74 SANITARY ENTOMOLOGY 



Dirofilaria repens, Railliet and Henry, 1911 



In the adult stage this nematode, wliich is a very similar parasite to 

 D. immitis, occurs in the subcutaneous connective tissue of the dog. Its 

 larvae enter the blood stream whence they are liable to be ingested by 

 blood-sucking insects. According to Bernard and Bauche (1913) the 

 vellow fever mosquito Aedes argenteus {Siegomyia calopus) acts as the 

 intermediate host. These investigators while admitting that other species 

 of mosquitoes might act as intermediate hosts of D. repens, found that 

 A. argenteus best fulfilled the natural conditions for the transmission 

 of the parasite, and their experiments were carried out with this species 

 of mosquito. They followed the various stages in the development of 

 the larval nematodes in mosquitoes fed experimentally upon infested dogs. 

 About 2 days after the mosquito has been fed the nematode larvae leave 

 the lumen of the alimentary tract and penetrate into the Malpighian 

 tubules where they undergo most of their growth and development. By 

 the eighth day the larvae may be found in some cases to have migrated 

 into the body cavity and thoracic muscles and the last stage of develop- 

 ment in mosquitoes may be found in the proboscis as early as the ninth 

 day. Six young dogs (10 days old) were submitted to the bites of 

 A. argenteus (fed 10 to 15 days previously on infected dogs) every morn- 

 ing for fifteen days. Six young dogs of the same age were kept as con- 

 trols, not exposed to mosquito bites. The bitten dogs all died within 

 thirty days. Ecchymotic spots were found beneath the skin at the points 

 of the mosquito bites, but no filarias were discovered. The other dogs all 

 survived the experiment. Under natural conditions the youngest dogs 

 found infested with D. repens by Bernard and Bauche were at least a 

 year old, hence the writers conclude that the development of the parasite 

 is very slow. Although they did not succeed in completing their experi- 

 ments by recovering the adult stage of the parasite in dogs, following 

 bites by infected mosquitoes, it appears safe to conclude that D. repens 

 is transmitted by mosquitoes in a manner similar to that in which D. 

 immitis is transmitted. 



Acanthocheilonema perstans (Manson, 1891) Railliet, Henry and 



Langeron, 1912 



This parasite occurs in man in tropical Africa and British Guiana, 

 the adults in the intraperitoneal connective tissue and fatty tissue of the 

 abdominal viscera and pericardium, and the first-stage larvae in the 

 blood stream. The larvae exhibit no periodicity in their appearance in 

 the circulation, the name perstans having reference to this fact. 



Christy (1903) has suggested that Ornithodoros monbata may act as 



