ORNITHODOROS' 



INTRODUCTION 



Both important African species of Ornithodoros , 0. moubata 

 and 0, savignyi, occior in certain areas of the Sudan, where they 

 are known as halm ( p — ^>fl ), From two to five other species 

 indubitably exist in the Sudan but have not yet been found there. 

 Approximately fifty species comprise the genus throtighout the world, 

 0, laaubata is the most important tick vector of relapsing fever in 

 itfrica and its bite is often painful, 0, savignyi has been sus- 

 pected to be a relapsing fever vector ,- although incriminating evi- 

 dence in nature is negative or unconvincing. 



Ornithodoros ticks are thick, leathery, and podlike. They may 

 be more or less difficult to find but pain when they bite signifies 

 their presence. In contrast to Argas ticks, which usually parasitize 

 birds and bats, most Ornithodoros ticks parasitize mammals, including 

 bats, and only exceptionally attack birds, reptiles and amphibians. 



The two species under consideration represent a somewhat more 

 advanced stage in evolution of parasitism than do Argas and other 

 Ornithodoros species in that their larvae remain in the large, 

 leathery egg until ready to make the larval— nymphal^ molt. The 

 safety of the tough egg capsule affords delicate larvae considerable 

 protection from the elements. 0. rooubata and 0. savignyi are un- 

 usiial in this respect; larvae of most other Ornithodoros species are 

 active and feed from ajiimal hosts. Shortly after hatching larvae 

 molt to nymphs that soon set out to find a host. Nymphs and adults 

 feed rapidly, in a matter of a few minutes to an hour or two, and 

 are seldom transported while feeding on the host. They are, there- 

 fore, usually found only in their resting places, Ornithodoros 



*Some writers replace the os ending used here by us. The original 

 name used by Koch (18/^4- J was spelled with an os ending, and this is 

 generally though not universally conceded to conform to the rules 

 of nomenclature axid of philology. This question has been reviewed 

 by Najera (1951 ). 



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