permeability. Their color darkens; they become more or less im- 

 mobile and ususilly die in a little over a week. Those that live 

 fail to produce viable eggs. Application of 0.5 per cent gamme- 

 xane dust to floors and lower parts of walls sprinkled from per- 

 forated cigarette tins at the rate of three or foirr pounds of 

 dust per hundred square feet is recommended, but frequent checks 

 should be made where reinfestation is liable to occur (Jepson 

 1%7}. 



Application of Jepson 's findings on a township scale in 

 Tanganyika was described in detail by Knowles and Terry (1950) 

 using '*G dust'* (D220 compound one part, and diatomite four parts), 

 These authors found that although total eradication is probably 

 impossible, a townshipwide control program can almost eliminate 

 relapsing fever in a fairly static population and is much cheaper 

 than hospital treatment of the disease. Sampling methods and 

 application methods were also stressed. 



Factors to be considered in a control program and need for 

 further research were discussed by Phipps (1950), who indicated 

 the necessity of using tested diluents and making accurate sur- 

 veys before and after treatment.' The incidence of ticks and dis- 

 ease should also be checked before large scale programs are 

 instituted for, in Phipps' opinion, not all places in which ticks 

 abound are disease foci. 



In Annecke and Q,uin*s (1952) extensive chemical control 

 program on a heavily infested South African citrus plantation, 

 it was found that BH3 applied as a spray to inner walls of huts 

 in concentrations of 300 mg. gamma isomer (or upwards) per square 

 foot (emulsion of 1% BW with 0, gamma isomer) gave effective 

 control. With lesser concentrations, tick populations increased 

 rapidly after seven weeks. Surviving ticks from sprayed huts 

 deposited considerably fewer eggs than normal females. 



Nevertheless, the same authors report, reintroductions were 

 so frequent that the authorities finally resolved to construct 

 tickproof habitations. In spite of comparatively high initial 

 cost in comparison with daub and wattle huts, this was found to 

 be the only realistic approach to reducing deaths and man hours 

 lost to relapsing fever. 



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