364 M^LALGHLIN. 



raised to 32.5 per cent, while tlie usual incidence in cliildren has 

 been 33 per cent. For this reason, the upward curve upon tlie charts 

 of meningitis, enteritis, and dysentery of the last quarter does not show 

 so sharp a rise coincident with the cholera outbreak. 



There is no foundation for the theory that cholera vibrios live outside 

 of the human body for months during the inter-epidemic periods. There " 

 is scientific evidence to show that this is improbable if not impossible. 

 It has been demonstrated also that the duration of cholera vibrios in 

 the human intestine is limited, both in trae cases of cholera and in 

 "vibrio carriers." In the majority of cases the duration is less than 

 ten days. 



The periods of quiescence between epidemics vary from sevei'al months 

 to years. One hears constantly in the Philippines the statement that 

 cholera always recurs in the same places, the inference being that the 

 infection lies dormant for months or years and suddenly, under favorable 

 conditions, breaks out in epidemic form. There is no scientific evidence ■ 

 to support such an inference. On the contrary, one outbreak of cholera 

 can be traced practically always to another source of infection in a 

 neighboring province. In the few apparent exceptions, our failure to 

 trace the source of infection is probably due to our inability to find 

 the connecting links in the chain of infection. During the past eighteen 

 months, I have never known of an outbreak of cholera which was not 

 traceable to some known source of infection, either by direct conclusive 

 evidence or by reasonable logical deduction. 



Where the periods between epidemics last for several months or for 

 years, the beginning of an outbreak in the locality is due to infection 

 "introduced from outside. In quiescent periods of less than two months 

 duration, the infection has been re-introduced or has been continuously 

 present in persons with light or with atypical symptoms of cholera. 



Three classes of unreported cases may be responsible for continuing 

 the infection of cholera from one outbreak to another, where the interval 

 between the outbreaks is short but of more than five days' duration: 



1. Cases without symptoms. ("Vibrio caniers.") 



2. Cases with slight symptoms. 



3. Cases with atypical symptoms. 



During epidemics, the importance of the "vibrio canier" in spreading 

 infection can not be overestimated, but the presence of the "vibrio 

 carrier" can not be depended upon to explain all periods of quiescence 

 of the disease, especially as such individuals are rare except during an 

 epidemic of cholera. 



It is well known that light cases of cholera occur with no symptoms 

 beyond vomiting and a slight diarrhoea, and that they may be confused 

 readily with an attack of acute gastro-enteritis. However, the atypical 

 cases of cholera in children are of far greater importance. 



