special import. Here, as before, we 

 have those who have undoubtedly passed 

 through a previous mild and unrecognized 

 attack of the disease and hence are of the 

 type of true chronic carriers ; as such, they 

 are to be looked upon as particularly dan- 



