92 
Effects foUoiving Tick-hites 
seven succeeded in fastening themselves, but now (fifteen days after¬ 
wards) no fever has yet developed. This time the larvae were 
apparently those of Amhlyomma hebraeimi'^.” 
In a subsequent letter, dated 11 June, 1910, Mr Howard writes : 
“ You mention the fact of persons long resident in a locality 
becoming immune to the tick-bites. I have noticed that here. It is 
always visitors or new arrivals who are affected. 
At the present time I myself seem to be immune. Some years ago, 
soon after coming to Africa, I made a journey to Northern Zululand 
and was there bitten by larval ticks in the grass. One bite, just below 
the left knee, developed into a large sore, causing severe lameness for 
some weeks. I, however, did not, at the time, notice fever, only slight 
indisposition.” 
Dr E. Hindle, who is at present working in the Quick Laboratory, 
informs me that he and Dr Breinl suffered from the effects of the bites 
of Amhlyomma hebraeum larvae .whilst experimenting wdth these ticks 
at the Runcorn Research Laboratories, near Liverpool. The ticks were 
received in 1908 from Mr C. P. Lounsbury, Government Entomologist 
for Cape Colony; tliey were infected with Heartwater and were used 
for experiments on goats. Whilst transferring the ticks to a goat 
some of them escaped and attacked the experimenters. The ticks 
always attached themselves about the scrotum or navel. Although 
they produced no local lesions, both gentlemen, after about a week, 
suffered from slight fever, accompanied by headache and general 
depression. The inguinal glands became enlarged. In one case the 
gland attained the size of a walnut, and it was so tender as to render 
walking painful. The general symptoms subsided after a few days, but 
the glands remained swollen for some weeks, although they were 
not painful after the first few days. Dr Hindle Avas subsequently 
bitten by these ticks, but there was no recurrence of the symptoms above 
described, this apparently indicating an acquired immunity to the 
effects of the bites. 
That untoward effects occasionally follow the bites of Argasid and 
Ixodid ticks has been recorded by me elsewhere-; these effects are, 
hoAvever, not to be confused with the subsequent development of a specific 
1 The absence of any after-effects on this occasion may have been due to acquired 
immunity. G. H. F. N. 
^ Nuttall (1899), Johns Hopkins Hospital Reports, vm. 42; (1908) Journ. Roy. Inst. 
Pull. Health, xvi. 14; (1908) Ticks, Part ,i. pp. 81 etseq.; (1911) Ticks, Part ii. p. 313 
(in press, see regarding the effects of Ixodes ricinus bites). 
