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Description — Like others of the family Strongyloides this species 

 occurs under two forms, a parasitic generation' and a. free-living genera- 

 tion. The parasitic adults are females only, reproducing parthenoge- 

 netically. They measure 2.2 mm. in length, four lips, oesophagus 

 one-fourth as long as body. Anus opens shortly in front of the 

 pointed end of the body; genital opening in the posterior third of 

 the body. Free-living adults are of both sexes. Males .7 mm. long, 

 posterior end rolled up to form a hook; the two spicules small and 

 much curved. Females 1 mm. long or a little more; tail end straight 

 and pointed. 



Life history — The parasitic forms bore into the intestinal mucosa 

 and deposit their segmenting eggs, 50-59 x 30-34,a in size. These 

 hatch out into the so-called rhabditiform embryos about .2 mm. in 

 length which grow to double or three times that size in the lumen 

 of the intestine end and are passed out with the feces. Under 

 favorable conditions they molt and become mature in a day or so, 

 copulate, and females deposit thirty to forty eggs from which there 

 develop a generation of free-living rhabditiform young. These molt 

 and transform into larvae which resemble the adults found in the 

 intestine. It is these "Strongyloid" larvae which infect man, either 

 by being taken in with water or food or by boring into the skin as do 

 the hook worms. 



Diagnosis — Examination of feces for the rhabditiform larvae. 



