AFRICAN TICK FEVER 443 



isms reappear in the blood, the relapse being, however, of 

 shorter duration and less severe than the first attack. This is 

 repeated till the immunity lasts long enough to allow all the 

 organisms to be killed. The production of anti-substances 

 during the febrile attack is an established fact, and the experi- 

 mental results above detailed show that the disease as met with 

 in the human subject will probably be eminently amenable to 

 serum therapeutics. 



The fact that other like spirillar diseases may be conveyed 

 by the bites of insects makes it extremely probable that relaps- 

 ing fever may also be transmitted in this way, and a number of 

 facts point to the bed-bug as the means of transmission. The 

 presence of the spirilla within the bodies of bugs has been 

 demonstrated, and it has also been shown that they may be 

 present for a considerable time after the insects have sucked the 

 blood, according to Karlinski for forty days. Tictin, by inject- 

 ing the blood removed from a number of bugs which had been 

 allowed to bite infected monkeys, produced the disease in other 

 healthy monkeys, but so far as we know the crucial experiment 

 of infecting man by means of the bites of these insects has not 

 yet been successfully carried out. 



African Tick Fever. 



The disease long known by this name as prevalent in Africa 

 has also been shown to be caused by a spirillum or spirochaete. 

 Organisms of this nature had been seen in the blood of patients 

 in Uganda by Greig and Nabarro in 1903, and Milne and Ross 

 in the end of 1904 recorded a series of observations which led 

 them to the conclusion that tick fever was due to a spirochsete. 

 It is, however, chiefly owing to the work of Button and Todd in 

 the Congo Free State, on the one hand, and of Koch in German 

 East Africa, on the other, that our knowledge of this disease has 

 been thoroughly established. The former gave a full account of 

 the organism, and by means of experiments showed that the 

 disease could be transferred by means of ticks to healthy 

 animals. The latter published interesting observations on the 

 infection of the ticks and the transmission of the organisms to 

 the young, and also important facts with regard to the extent to 

 which ticks were infected in certain districts. 



The following are the chief facts regarding this fever. 

 Clinically the fever closely resembles relapsing fever, but the 

 periods of fever are somewhat shorter, rarely lasting for more 

 than two or three days. It is rarely attended with a fatal result 



