THE NATURE OF HUMAN TICK-FEVER 
3 
Immunity, Susceptibility, and Mortality. 
Sir John Kirk said (i), while speaking of the tick-fever on the Zambiese, 
that after recovery from tick-fever the patient had complete immunity from 
further attacks. We have been told by natives that a man can only once 
be made ill by the " Kimputu." It seems very probable that those living 
in infected localities may have relapsing fever while young, and grow up 
immune to the affection. Several Zanzibar traders have lately told us that 
the human tick " Papasi" (7) of Udjiji and Zanzibar (they assert they are 
the same as the ticks of this region) are harmless, and that their bite gives 
no disease. As already noticed, Livingstone, 111 1871, did not mention 
that the ticks — " Tapasi " — of the Arab town at Nyangwe produced any 
disease (3). Nyangwe has at present a particularly bad reputation. The 
natives living inland who are forced to come to that post always endeavour 
to avoid sleeping there. A small caravan comes monthly to Nyangwe to 
bring in produce from villages some two days' walk inland. The porters 
formerly slept at Nyangwe before returning home. As a result there was 
always some one sick with " K im putu " in their villages. It is generally 
accepted that strangers are particularly susceptible, and it seems certain 
that the majority of cases in this district occur among newcomers. All of 
our cases, save Nos. 2, 4, 7, had recently been exposed, for. probably, the 
first time to tick bites. 
The mortality from tick-fever does not seem to be very great amongst 
those who are cared for and not exposed to fatigue and hunger. Under 
adverse conditions the death rate may be high ; for example, of twenty 
carriers who contracted the disease in one caravan sent from Kasongo to 
Kabambarre ten died 
Incubation Period. 
The period intervening between the bite of the tick and the declaration 
of the disease is, from our experience, about one week. The natives usually 
put it at five days. Occasionally symptoms are said to follow within a few 
hours of the bite. In no case have we been able to personally verify the 
dates of both the bite and the commencement of the fever. 
Symptomatology. 
In the two European cases slight prodromata, mental heaviness, and lack 
of acuity were noted. In all the cases the onset of the fever has always been 
sudden, and in no instance preceded by a distinct rigor. The patient is 
prostrated, and complains chiefly of severe headache, usually frontal 
occasionally general. Boneache — in the limbs, and backache are distressing: 
the patient feels as if well beaten. There is a marked distaste for food. 
Vomiting generally occurs once or twice, but has never been continued. 
Slight diarrhoea is fairly constant, constipation may occur. The evening 
temperature during the attacks frequently reaches 1 04. 5° F. ; the highest 
temperature recorded is Io5-3deg. F. There are usually three or four attacks 
which often end in more or less profuse perspiration. As a rule each attack 
lasts for three or four days, and the intervening periods vary from five to 
nineteen days. 
