452 aENERAL DISEASES. 



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

 enough to contain fish, and which 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 larrse by pouring into these pools a sufficient quantity of 

 paraffin oil to cover their surface ; and to kill all the mosquitoes within reach. 

 A large number of the mosquitoes which infest houses, can generally be 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 inspected 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. R. Kynsey {" The Lancet," 9th August, 1902) tells us 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. 



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 occasion- 

 ally affected with a low type of fever, in which there is great de- 

 bility, 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, Dr. Lingard found that this disease 

 was caused by animalcula, closely allied to the producers of malarial 

 fever in man. As a rule, it is not a serious disease, although oases 

 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. 477). This supposition was ill-founded, 

 because the percentage of mortality from it was simall ; it is as liable 

 to affect horses in stables, as those at grass ; and it is resident in 

 localities where horse-sickness is unknown. Mr. D. Hutoheon, 

 C.V.S., Cape Town, tells us ("Veterinary Record," 5th April, 1902), 

 that " in the Cape Colony it is more prevalent in the Cape Penin- 

 sula, and along the East Coast, extending about 100 miles inland, 

 than elsewhere, but its area of infection has been increasing, and 

 cases are now met with all over the South African Colonies." Dr. 

 Theiler was the first to observe micro-organisms in the blood of 

 horses affected with this South African disease, and Mr. W. Robert- 

 son, M.R.C.V.S., in 1900, found in the red blood corpuscles of such 

 animals, protozoa closely resembling those of human malarial 



