294 THE CARRIAGE OF VARIOUS MICRO-ORGANISMS 



in the fly's gut. Further experiments recorded by Howard and 

 Clarke (1912) demonstrated that M. domestica retained the virus 

 either in or on their bodies for at least twenty-four and forty-eight 

 hours respectively. They also showed that the virus may remain 

 in a viable condition in the alimentary tract of the fly for at least 

 six hours. The possibility of flies obtaining infection from the 

 infected discharges from the nose and throat or intestine is 

 indicated. Further reference to the transmission of this disease 

 is made under Stomoxys calcitrans. 



Trypanosomes. 

 On account of its non-blood-sucking habits, feAv experiments 

 have been carried out with a view to demonstrating the possibility 

 of M. domestica caiTying Trypanosomes. Reference has already 

 been made to investigations on the relation of flies to the allied 

 organisms causing Tropical Sore. Experiments are recorded^ in 

 which M. domestica was fed for 3 — 4 minutes on blood ft'om a 

 guinea-pig infected with Trypanosoma hippicum; after an interval 

 of about 30 seconds the flies were placed over the scratched skins 

 of mules for about five minutes and it was demonstrated that this 

 trypanosome may be transmitted by the flies-. 



Surra. 

 Mitzraain (1913) states that in experiments w^ith Stomoxys 

 calcitrans and live stock, Surra organisms have been demonstrated 

 in the mouth parts and stomachs of house-flies. 



Danysz virus. 

 An interesting experiment on the carriage of Danysz rat virus 

 was carried out by Graham-Smith (1910). Flies artificially infected 

 with the virus by feeding were allowed to settle and feed on a 

 piece of bread soaked in milk. After one hour the bread was 

 given to a mouse. A mouse which had fed upon bread given to 

 flies forty-eight hours after infection died in two days and the 

 virus was isolated from the spleen; another mouse fed on bread 

 given to the flies four days after infection died in tw^o days. In 



1 Report Dept. Sanit. Isthmian Canal Comm., Dec. 1911, pp. 42, 43. 



- The possibility of M. domestica acting as a vector of T. hippicum is con- 

 vincingly treated by Darling (191.3) who suggests that more attention be paid to 

 the possible relation of M. domestica to trypanosome diseases. 



