Lizard ascarids indirect?! (Roundworms)

Stephen G. Kayes kayes at SUNGCG.USOUTHAL.EDU
Sun Sep 3 21:34:25 EST 1995


Hello, All:

	Can't speak about "all" Ascarids, but having worked with dog 
ascarids, Toxocara canis, and marine mammal ascarids (Anisakis simplex) 
the answer to the at large question of whether intermediate hosts is a 
genus thing, the answer is, "It definitely seems that way".  Toxocara is 
like Ascaris lumbricoides, in that infection is direct fecal-oral route.  
(actually there are some cool alternatives, but they are not relevant to 
this question).  Anisakis simplex, on the other hand requires 
intermediate hosts (typically fish) which are consummed by marine 
mammals.  If you think about it, if it were not for the intermediate 
hosts, the eggs passed in the feces would sink to the bottom of the ocean 
and marine parasitologists would become extinct.  The intermediated hosts 
keep the parasite eggs from entering the benthic layer.

	Steve
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On 3 Sep 1995, the End wrote:

> From Newsgroups: rec.pets.herp,sci.bio.herp,alt.med.veterinary
> Subject: Lizard ascarids indirect?! (Roundworms)
> ___________________________________
> Collegues,
> 
> Roger J. Klingenberg in his "Understanding Reptile Parasites"
> on page 51 states:
> 
> "Ascardis (Sulcascaris and Anqusticaecum in chlonians) are very
> common reptile parasites. They have an INDIRECT life cycle and require
> intermediate hosts. Roundworms are acquired by ingesting intermediate
> hosts such as frogs, fish, amphibians, lizards, rodents, and marsupials."
> 
> However, the human roundworm Ascaris lumbricoides has a direct life
> cycle.
> 
> Are these genus differences? Are there lizard roundworms with a
> direct life-cycle as well? Can insects serve as intermediate
> hosts in the above mentioned Ascarids?
> 
> E-mail replies only please,
> 
> Jim
> J. Graham PhD
> Biology Department 
> Washington University of St. Louis 
> 
> 



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