51 



Leishman and Hindle consider that the infection is not 

 transmitted by this channel, but that the infective excre- 

 ment from the Malpighian glands passing out per rectum is 

 washed into the puncture made by the insect by means of 

 the coxal secretion which is deposited during the latter 

 stages of feeding. 



THE TRANSMISSION OF THE RELAPSING FEVERS OF 

 EUROPE, AMERICA, AND INDIA. 



Whether the spirochastse which are responsible for 

 relapsing fever in various parts of the world represent 

 distinct species (Novy and Knapp (1906), Uhlenhuth and 

 Haendel (1907) ), or merely varieties, does not seem to me 

 proven in view of the observations of Darling (1909) and 

 Manteuf el (1908). Anyhow, they are very similar and all can 

 be transmitted by the tick Orniihodoros moubata (Manteufel 

 (1908) and Neumann (1909) ). It is, however, clear that this 

 tick was not the transmitting agent in Ireland and England, 

 where relapsing fever was common 50 years ago, nor is it so 

 in .Russia, America, or India at the present time. 



The epidemiology of the disease in these countries is not 

 yet clear. Spirochastse are such obligatory parasites that 

 the agency of an insect transmitter seems almost necessary. 

 The only certain way of producing the disease is by inocu- 

 lating a 'minute quantity of the blood of a patient during the 

 febrile stage. Spirochtetas have been found in the urine, 

 but no one has succeeded in producing infection by this 

 means. It must also be remembered that they can find their 

 way through the unbroken skin. 



The distribution of relapsing fever among the population 

 is consistent with the view that insects are necessary, for, 

 like typhus, this disease in Europe is almost confined to the 

 poorest and dirtiest members of the community. It has 

 been frequently suggested that bugs might disseminate the 

 disease ; Tictin (1897) and Karlinski (1902) found that the 

 stomach contents of the bed bug remained infective for two 

 or three days after feeding on the blood of a patient ; and 

 Kladnitzky (1908) observed appearances strongly suggestive 

 of multiplication of the spirochyetse in the stomach of the bug. 

 With one exception, however, all the numerous attempts to 

 transmit the disease by the bed bug have been unsuccessful. 

 Experiments have also been made with fleas by Sergent and 

 Foley (1908) and others. The results were negative ; a further 

 reason for doubting the importance of either of these insects 

 is that the disease is not more prevalent at the time of year 

 when these insects abound, but rather the contrary, for in 

 Europe, although the disease occurred in epidemic form 

 throughout the year, the greatest prevalence was usually 

 during winter and spring. 



