522 PROTOZOAL DISEASES. 



fever. I have not seen similar paroxysms and remissions in the malarial 

 fevers of horses. 



The bilious symptoms often seen in cases of malarial fever are chiefly due 

 to the bile of the patient co&taining an abnormally large amount of 

 bilirubin, which is the bile pigment that gives a yellow colour to the skin 

 and other tissues in jaundice. As bilirubin is produced by the decomposi- 

 tion of hsemoglobin, it follows that the more free hsemoglobin there is in 

 the blood, the greater will be the quantity of bilirubin in the bUe. In 

 malarial fever the blood becomes loaded with free hsemoglobin, owing to 

 the destruction of red corpuscles by the malarial parasites. 



The chief breeding-places of mosquitoes are shallow pools which are not 

 large enough to contam fish, and do not dry up between showers. Hence, 

 the best way to rid a district of mosquitoes is to drain or fill up these 

 pools, or to destroy the mosquito larvae by pouring into these pools a 

 suflScient quantity of paraflSn oil to cover their surface ; and to kill all 

 the mosquitoes within reach. A large number of the mosquitoes which 

 infest houses, can generally he found resting on the walls in the interior of 

 these buildings during the day. 



Colonel A. H. Morris, who is in charge of the Northern Territories of the 

 Gold Coast, reports : " I caused all holes which might contain puddles, and 

 so become breeding-grounds for the anopheles mosquito, to be filled up. 

 Some hollows in rocks, containing about 18 inches of water, were discovered 

 filled with thousands of larvae. The Hausas' and Carriers' lines were in- 

 spected twice a week in order to ensure no. stagnant water being allowed 

 to remain in old pots or tins. The general result has been an immense 

 reduction in the number of mosquitoes." 



Sir W. B. Kynsey states that in Havana, yellow fever was endemic for 

 a century and a half. During the past year it has been freed from the 

 scourge by killing the mosquitoes in the neighbourhood of each focus of 

 disease as discovered, and by carefully disinfecting every house that had 

 lodged a yellow-fever patient, in order to destroy the mosquitoes that had 

 bitten a sick person. 



The breaking up of ground for the construction of roads, etc., in tropical 

 countries, is often followed by outbursts of malarial fever, probably on 

 account of the formation of pools of stagnant water. 



Piroplasmosis, Biliary Fever, Tick Fever. 



OCCURRENCE AND SYMPTOMS.— For many years, veterinary 

 surgeons have known that horses in certain feverish districts of 

 India, such as Bengal and parts of the North-West, become occa- 

 sionally affected with a low type of fever, in which there is great 

 debility, with loss of appetite and condition. The pulse is feeble 

 and oppressed, though usually without much acceleration. I have 

 not observed any other signs of ill-health, except a rise in the 

 internal temperature. A few years ago, it was found that this 

 disease was caused by Piroplasma equi and P. caballi conveyed 

 by ticks. As a rule, it is not a serious disease, although cases now 

 and then terminate fatally. 



For a long time, a disease has been known in South Africa as 

 " biliary fever," which was regarded by many as the biliary form 

 of horse sickness (p. 464). The percentage of mortality from it 

 is small; it is as liable to affect horses in stables, as those at 



