ANIMAL PARASITES IN THE BLOOD 331 



The posterior portion of the male parasite shows a curvature 

 or spiral bending. The female gives birth to living embryo. 



The mature parasites live in heart (right half) in the major- 

 ity of infestations. The left heart and bloodvessels harbor 

 them in some cases. The number of parasites vary from a 

 few to several hundred. They are usually found entangled 

 in a round ball-like mass. The females give birth to embryos 

 which are each about j mm. long, and are set free in the blood 

 in large numbers. The sexually mature parasites may be 

 found at the same time in other parts of the body. The 

 manner in which infestation takes place has not been fully 

 proved. It is probably from the drinking water which 

 contains the larvae. These embryos reach the heart before 

 they mature. They may be discharged from the animal 

 either in the urine, nasal discharge, blood, or with the feces 

 and contaminate food or water again. 



Pathogenesis. The mature parasites located as they are 

 in the heart or large vessels produce more or less of a mechan- 

 ical disturbance in the action of those organs, or direct inter- 

 ference in the flow of blood through them. Formation of 

 emboli in the vessels, which often results, brings on various 

 complications in part due to necrotic foci in the lungs or other 

 organs. The presence of the embryos in the blood ultimately 

 leads to anemia with leukocytosis. 



Pathology. On necropsy the right heart is usually found 

 to be partially or completely filled with the parasites sur- 

 rounded by a coagulated mass of blood. The endocardium 

 is found more or less thickened and inflamed. The heart 

 is often dilated, the walls thin, and some cases ruptured. 

 Very frequently the lungs show small foci of necrosis, or 

 nodules in the center of which embryos are found. Similar 

 lesions occur in the liver, kidneys, skin and muscular tissues. 

 General anemia is present. 



Symptoms. The symptoms will depend a great deal upon 

 the number of adult parasites and embryos infesting the 

 circulatory system. When small numbers are present the 

 animal may not show any particular manifestations. When 

 the number is great, anemia and marked emaciation develop. 

 Hemorrhages are proved to appear in the mucous membranes, 

 skin, lungs, intestinal tract and other organs. 



