208 TROPICAL MEDICINE AND HYGIENE 



These ticks belong to the division Argasina, and these differ 

 from the ordinary cattle and dog ticks, Ixodina, in that the 

 mouth is on the under or ventral surface of the body, that 

 there are no dorsal or ventral chitinous plates or shields 

 either in the male or female, that the last joint of the palpi 

 is quite distinct and that the palpi are not grooved nor do 

 they form a sheath for the rostrum. The young also have 

 four pairs of legs when they emerge from the egg. 

 In habits also they differ, as they do not remain firmly 

 attached to their host, but after feeding leave him 

 and may feed on many individuals, as they live for 

 months or years. They feed at night mainly. They 

 inhabit houses, living in the dry dust so abundant in 

 houses with mud floors, or in thatch or reeds of which 

 the roof and walls are composed. The ticks which feed 

 on infected persons do not themselves necessarily become 

 infective, as the infection is transmitted to the progeny, 

 and therefore if a tick feeds on an infected person it may 

 be many months before the progeny of these ticks can 

 infect a susceptible person. Another point is that from 

 an infected tick many infective ticks may be derived. 



The problem differs therefore in many important 

 respects from prophylaxis against malaria. Destruction 

 of these ticks may be attempted but is difficult to carry 

 out, as in a country like Africa, where termites (white ants) 

 are so destructive, wooden floors and walls are imprac- 

 ticable. Mud floors, reed and thatched walls and roofs 

 cannot be thoroughly cleansed. Even in European 

 houses as little woodwork as possible should be used, 

 but with cement floor, brick walls and galvanized iron 

 roofs there is little danger of the 0. monbata being 

 present. 



Prophylaxis for Europeans is fairly easy. In travelling, 

 native huts should be avoided, even if they have not been 

 occupied for many months. The 0. moubata cannot 

 climb up a smooth vertical surface, so that even in a 

 native hut if a camp bedstead be used and no part of the 

 bedding be in contact with the walls little risk is run. 



