101 



trypanosomiasis with heavy mortality do not occur, but this is not 

 the case among horses, especially imported animals. No appreciable 

 harm seems to be caused to native stock in the fl\^ areas, so that it 

 would appear to have acquired a high degree of resistance. 



The three types of trypanosomes in the Northern Territories are 

 Trypanosoma hrucei {pccaitdi), T. vivax {cazalboni) and T. congolense. 

 In horses the symptoms are nearly alike for all three, but infection 

 due to T. vivax is not so severe as that caused by T. bnicei, and most 

 of the recoveries that do take place occur after T. vivax infection. 

 In cattle T. vivax does not appear to do much harm, and no symptoms 

 were observed. T. hnicei is said to cause a sudden emaciation that 

 lasts for a year, after which the health of the animal improves. 

 T. congolense hitherto has only been found naturally in horses, but 

 experimentally it is very fatal to sheep, goats and dogs. 



Stomoxys spp. are met with wherever there is live-stock, the most 

 common being S. calcitrans, which is confined to the villages, and, 

 as a rule, does not follow cattle out to grass. In 1912 the author 

 attributed the spread of trypanosomiasis among horses at Accra to 

 Stomoxys and Lyperosia found in the district [R.A.E., B, ii, 48]. 

 Given a reservoir of infection, Stomoxys seems capable of maintaining 

 an enzootic centre in an area. These flies also act as carriers of two 

 worms, Hahronema microstoma and H. macrostoma, found in the 

 stomachs of horses and donkeys. 



The common Hippoboscid is Hippobosca maciilata, which is said to 

 be capable of transmitting trypanosomiasis mechanically, like Stomoxys. 



Many species of Tabanids occur and cause annoyance to cattle. 

 They are also believed to maintain an enzootic centre of trypano- 

 somiasis by mechanical transmission. 



The following ticks occur in the Territories: — Amhlyomma splen- 

 didum, fairly rare, found on cattle ; not known to transmit disease. 

 A. variegatum, common, found on cattle and sheep, to which, however, 

 it does not appear to transmit any specific disease. Margaropiis 

 {Boophiliis) annidatus australis, common, found on cattle, transmits 

 redwater. B. annidatus decoloratus, very common, found on cattle, 

 sheep and goats, conveys redwater and also, it is said, spirochaetosis 

 in cattle. Haemaphysalis leachi, found on carnivora, especially dogs, 

 rarely on cattle, sheep, goats and horses ; transmits canine piro- 

 plasmosis. Hyalomma aegypticimi, common, found on all domesti- 

 cated animals, transmits bovine redwater. Rliipicephaliis sanguineus, 

 common, found on dogs, sheep and goats ; transmits canine piro- 

 plasmosis. R. simits, common, found on cattle, and being a trans- 

 mitter of African Coast fever, would become a serious factor should 

 this disease be introduced. 



The onh' method at present adopted for ridding the country of ticks 

 is to burn the pastures at a certain time of the year, but this is unsatis- 

 factory. Stunting of growth, decreased milk yield, and marked 

 depreciation of the hides are the results of tick infestation. 



The commonest forms of piroplasmosis of cattle in the Northern 

 Territories are those due to Piroplasma higeminum, Theileria mutans, 

 and a third parasite, Achromaticiis [macfiei] [R.A.E., B, viii, 62]. 

 These parasites set up only benign affections, inasmuch as all calves 

 become infected shortly after birth. 



The horse is also said to be subject to infection with Nuttallia equi, 

 producing a dangerous and frequently fatal anaenna. Up to the 

 present time piroplasmosis has not been detected in sheep. 



