The Eyes Have it!!!

As an undergraduate student taking Sherwin Desser's JZM252 parasitology course, I was fascinated by the nummber of "worm-in-the-eye" stories with which he regaled us. Loa loa, Onchocerca, Alaria, bot fly larvae, Toxocara (like Baylisascaris procyonis featured in an episode of House)... all potential eye parasites... ugh.
     I have often shown the image at right in public presentations about leeches. If you look closely you can see a Dinobdella ferox peeking out from behind someone's lower upper eyelid and it's back sucker holding onto the eyeball itself (the eye is upside down). This was sent to Gene Burreson by a physician in India many years ago, and it never fails to first confuse, and then disgust, a lunch-time scientific audience!
     The tribulations of people with leeches in their eyes continues. In regions of the world where the terrestrial leeches abound, like Australia and in the wet forests of Madagascar, leeches in the eyes and ears is all too common. Getting aquatic leeches in an eye, while less common, is perhaps more terrifying in light of the larger size of these "medicinal" leeches.
     The Australian story is remarkable for this misperception: "Dr Fogg says tweezers were not an option as simply pulling the leech off could leave its head lodged in the eyeball, leading to infection." Even if leeches had a head, which they do not, for this to be true, the head would have to embed, which it does not since the leech would be unable to suck blood without the seal it makes with its oral sucker.
     We might have Hollywood to blame for this. In The African Queen, Humphry Bogart's character Allnut (a Canadian, I might add), when he emerges from a swamp covered in leeches, declares to Rose (Katharine Hepburn), "No, no, don't touch 'em, don't! Salt, Rosie! ... You pull 'em off but their heads stay in! Poison the blood! Get the salt... If there's anything in the world I hate, it's leeches. Oooh, the filthy little devils."
     If you do get a leech in your eye, salt water will get it out. It will have to be saltier than your tears, so it's likely to sting, and you'll want to flush your eyeball with water afterwards.
     Every photograph of a leech in an eye is one where someone ran for a camera first instead of getting the thing out!

Marshal Brain - HowStuff(doesn't)Works

Marshall Brain, creator of HowStuffWorks (now a subsidiary of Discovery), which purports to be a clearing house of accurate technological information, badly mangles the truth about leeches in two podcasts: one on what is a medical [sic] leech and the other on how to remove a leech. In these uncited, apparently non-fact-checked articles (none of the leech biologists I know got a call), beyond the preposterous assertion that leeches look like slugs, Mr. Brain claims:
1) that leeches merely double in size when they feed (they can increase 5 times their weight or more).
2) that leeches raised in captivity are "sterile to a certain degree" (all leeches, wild or farm raised harbour Aeromonas in their crop; a course of antibiotics is recommended during post-operative leech therapy)
3) that they quickly attach and start feeding (far from true, especially in North America)
4) that leeches hold on with rows of tiny teeth (they hold on with their suckers, the teeth, far too small for holding onto anything, and which do not meet in any kind of bite, are used only for making incisions)
5) that removal of leeches requires one "to rip the teeth away from your skin" (in fact all that is needed is to gently break the suction seal made by the oral sucker at the smaller end of the leech, once that seal is broken, the leech cannot hold on and can be readily removed by detaching the posterior sucker)
6) that is will not hurt "because the leech has injected a numbing agent" (see my previous post about this unsubstantiated myth)

This is all timely in light of Carl Zimmer taking to task George Will and the Washington Post for failure to fact check on science. Alas, some science writers too fail to fact check. Please note that Discover Magazine where Carl is a columnist has no relationship with Discovery Communications where Brain blogs about "stuff", like medical medicinal leeches.

Injury in Iowa - Leeches score another win.

When Eric Poore looked at his finger, there wasn’t much left. Wedding ring smashed, skin, muscle and blood vessels stripped away... nothing but bare bone and the tendons holding the mangled mass together. Paramedics snipped off Eric’s gold wedding band and rushed him to the hospital. Fully four trauma centers declined to treat Poore’s poor finger until Greg Yanish rushed to fix it some hours later. Yanish describes the blood flow in a delicately reattached finger “like the drain in the bathtub is slow, but the faucet is on full blast”. Once more, leeches to the rescue! Application of several (prob. H. verbana) to the reconstructed finger both immediately and over several days and it looks like Eric Poore will get to keep his finger. (As an aside... my EMT friends remind me this is an excellent argument against titanium wedding bands... can’t be snipped off). Here's the full article from the Des Moines Register.

The Rehabilitation of Princess Caraboo

The sensational story of Princess Caraboo regards a young lady arriving in Almondsbury, England (just North of Bristol) in 1817, speaking a strange tongue and sporting various tattoos. When it was determined that she was a Princess of Javasu, kidnapped by pirates from her Indian Ocean home, she was taken in by the local dignitaries and feted for some 2 months as visiting royalty. Her scam was exposed in short order. There is no Island of Javasu. She was, in truth, one Mary Baker from Witheridge near Exeter, who, unable to find continued employment as a servant, had hit upon this rather novel method for achieving food and shelter. After being shipped off to the US by her duped, and now chastened, benefactors, the Worralls, Mary eventually returned to Bristol and by 1839 was more gainfully and respectably employed... selling leeches, of course.

Leech Barometer

The notion that leeches can predict inclement weather achieved its zenith with the creation of the Tempest Prognosticator (at left) by Yorkshireman inventor George Merryweather, and which he put on display at the first World's Fair (the Great Exhibition at London's Crystal Palace in 1851). The idea seems to trace back to the (occasionally insane) William Cowper (1731-1800) who wrote

"I have a leech in a bottle that foretells all these prodigies and convulsions of nature. Not... by articulate utterances ... but by a variety of gesticulations, which here I have not room to give an account of. Suffice it to say, that no change of weather surprises him, and that, in point of the earliest and most accurate intelligence, he is worth all the barometers in the world"

(letter to Lady Hesketh, 1789). Edward Jenner, to whom we owe the smallpox vaccine, was also an accomplished poet. In at least one (but not all) version of his Signs of Rain, the final lines read

"The leech, disturbed, is newly risen/Quite to the summit of his prison."

Merryweather cited these lines as inspiration for his Tempest Prognosticator. The device required a leech in each of 12 jars. The glass was to be transparent so that the leeches could "see each other" and so agree amongst themselves as to their prognostication. If any leech climbed up and into the escape tube, its weight would dislodge a piece of whalebone, releasing a hammer that would ring the bell thus announcing the onset of inclement weather. The Great Exhibition's jury rendered no verdict on this, imaginative, device. Nor did the Admiralty or the Board of Trade show much interest in Merryweather's storm warning system. Who needs doppler radar anyway?

Worst Science Jobs?

The February 2009 issue of Popular Science magazine has listed a suite of 2009's worst jobs in science. Among them is Leech Researcher. Amusing and well-written article by Jason Daley. I must say though... I really think I've got the best job in the world (maybe next to Carl Zimmer).

Leech Meeting in Washington DC

Friday November 14th,2008.
Waldo Schmitt Room
Natural History Museum

This event, gathering the country's leech biologists in one place, is becoming an annual affair as a premeeting to the Neurobiology meetings.

Morning session
8:45 am Welcome by Bill Moser and Otto Friesen
9:00 – 10:00 am Research talks John Hackett, moderator
Mark Siddall "Evolution of anticoagulation: Comparative salivary EST libraries from 3 leeches on 3 continents"
Eduardo Macagno "Application of MALDI imaging to study leech proteomics"
10:30 am – 12:00 pm Research talks (15’ each) Otto Friesen, moderator
Angela Wenning "News from our (leech) hearts"
John Hackett "Probing swim maintenance with drugs"
Peter Brodfuehrer "Swimming, glutamate and cell 204"
William Kristan"Leech decision-making"
Karen Mesce "Picking up the pace on what we know about the crawling motor pattern in the leech"
Afternoon Session
Posters

Leeches, Hirudin and Life Saving Dialysis

Approximately 1 in 10,000 people in Western industrialized countries relies on dialysis to replace impaired kidney function or kidney failure. The more than 300,000 Americans, and 30,000 Canadians, who have their blood cleaned of toxins and metabolic waste, can thank leeches for the invention of this life-saving treatment. Georg Haas pioneered experimental dialysis treatments on animals at the University Hospital of Internal Medicine in Geising Germany. Preventing blood from clotting in the dialysis tubes was (and still is) critical to the success of the procedure. All of Haas' early experimental work was accomplished using crude leech extracts to prevent clotting. Unfortunately, the unpurified extracts proved toxic and leeches were hard to come by in light of over-exploitation during the latter half of the 19th century. Haas suspended his experiments during WWI until he learned, from the Father of American Pharmacology, John J. Abel at Johns Hopkins in Baltimore, of the availability of purified hirudin (the anti-thrombin from Hirudo medicinalis seen at right here). Haas performed the first human dialysis treatment in 1924 using this newly available purified hirudin. Expensive, hirudin would be supplanted by the wide availability of heparin in the next 3 years. Heparin is still used in dialysis treatments. Recently, at least 80 people were killed as a result of world heparin supplies being intentionally contaminated with cheaper chondroitin sulfate. It was another 20 years after Haas' bold move before Willem Kolff invented the first dialysis machine and 20 more before Belding Scribner opened the world’s first outpatient dialysis facility at the University of Washington Medical School.

Leech Cocoons

In a series of papers, recently, Dan Shain (Rutgers University) and his colleagues have been carefully examining the structural and chemical properties of leech cocoons. As background, these cocoons are egg-cases that are secreted by the clitellum of leeches and they show some striking diversity. Brooding glossiphoniid leeches have a membraneous cocoon, erpobdellids and fish-leeches (below) cement their hardened cocoons to surfaces, and the medicinal leech cocoons (above) are pretty spongy looking. If you think about it, the material that goes into making these eggs cases must be pretty strange. First, whatever is secreted must adhere and polymerize quickly underwater and without any light or heat. Secondly, there's eveidence that leech cocoons are highly
resistant to denaturation or degredation; so much so that they seem to be showing up in Jurassic and Triassic deposits (e.g., Manum et al., 1991. Zoologica Scripta 20: 347-366; Jansson, et al. In Press, Early Jurassic leech cocoons from eastern Australia. Alcheringa). The work led by Shain has covered a variety of perspectives including the molecular composition of the proteins involved (one seems to belong to the same family as the factor Xa anticoagulants!), the structure of the cocoons and their biophysical properties.

Leeches clear a blocked carotid stent?

The Sydney Morning Herald reports that a Mehdi Jaffari (at left here) managed to clear his 80%-blocked carotid artery by self-treatment with an Australian medicinal leech, Richardsonianus australis. Mr. Jaffari had had 4 heart attacks last year, and had a stent put in his carotid, only to be told in January that he had "advanced cardiovascular damage, with his left carotid artery almost 80 per cent blocked". Five days of leech therapy and the next angiogram showed it cleared. Hmm. Regardless of the veracity of the (as yet unrepeated) claim, the article contains an untruth: "while hirudin was known to dissolve blood clots, it was not known to dissolve plaque". In fact, hirudin only prevents clots. It does not dissolve them.