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the last session of the Legislative Council an Ordinance was pro- 

 mulgated [see this Review, Ser. B, ii, p. 203] making dipping com- 

 pulsory, where such is the wish of the majority. Since the blue tick, 

 Boo2)hilus decoloratus, is the principal disseminator of redwater, its 

 destruction will considerably reduce, if not entirely eliminate the 

 disease. This has happened on Bulawayo commonage and several 

 farms as the result of systematic dipping. 



In the case of East Coast fever, the tick mainly concerned is the 

 brown tick, Rhipicephalus appendiculatus, although other species, 

 such as the red-legged tick, R. evertsi, and the black-pitted tick, R. 

 simus, have also been incriminated. Unlike redwater, the East Coast 

 fever parasite is not passed through the eggs of the adult tick which 

 has imbibed infected blood and is therefore not transmitted by the 

 larvae hatching from such eggs. The brown tick belongs to the 

 class of interrupted feeders, larva, nymph and adult feeding on separate 

 hosts. The parasite having been taken up by a larva is transmitted 

 to a susceptible ox by the nymph, or, if by the nymph, is transmitted 

 by the adult, which may remain as long as fourteen months without 

 feeding. As the brown tick seeks different hosts in the larval, nymphal 

 and adult stages, and may escape from either in as short a time as 

 three days, fortnightly dipping does not avail against it. To eradicate 

 East Coast fever, a system of short interval dipping must therefore 

 be employed, whereby the animal is dipped at intervals of three or 

 five days. As a result of experiment the " Laboratory Dip," also 

 known as the " five-day dip," was evolved, and later on the com- 

 position was modified to form what was known as the " three-day dip." 

 The respective formulae are : — ^Five-day dip, 5| lb. soft soap, 2 gallons 

 paraffin, 8| lb. arsenite of soda (80 per cent, arsenic) and 400 gallons 

 water ; three-day dip, 3 lb. soft soap, 1 gallon paraffin, 4 lb. arsenite 

 of soda (80 per cent, arsenic), and 400 gallons water. 



Biliary fever of the horse is conveyed by the bite of the red-legged 

 tick, R. evertsi, which has also been accused of transmitting East Coast 

 fever and spirochaetosis of cattle. The adult may deposit several 

 thousand eggs, from which the larvae will emerge under favourable 

 conditions in about a month. They can live as long as seven months 

 without feeding, but having found a host, feed and remain on the same 

 animal as a nymph and drop off after a fortnight. After a quiescent 

 period of about twenty-four days, the adult emerges and is ready 

 to attach itself to a second host — another example of " interrupted 

 feeding." These ticks are generally met with in the ear and beneath 

 the tail, and are found on cattle, sheep, horses, mules, donkeys, goats 

 and many wild animals. The disease Imown as mahgnant jaundice 

 or biliary fever of dogs is transmitted by the dog tick, Haemaphjsalis 

 leaclii, which is also an interrupted feeder. If, however, the adult 

 female feeds on an infected dog, the parasite passes through the egg 

 stage but, although the larva and nymph do not transmit it, it is 

 carried through them to the succeeding adult. 



The danger of scalding in stock is avoided by gradually habituating 

 an animal to increasing strengths of dip. Well-bred calves especially 

 should first be dipped in a solution weaker than the three-day dip 

 until their skin becomes resistant. Animals which have been hustled 

 and are heated when passed through the dip are more liable to be 

 scalded. It is best to arrange the dipping at an hour when the animal 



