HEMATOZOA. 



487 



HEMATOZOA. 



The circulatory apparatus of subjects belonging to several anincial 

 species, especially the dog, may lodge numerous helminths, for in- 

 stance : 1. Filaria immitis; 2. Hœmatozoon suhulatum — Leisering, 

 or Strongylus suhulatus — Cobbold ; 3. Pseudalius inflexus (found in 

 a seal by Heriug). 



The most important species is the cruel threadworm {Filaria 

 immitis), the discovery of which is erroneously attributed to Leidy, 

 of Philadelphia (1858), for this worm is identical with the Filaria 

 papulosa hœmatica, described by Delafond and Gruby. Accord- 

 ing to Krabbe, the adult threadworms reach a length of 15 to 30 

 centimetres and a thickness of 1 millimetre. We have found 

 specimens measuring 85 centimetres. Oreste has found 75 thread- 

 worms in the right heart, where they had determined an obliter- 

 ating thrombosis like those observed in the pulmonary artery 

 (Serres). In the left heart they may also produce obstruction of 

 the auriculo- ventricular orifice (Silvestri). The embryo of the 

 threadworm has been found in the blood of the dog by hundreds 

 of thousands (Delafond and Gruby) ; their average length is one- 

 fourth of a millimetre and their thickness 5 fi. 



Symptoms. As a rule, threadworms do not occasion any serious 

 trouble, even when the blood contains them in large quantities. 

 In some cases, though, they produce fatal accidents (apoplectiform 

 death), either in determining thrombosis of the heart and obstruc- 

 tion of its orifices, or in forming miliary emboli in the encephalic 

 capillaries. We have besides observed epileptiform convulsions, 

 dyspnœa, emaciation, great weakness, hemoptysis, enterorrhagia, 

 and even rabiform symptoms. 



Treatment. It would be illusory as long as the entrance-door 

 of the parasite remains undiscovered. Were this known it would 

 undoubtedly be possible to make some prophylaxis. Hereditary 

 transmission of threadworms is very doubtful ; possibly association 

 with infected animals may cause contamination of young dogs. 



According to Manson, the mosquitoes of the tropical regions of 

 the New World ingest the embryo of the threadworm along with 

 human blood ; they become, therefore, the intermediary host of 

 the Filaria sanguinis hominis. From the stomach of the mosquito 

 the worm penetrates into the thorax; its migrations then cease, and 



