Neurocysticercosis

[hazelm]

How, pray tell, do tapeworms / or tapeworm larvae get inside the brain?

 

https://www.sciencedaily.com/releases/2017/11/171130141229.htm

[exchemist]

How, pray tell, do tapeworms / or tapeworm larvae get inside the brain?

 

https://www.sciencedaily.com/releases/2017/11/171130141229.htm

As I recall, from an excellent book called Animals Without Backbones, now sadly out of print, which I read as a fascinated child, the lifecycle of the tapeworm involves eggs hatching in the intestine and the larvae then migrating into various body tissues where they go dormant as cysts. This is the reason why one traditionally ensures pork is well cooked, to avoid the risk of ingesting cysts. When the cysts are inadvertently eaten, the next phase of the lifecycle is triggered: adult worm grows from them and hooks onto the intestine of the host.

 

I presume that sometimes these larvae can reach the brain.

[hazelm]

As I recall, from an excellent book called Animals Without Backbones, now sadly out of print, which I read as a fascinated child, the lifecycle of the tapeworm involves eggs hatching in the intestine and the larvae then migrating into various body tissues where they go dormant as cysts. This is the reason why one traditionally ensures pork is well cooked, to avoid the risk of ingesting cysts. When the cysts are inadvertently eaten, the next phase of the lifecycle is triggered: adult worm grows from them and hooks onto the intestine of the host.

 

I presume that sometimes these larvae can reach the brain.

Exactly as you say.  What is puzzling me is how they get past the blood/brain barrier.  According to the story, it is only the larvae cysts that do but those have a bit of size to them.  I just remembered something.  Somewhere I have a letter from a neuroscientist that tells me what can pass that barrier.  I shall go looking for that. later  I know it was about how the barrier filters the blood that enters the brain.

 

Thanks for reply.

[exchemist]

Exactly as you say.  What is puzzling me is how they get past the blood/brain barrier.  According to the story, it is only the larvae cysts that do but those have a bit of size to them.  I just remembered something.  Somewhere I have a letter from a neuroscientist that tells me what can pass that barrier.  I shall go looking for that. later  I know it was about how the barrier filters the blood that enters the brain.

 

Thanks for reply.

I wouldn't have thought the blood/brain barrier would be relevant to a larva. The barrier is a chemical barrier that prevents certain classes of chemical species from crossing. A larva physically burrows, so it would not be impeded. 

[hazelm]

I wouldn't have thought the blood/brain barrier would be relevant to a larva. The barrier is a chemical barrier that prevents certain classes of chemical species from crossing. A larva physically burrows, so it would not be impeded. 

Oh!  I have it backward?  Larvae burrow, yes.  But they are inside a blood vessel? 'I'll find that letter before the day is over.

 

By "chemical species", do you mean "certain chemicals"? 

 

Thanks

Edited December 1, 2017 by hazelm

[exchemist]

Oh!  I have it backward?  Larvae burrow, yes.  But they are inside a blood vessel? 'I'll find that letter before the day is over.

 

By "chemical species", do you mean "certain chemicals"? 

 

Thanks

Ouch, yes I meant certain chemicals.

 

I am not sure whether the larvae make their way in the blood vessels or through the tissues. But either way, there is no reason to think they could not penetrate the barrier. 

 

By the way I have found Animals Without Backbones again and have ordered myself a copy. If it has more about this I'll try to remember to post it here.  

[hazelm]

Ouch, yes I meant certain chemicals.

 

I am not sure whether the larvae make their way in the blood vessels or through the tissues. But either way, there is no reason to think they could not penetrate the barrier. 

 

By the way I have found Animals Without Backbones again and have ordered myself a copy. If it has more about this I'll try to remember to post it here.  

Thank you.  That will be good.