Friday, 10 April 2015

Cat lovers duped


"Cuteness, how adorable"....if you're thinking these thoughts then I may change your mind! (pun will become apparent).
I recently read about this insidious little parasite called Toxoplasma gondii who begins its life in a cats gut. I have two cats so I read on.

It seems this parasite is excreted by cats and is ingested into a host (sheep, cow, rat its not fussy) so it can survive. "The microbe is a single-celled pathogen that infects most types of mammal and bird, causing a disease called toxoplasmosis".
The studies looking at the effect Toxoplasma gondii has on rats and mice has been an interesting if not creepy read. It infects the brain of these unaware rats and alters their behaviour so they are no longer fearful of the scent of cat urine and instead seek it out. You can see there are no happy endings here; our risk taking rat becomes dinner to its alluring cat and the parasite has achieved its next goal to get back into the cat gut. It is only in the cat gut that Toxoplasma gondii can sexually reproduce.
There seems to be no definitive answer as to how this microbe is affecting the brain but Ingram et al (2013) found that rats that were treated for the parasite continued to show no fear of cats even four months after being parasite free, raising the further question of how it can sustain such long term effects with its physical absence.

Toxoplasma gondii can also infect humans (via cat litter & raw meat) and has been linked to personality changes which vary with gender; female hosts become "warmer and friendlier" and male hosts may be "more suspicious and antisocial" and take increased risks. Studies vary, some linking T.gondii with Schizophrenia and with high risk to the foetus during pregnancy.

So last week while reading Lyon et al (2007)  The Human Stain I was struck by their discussion of autonomy of self as being semi-permeable (p155) and their insistence of the credibility and importance of studying fruit flies and other species including bacteria for their lessons on how the human system works (p157 &158). Their proposition that research into bacteria has correlations with our own brain connectivity in signal transduction within our neurotransmitters and that we have much to learn from such research, seems to been vindicated in the research into T.gondii.

In the meantime, wear gloves in the garden and when emptying kitty's litter; which I suspect will become a pink job in my home at least!




1 comment:

  1. Dan Dennett's understanding of cultural evolution (memetics) bears some interesting parallels to this phenomenon, as outlined in this Ted talk: https://www.youtube.com/watch?v=KzGjEkp772s. FWIW I do not agree at all with Dennett here, and find it regrettable.

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