Look on the Bright Side

Having a toothpick fish (the Candiru) take a detour up your urethra doesn’t really bear thinking about. The idea of maggots crawling around under your skin sickens you. It is true, humans are afflicted by some pretty nasty parasites. At least we can be thankful for bacon.

But things could be much, much worse.

Imagine a parasite that alters your appearance so that you look like food for something higher up in a food chain you have no place being in. That is exactly what happens when an Amazonian nematode infests an ant called Cephalotes atratus – the nematode turns their abdomens into juicy red berries that birds can’t resist. The nematode then gets a free ride all around the jungle.

A similar thing happens to snails infected by the trematode flatworm Leucochloridium paradoxumthe developing trematode offspring engorge the eye stalks of the snail making them look like pulsating green delicacies.

Or imagine you’re a builder and something comes along and deposits its larvae inside of you. These larvae take over your ‘mind’. You stop your current building projects, and before your impending death the larvae force you into building them a nice home to live in.

No, this isn’t science fiction, this is what happens when the web-building spider Plesiometa argyra is parasitised by the larvae of the wasp Hymenoepimecis argyraphaga. Another example of ‘arthropod mind control’ is the Nematomorph, or horse-hair, worm that makes grasshoppers jump into water – where they drown because they can’t swim (and the worm doesn’t bother to teach them)….

With the animal kingdom seemingly rife with ‘zombifying parasites’ (see the slide-show at Discover Magazine) it makes one wonder, are there strange parasites controlling what we do, that we don’t know about? Maybe that’s how we should view  self-destructive memes like suicide bombing and the acceptance of quackery – as parasites of the mind. Having a Baloney Detection Kit handy is a good way to keep these parasites at bay.

Actually there may well be at least one ‘real’ ‘zombifying parasite’ out there affecting mammals (including humans) – check out this fascinating conversation with Robert Sapolsky on ‘Toxoplasmosis and Free Will’ from Edge.

But for me there is one parasite scenario that ‘out freaks’ all others:

Imagine  a parasite that enters your body through your respiratory openings before latching onto the base of your tongue. Then, after snuggling into its new home, it feeds and grows by sucking the blood out of your tongue. Your tongue atrophies away to nothing. Then something truly weird happens. The parasite takes pity on you and actually replaces your tongue and does what your tongue once did!

For fish, this bizarre nightmare is a reality – the parasite is an isopod named Cymothoa exigua, the tongue-eating louse. This is believed to be the only example of a parasite the destroys a host organ then functionally replaces it.


So, remember, look on the bright side, OK?

Learn more about the wonderful world of parasites from Carl Zimmer (@CarlZimmer):

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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