B46 GEORGE H. F. NUTTxYLL. 



gorged, they remain in situ, undergo metamorphosis in turn and emerge as adults, 

 which promptly re-attach themselves. Copulation takes place upon the host. The 

 females lay some 1,000-2,500 eggs. 



This tick does not live long unfed, the larvae scarcely survive 90 days' starvation 

 and the other stages perish rapidly when removed from the host. The life-cycle from 

 egg to egg may be completed in 25 or more days. 



Hosts : cattle, although the species is occasionally found on other mammals. 



Relation to Disease : B. decoloratus commonly conveys bovine piroplasmosis 

 throughout tropical and southern Africa, this disease being caused by Piroplasma 

 bovis ( = higeminum) which multiplies in the blood corpuscles of cattle. When a female 

 tick imbibes blood containing this parasite she transmits it to her larval offspring. 

 Cattle usually show fever about 10 days after infestation with infected larvae. The 

 parasites now appear in the host's blood and re-infect the ticks as they attain maturity. 



Apart from fever, the affected cattle commonly show progressive emaciation, 

 anaemia, bloody urine, etc., as in dogs suffering from piroplasmosis (see p. 344), the 

 blood grows watery and the spleen becomes much enlarged. The mortality from the 

 disease may be very high, 40-100 per cent, of the affected animals, chiefly freshly 

 imported cattle, not infrequently dying. The persistence of the disease in nature 

 is explained (as in equine and canine piroplasmosis) by the fact that when cattle recover 

 they may continue (whilst apparently in perfect health) to harbour the parasites in 

 their blood for years. The apparently immune indigenous cattle are really all infected 

 and serve as " reservoirs " for the Piroplasma, which are taken up by the Boophilus. 



Piroplasmosis in cattle may be successfully treated by the intravenous injection 

 of 200 cc. of a 1*5 per cent, aqueous solution of trypanblue (Nuttail and Hadwen). 

 Animals which have recovered under this treatment are in the same condition as 

 " salted " animals, i.e., those that have recovered under natural conditions. Cattle 

 treated with trypanblue (as also dogs) continue to harbour the parasites in their 

 blood. 



Eradication : This is the tick which has been most successfully eradicated by 

 dipping processes and changing the pasturage of susceptible animals. Many thousands 

 of square miles have been rid of the tick and the disease by these measures in the 

 United States, South Africa and Australia. 



Hyalomma aegyptium occurs throughout Africa, in Southern Europe and many 

 parts of Asia, notably in India. The tick may require either two or three hosts. The 

 female lays 10,000 to 15,500 eggs, which take 35 days to hatch at 18° C. The larvae 

 become engorged in 4-15 days, when they frequently drop off to undergo metamor- 

 phosis ; others may, however, whilst remaining attached to the host, undergo 

 metamorphosis in situ and emerge as nymphs, which quickly re- attach themselves, 

 and, after feeding to repletion, drop to the ground to undergo metamorphosis to adults. 

 Where the larvae and nymphs remain attached to one host, the gorged nymphs drop 

 off 25-46 days after they were put on the animal as unfed larvae. Females remain 

 6-8 days upon the host, whereas the males may remain anchored for months in the 

 same spot where they previously copulated. There are about three times as many 

 females as there are males. 



