﻿4 The Philippine Journal of Science ish 



A culture was isolated from a sample of human faeces, and this 

 sample was then fed to a cockroach. Twenty-nine hours after- 

 ward, a second culture was isolated from the faeces of the cock- 

 roach. Young agar cultures of the two cultures were tested by 

 intraperitoneal inoculation into 200-gram guinea pigs. In the 

 culture isolated from the cockroach, one-eighth of a loop was fatal 

 after about twenty-seven hours and one-sixteenth of a loop failed 

 to infect. In the culture isolated directly from the human faeces, 

 one-fourth of a loop was fatal in less than twenty-four hours 

 and one-eighth of a loop nonfatal. So there is no evidence of 

 I'^ss of virulence in cholera vibrios after twenty-nine hours in the 



intestine of tne cockT?^^^- 



Ordinary red ants (probably Monomonum latinode Mayr) are 

 also possible cholera carriers, since they are omnivorous feeders 

 and will penetrate to any food not carefully protected from them. 

 Some experiments were conducted on these insects, but owing 

 to the small volume of their faeces it was difficult to make a test 

 before the faeces became dry. The ants ate cholera cultures and 

 human faeces containing cholera vibrios readily, and in one group 

 of culture-fed ants cholera vibrios were recovered from the 

 crushed bodies of the insects about eight hours after feeding. 

 It is very probable that their faeces also contained living vibrios, 

 since carmine-tinted liquid faeces were discharged, but these 

 became dry before they could be tested. In a second group of 

 ants fed with human faeces, cholera vibrios were recovered from 

 the crushed bodies nearly nine hours after feeding. 



In summary, cockroaches which have fed on human cholera 

 faeces may harbor cholera vibrios in their intestines, and these 

 may appear in enormous numbers in the insects' faeces for at 

 least two days after the insects have fed, and may occur in 

 smaller numbers seventy-nine hours after ingestion. By means 

 of both faeces and vomit, cockroaches may act as carriers of chol- 

 era to human food. Cholera vibrios in cockroach faeces will sur- 

 vive on human food at least sixteen hours after discharge from 

 the insect, and cholera vibrios in human faeces will survive, in 

 competition with numerous other bacteria, on food at least four 

 days. There is no loss of virulence for guinea pigs in cholera 

 vibrios after twenty-nine hours in the intestine of the cockroach. 

 Cholera vibrios may be found in the bodies of ants at least eight 

 hours after they have ingested cholera cultures or human faeces 

 from cholera patients. 



