TED video including ant brain flukes!

[Mike B in OKlahoma]

http://www.ted.com/index.php/talks/view/id/116

Ken Ramos has posted links to some TED videos before. This one includes Dan Dennett talking about memes, and includes a brief discussion of those ants that crawl up on grass....

[Ken Ramos]

I like TED, there are so many interesting speakers on the site. This guy has got quite a bit of food for thought, literally. I have listened to a number of lectures given my Richard Dawkins but somehow I have missed out on the "memes." More than likely in his books and not in lectures he mentions them. Anyway and interesting talk and unusual information on flukes and ants. Reminded me of Summit Disease there for a moment. Thanks Mike.

[Planapo]

Thanks Mike, for the link and for spreading these memes!

It´s interesting to hear how this philosopher is taking up and transferring evolutionary thought and Dawkins' ideas further to human sociology.
And it's good to see that evolutionary thought is spread in the U.S., because sometimes when one hears that evolution as a topic is banned from curricula of some schools in your country, one is concerned.

And yes, the analogy Ken was immediately reminded of, namely between the insect´s behaviour when infected with summit disease or with Dicrocoelium is a well known phenomenon in evolutionary parasitology: a parasite altering a host´s physiology/behaviour/morphology so that the likelihood of spreading to a further host is increased. It is easy to see that this is favoured by natural selection.

BTW, unlike partly in the video, Dicrocoelium dendriticum is usually not called a 'brain fluke' but the lancet or little liver fluke as the actual flukes (i. e. the adults that are able to reproduce sexually) live in the bile ducts associated with the liver of their final herbivore host. The larva of Dicrocoelium that encysts in the ant's suboesophageal ganglion is sometimes referred to as ‘brain worm’. The infected ant climbs on top of herbs or grasses where she bites into the plant, and then her mandibles are spasmodicly locked, so that the ant is fixed there and then, hopefully from the parasites´ perspective which are inside the ant, will be eaten by a final host. The full complexity of the life cycle of D. dendriticum with ants as second intermediate hosts was discovered in Germany by W. HOHORST around 1960 when working for Hoechst AG (that some time ago merged in Aventis). Now you can imagine why many German students of biology, vet. medicine, medicine and pharmacy should be quite familiar with Dicrocoelium.

--Betty

[Ken Ramos]

Okay Betty you got me hooked. So how does the lancet or "little liver fluke," affect the final host and how is it passed on, through the uninary tract or digestive? I take it that humans can get this thing too. If so how by consuming flesh from the infected host?

[Planapo]

Ken,

Dicrocoelium flukes in the final host lay eggs that are released with the host's faeces. In Dicrocoelium (note there are other liver flukes with different life cycles) the eggs must the be eaten by certain land snails to undergo further development.
It is reported that man can be infected with Dicrocoelium, which then develop as flukes in the bile ducts. This rarely happens as for such a case infected ants or parts of such an ant containing parasite larvae have to be ingested. In the infected final host the adult flukes may cause some irritation, to some extend probably weakening the host. But in mild forms of the disease, i. e. if not too many flukes inhabit the bile ducts, the infestation in livestock stays often unnoticed until the animal is slaughtered. The liver is then discarded. For parasitological courses flukes can be obtained from abattiors in areas where Dicrocoelium occurs in livestock.


There is another widespread liver fluke, Fasciola hepatica, that occurs in livestock. F. hepatica causes more damage than D. dendriticum as it can enter the liver parenchyma, causing what is among farmers known as 'liver rot' of sheep and cattle. F. hepatica can also infest man, but no ants are involved in its life cycle, as the larvae that have to be taken up orally by the final host, encyst directly on plant material. And it is reported that F. hepatica can cause trouble in humans in yet another way: When infested sheep or cattle liver that contains still living flukes, probably it is raw or undercooked then, is consumed, the flukes can attach with their suckers and spikes onto the mucosa of the patient´s throat.

Hoping to have satisfied some of your good curiosity. Aren´t these fascinating 'aliens' right amongst us?

--Betty

[Ken Ramos]

Betty wrote:

Hoping to have satisfied some of your good curiosity.

Yes you did and thank you!

Aren´t these fascinating 'aliens' right amongst us?

Indeed they are Betty. I often wonder why we are reaching towards the stars, when we seem to know so little about our own world sometimes but then again, science in its entirety is a collective venture. Thanks

[Mike B in OKlahoma]

Interesting stuff, Betty. I'm glad to hear that there's no danger of me crawling up on a blade of grass after ingesting some of these!

There's a lot to know about this old world....