112 The Philippine Journal of Science 1920 
It was during 1911 and 1912 that the first diphtheria carriers 
were detected, twenty-four having been found. Examination 
was done, as customary, by the laboratory of the Bureau of 
Science, for the Bureau of Health. As the health officials looked 
upon these carriers as being more dangerous in the spread of in- 
fection than the frank cases of diphtheria, the former were all 
isolated and so kept until the bacilli disappeared as shown by 
two successive negative findings on separate days. In conse- 
quence of this discovery, and in order to combat the disease, 
specific instructions were issued to medical officers, one im- 
portant feature of which was that relating to the detection 
and control of carriers. Worthy of mention is the fact that 
the longest time that bacilli have remained in the throats of 
diphtheria patients in San Lazaro Hospital was twenty-eight 
days from the time of disappearance of the symptoms. The 
longest time for a contact carrier to harbor the bacilli after 
admittance to the hospital was eighteen days. 
From that time on, carriers have been continually detected 
in connection with the annual outbreaks of diphtheria. 
The 1915 outbreak was attended by a high mortality and the 
occurrence of a large number of carriers from whom a high 
proportion, 35.71 per cent, of virulent cultures was isolated by 
the Bureau of Science. One important thing observed in this 
outbreak was the development of symptoms of diphtheria (fever, 
pharyngitis, etc.) in twenty-two, or 3.65 per cent, of the carriers 
after admission to the hospital. Prompt administration of 
serum prevented the further development of the disease and 
probably the death of the patients. The Health Service strongly 
suspected that the sporadic but constant appearance of cases 
might possibly be due to perpetuation of a certain strain through 
the agency of bacillus carriers. 
In 1915 a survey of diphtheria carriers among exposed 
persons in households, schools, and other institutions revealed 
the existence of 9.64 per cent of diphtheria carriers, which is 
excessive as compared with 3 per cent reported for some parts 
of the United States. This signifies: (1) perpetuation of a 
certain strain in Manila by uncontrolled carriers; or (2) an 
indication of an actual or closely threatening epidemic. The 
development of symptoms in some carriers was explained by the 
possibility of increase in virulence of harmless bacilli in carriers. 
In 1916 the diphtheria outbreak showed a marked improve- 
