Etiology, Pathogenesis, Anatomical Changes. 903 



fetus through the placental vessels. This however was not con- 

 firmed by Rosso in experiments with a bitch. 



Accordiug to Manson the embryos of the filaria sanguinis hominis, a worm 

 resembling the filaria of clogs, are taken up by mosquitoes (culex mosquito) with 

 the blood of affected persons, in which they develop to larvae. When later the 

 mosquitoes die in the marshes, after depositing their eggs, the young filaria are 

 set free from their bodies, and may reach the stomach of new victims with the 

 water, and from there gain the blood vessels of man. A similar development of 

 the filaria immitis would also be expected, but Grassi proved that the majority 

 of the embryos of the filaria sanguinis hominis die in the intestinal canal of 

 mosquitoes, and that the filaria immitis cannot live in fleas and lice of dogs. Grassi 

 therefore Ijelieves that the embryos reach the water with blood from occasional 

 wounds, and probably also with the urine, passing into the healthy animals directly 

 with such infected water. 



Pathogenesis. The sexually mature filaria appear to cause 

 disturbances, especially in a mechanical way. They check the 

 blood circulation more or less, depending on their numbers, 

 either in the heart itself or in the blood vessels, with which 

 of course a quite considerable thrombosis produced by the 

 parasite usually becomes associated. After their infesting the 

 heart cavities the filaria produces a chronic inflammation of 

 the endocardium. The thrombi which develop in the heart 

 cavities or in the large blood vessels may again give rise to 

 the dissemination of emboli. The formation of emboli occurs 

 mostly in the branches of the pulmonary arteries, and may 

 then lead to necrosis of circumscribed portions of the lungs 

 or to abscess formation. Particles of the thrombi are excep- 

 tionally conveyed to the kidneys or into the brain. 



The embryos of filaria produce first of all anemia with a 

 pronounced leucocytosis, the severity of which depends on the 

 number. These changes in the blood are probably brought 

 about by the action of toxic metabolic products, and also by 

 the utilization of the constituents of the blood. The purely 

 mechanical action of the embryos produces on the other hand 

 at most only insignificant effects, plugging of the capillaries, 

 and occurs most frequently in the capillaries of the kidneys, 

 more rarely in the other organs (lungs, brain). 



Anatomical Changes. Sexually mature filaria surrounded 

 with firm blood coagulum are found in the right half of the 

 heart or in any branch of the pulmonary arteries, sometimes 

 in the vena-cava, and exceptionally also in the left half of 

 the heart (Hutyra found in one case almost the entire aorta 

 filled up by firm masses of thrombi). At the same time chronic 

 endocarditis, partial hypertrophy and dilation of the heart, 

 possibly also rupture of the heart, with symptoms of blood 

 stasis (hydrops, cirrhosis of the liver, etc.) may frequently be 

 present. The lungs sometimes show hemp-seed to pea-sized 

 nodules, each containing an embryo appearing as a red dot; 

 besides these atelectasis, splenization, abscess formation or 

 necrosis may be found. The kidneys may manifest a paren- 



