304 SOME MINUTE ANIMAL PARASITES 



as just mentioned, are not limited to the numbers of 

 deaths actually due to them. There are recoveries 

 or partial recoveries known, and such cases remain 

 usually with a lowered vitality. The race thus tends 

 to become enfeebled, and often lacks the initiative to 

 better its conditions, so that after an epidemic of 

 disease there seems to be a tendency to degeneration, 

 rather than to improvement, among the survivors of 

 the more primitive tribes. 



The great importance of the parasitic Protozoa in 

 relation to human disease is evident, and they are 

 also important in connexion with the food of man. 

 When redwater and coast fever were discussed 

 (Chapter IX.), the monetary losses due to the death 

 of cattle in the United States alone were estimated 

 at 8,500,000, and that sum would be enormously 

 increased were the world's losses due to protozoal 

 cattle diseases estimated. Redwater fever is a 

 serious menace, coast fever cuts off both food 

 and means of transport; but they are not alone. 

 Surra, in India, due to Trypanosoma evansi, causes 

 much damage/- Nagana, in South Africa, kills cattle 

 and horses alike. Sheep perish from the attacks of 

 Babesia ovis. Goats die of heartwater, which is 

 spread by ticks, and is considered by some to be due 

 to an undetected Protozoon. Coccidiosis slays cattle 

 in East Africa, and the same disease destroys game 

 birds and poultry, such as fowls and turkeys, while 

 rabbits also are badly infested in some places. 

 Spirochaetosis is rampant among fowls in Egypt 

 and the Sudan, and epidemics among geese and 

 ducks occur in Russia. Apart from frequent deaths, 



