PARASITES AND PARASITIC DISEASES 229 



PROTOZOAN DISEASES 

 Trypanosomiasis is the term used for those diseases caused by 

 infestation with the Trypanosomes. There are several varieties 

 of these protozoan parasites. They are found free in the blood- 

 plasma and cause fever, loss of flesh, and progressive general 

 anemia. Dourine is a typical protozoan disease. It is transmitted 

 by sexual intercourse, so is described with the communicable dis- 

 eases in Chapter XXI. Surra affects horses and other animals in 

 tropical countries. The Trypanosoma evansi causes surra. Flies 

 are known to be the carriers of the surra parasite. 



WORMS 



Round-worms are easily identified by the shape of their bodies 

 and the complete digestive apparatus with which they are always 

 provided. A number of different species are found inhabiting 

 organs of the digestive, respiratory, and circulatory systems. 

 Some are so minute as to be almost invisible to the naked eye, 

 while others attain a length of 12 inches or more when fully devel- 

 oped. They cause damage by interfering with the functions of 

 the infested organs. The effects are unthriftiness, emaciation, 

 diarrhea, anemia, and even death. Among the most common 

 forms infesting the horse are the Sclerostoma tetracanthum (blood- 

 sucking worm), Sclerostoma equinum (palisade worm), Oxyuris 

 curvula (pin- worm), and Ascaris megalocephala. 



The Ascaris megalocephala is the large white worm so fre- 

 quently seen in the feces. The male of this variety measures from 

 6 to 10 inches long, while the female may exceed 14 inches in length. 

 They produce digestive disturbances, and may even mechanically 

 clog the intestines if present in large numbers. A diagnosis is 

 made by finding one of the adults or its eggs. A successful remedy 

 to rid animals of these and other worms of the intestinal canal is 

 1 quart of raw linseed oil mixed with 2 or 3 ounces of oil of turpen- 

 tine. This mixture is to be given in one dose on an empty stomach. 



Tapeworms have fiat, ribbon-shaped, segmented bodies and 

 sucker disks by which they attach to the lining of the intestine. 

 These parasites are only rarely met with. Instead of a digestive 

 apparatus, tapeworms are provided with minute openings in the 

 cuticle through which nourishment is absorbed. Each segment is 

 capable of self-fertilization, for it is a hermaphrodite, possessing 

 both male and female genital organs. 



