Dissimilarity of frequent hosts from area to area is apparent. 

 Obviously, the numbers and kinds of available animals vary over the 

 great area infested by this tick and different climatic and ecolog- 

 ical conditions affect the parasite's life cycle and its relation 

 to different hosts. In certain areas, physiological races special- 

 ly adapted to feeding on certain hosts may exist. 



It appears well established (l) that domestic dogs are most 

 frequently parasitized by R. s. sanguineus (though in tropical 

 and southern Africa, Haemaphysalis 1. leachii is often more common 

 on dogs), (2) that parasitism of large groundfeeding birds, hares, 

 hedgehogs, and domestic sheep and goats is common, (3) that all 

 wild carnivores within the tick's range are frequently though 

 seldom heavily parasitized, and (A.) that wild ruminants and man 

 are only erratically chosen as hosts. Wild animals in zoological 

 gardens and others living vmder domestic conditions, especially 

 when in manraade buildings or enclosiires, are particularly sus- 

 ceptible to attack by this parasite. 



Human Hosts 



Available information on human parasitism by the kennel tick 

 is difficult to evaluate. From accoxmts of this species in rela- 

 tion to boutonnevise fever in northwestern Africa and in southern 

 Europe, it would appear that human beings are more frequently 

 bitten in these areas than elsewhere in Africa. There is, however , 

 no conclusive evidence , as yet , that this is true . The considerable 

 kennel tick populations "In North Africa and the density and intimacy 

 of human beings and their domestic animals may be responsible for 

 the greater incidence of human infestation in this area, as sug- 

 gested by Philip (1952). At the same time consideration should 

 be given to the possible existence of a biological race with a 

 greater predilection for feeding from man. 



In tropical and southern Africa, though isolated reports of 

 parasitism of man exist, only Roberts (1933) and workers of his 

 period in Kenya have published accounts of serious infestation. 

 On one occasion boutonneuse fever, attributed to R. sanguineus 

 but without biting specimens, was so prevalent that it caused 

 disorganization of staffing arrangements of the Kenya and Uganda 

 Railways. Roberts stated that when the land is covered by stand- 

 ing water these ticks seek shelter in houses and human inhabitants 



- 69A - 



