The Germ of Laziness



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The Germ of Laziness

  • Up until now, we’ve mainly focused on bacteria and viruses, but there are many other microscopic creatures that affect our lives in important ways

  • Like the lowly nematode worm…

  • Most nematodes are extremely small, on the order of 2.5 millimeters or smaller, about a tenth of an inch

  • Many species, like the hookworm and the Trichinella worm, are barely visible to the naked eye…

  • Nematode worms, also called roundworms, are one of the most abundant, most diverse, and least understood creatures on this planet

  • Few people have even heard of nematodes, but the 28,000 species we have already named may only be a tiny fraction of the one million species waiting to be discovered…

  • Nematodes are incredibly abundant

  • A typical shovel full of garden soil may hold over a million worms

  • A single acre of farmland might shelter a billion!

  • 90% of the life on the ocean floor consists of different species of nematode worms…

  • It’s hard for us to fathom the extent to which our world is defined by nematodes, in the most literal sense of that word

  • N.A. Cobb, one of the world’s foremost nematologists, wrote a haunting description of nematodes...


  • When you first see a nematode worm under the microscope, they look like they’re on their fourth cup of coffee

  • Their tiny snake-like bodies constantly curl and thrash around aimlessly

  • Nematodes don’t seem to be going anywhere in particular

  • But when we look at them under the microscope, we’re not seeing them as they really are

  • It’s like dropping a kitten into a big jar filled with water, and judging its frantic scrambling to get out to be the normal locomotion of kittens (and please, don’t try this at home!)

  • If we could get small, and join the nematodes in their natural habitat, all of that thrashing about would suddenly make a great deal of sense…

  • Nematodes live in a world we never see, although we walk over it every day, the interstitial habitat, the spaces in between

  • The story of nematodes is the story of life between the cracks

  • We think of dirt as something solid, but on a microscopic scale, it’s riddled with tiny irregular spaces, as all the various fragments of mineral soil, dead vegetation, bits of bugs and other natural materials, are jumbled together to form what we call soil

  • In this complex, three-dimensional realm, what appears to be aimless thrashing under the microscope, becomes an exquisite adaptation (peristalsis)

  • Nematodes, however, lack circular muscles - whip-like curling and writhing results from the alternate contraction of longitudinal muscles on either side of their body

  • It’s the perfect motion for wriggling through a complex maze of tiny irregular spaces

  • And nematodes do a great deal of wriggling

  • They’re so abundant that their constant movement through the soil helps plants to grow in it

  • If it weren’t for nematodes, soil would be much more compact and solid

  • Nematodes and earthworms keep soil loose and open, letting water and air into the dirt, and easing the passage of roots

  • Ironically, many species are also root parasites, causing several billion dollars in crop damage every year

  • They’re very simple animals, with a tough outer cuticle that keeps them from being worn away as they push through the soil

  • Some have circular bands or ridges to grip the dirt

  • Males are usually smaller than females, and have a tiny copulatory hook they use in mating

  • Many are carnivorous, eating a variety of tiny creatures, algae, and dead things

  • But about 16,000 species are parasites, like the nematodes that cause heartworm in dogs and cats

  • As soon as our ancestors descended from the trees and set foot upon the soil, they were exposed to teaming hordes of parasitic worms

  • We evolved one type of antibody, IgE, specifically to deal with parasitic worms

  • We suffer from many terrible nematode diseases

  • Elephantiasis, for example, is caused by worms blocking the circulation of the lymphatic system, an important part of the immune system

  • Ascaris, the intestinal roundworm, is another nasty nematode parasite

  • It’s very common in young vertebrates, especially young children in the southeastern United States, where playing in the dirt is a year-round affair

  • Ascaris gets to be a foot long or more!

  • One out of six people worldwide are infected

  • The female worm can hold up to 1 million eggs, and can lay up to 200,000 eggs per day!

  • Every year, on average, 340 million Ascaris victims experience serious side effects, with 100,000 deaths

  • Trichinella is the nematode that causes trichinosis in birds and mammals

  • The worms form cysts in the muscles of pigs, and we get the worms when we eat undercooked pork

  • Permanent organ and muscle damage often results, as up to 500 million worms tunnel through the body

  • Trichinosis used to be much more common than it is today

  • Thanks to a combination of government oversight and public awareness, trichinosis is now rare in the developed world

  • There are only about twelve cases every year in the United States

  • But one nematode stands out from the rest, a microscopic worm that caused millions of people to be labeled ignorant, lazy, and shiftless

  • They called it the germ of laziness…

  • Or that’s what it was dubbed by the New York Sun, to the chagrin of the stalwart young doctor who discovered it, Charles Wardell Stiles

  • Stiles named it Necator americanus, the American killer…

  • It wasn’t a germ, as Stiles had explained to the reporter, but a worm, a type of nematode called a hookworm, after the tiny fang-like hooks it uses to attach to the intestinal wall

  • Every time I look at a hookworm, I’m reminded of the giant sandworms that inhabit Frank Herbert’s fictional world of Dune

  • Hookworms are extremely common, and globally distributed

  • Between 570 and 740 million people are currently infected with hookworms, about 10% of the Earth’s population!

  • They’re very small, a mere 7 to 10 millimeters, about a quarter of an inch

  • For many victims, the worms are more annoying than life-threatening, one more tiny passenger looking for a free lunch

  • We can even pick up stray hookworms from dogs and cats, a condition known as cutaneous larvae migrans

  • But these accidental invaders can’t get all the way through our skin, and can only tunnel back and forth within it (which is bad enough!)

  • Hookworms are an ancient problem - symptoms are described in a 1500 BC Egyptian papyrus, and by the great Persian physician Avicenna, in the 11th Century

  • There are two species of hookworms that infect humans, the Old World Ancylostoma duodenale, and the New World Necator americanus

  • 95% of the worms in the American South are Necator americanus, which probably arrived with the slave trade

  • It’s found throughout the tropics, in the Southwest Pacific, in Africa, and throughout Asia

  • The female hookworm lays up to 30,000 eggs a day, as many as 54 million in her lifetime, and deposits them directly in our intestine

  • The eggs are shed in feces, and if those feces are deposited on warm loam or sandy soil, the eggs soon hatch into larvae


  • The young worms can live in the soil for several weeks, patiently awaiting an errant footstep

  • When a bare foot rests on the soil, the worm quickly scrambles aboard, and burrows into the skin

  • Now, most people who spend their lives in bare feet have built up formidable calluses

  • But this clever invader instinctively goes for the one place most vulnerable on everybody’s feet, the tender skin between the toes…

  • Once in the body, hookworms migrate through the blood to the lungs, and up into the throat

  • I hate to tell you this, but your Mom might have misled you (sorry to blow the whistle, mom)

  • Swallowing your phlegm is actually a much better idea than coughing it out

  • Rather than releasing all those microbes to infect others, you consign them to an early grave, as they fall into the pit of stomach acid that awaits them – hey, they deserved it!

  • But that is precisely what the hookworm is counting on!

  • It’s an express-train ride directly to its ultimate destination – your intestine, where it will live for up to five years

  • When it arrives in the small intestine, it attaches itself to the intestinal lining, and feeds on your blood

  • No wonder some people called it the “vampire of the South”

  • Hookworms can also be passed to babies in mother’s milk, and many Asian babies die from such infections every year

  • In developing countries, up to one-third of pregnant mothers have hookworms, and about 20% of maternal deaths are associated with anemia

  • The actual death rate from hookworm worldwide is low, however, about five thousandths of a percent (0.005%) of its victims

  • But that’s little compensation for its victims, for whom it creates a kind of living death…

  • Victims of hookworms become pale, and anemic, and suffer severe digestive problems

  • Their muscles become weak, and their abdomen may protrude (potbelly)

  • They get unusual dietary cravings (pica) – they eat chalk, and paper, and dirt – hence the reputation of southerners as dirt-eaters

  • They become so frail, their protruding shoulder bones are sometimes called angel wings

  • Severe infection can also retard growth, and leave hookworm victims shrunken and malformed

  • Hookworm victims appear gaunt and haggard, with a sallow complexion often described as a thin, waxy translucent layer, over a darker saffron

  • Marion Carter, in a 1909 article in McClure’s Magazine describes them as:

  • “Feeble, slow-moving creatures, you recognize them at once by their lusterless eye and a peculiar pallor – the Florida complexion…If you speak to one of the saffron-hued natives…you are generally met by a very curious fish-eyed stare, without a gleam of intelligence back of it.”

  • The poor condition of southern soldiers due to chronic hookworm infection may have contributed to the outcome of the Civil War

  • Large numbers of southerners gathered in unsanitary camps, defecating outdoors, most of them barefoot due to a chronic shortage of shoes - a recipe for massive infection


  • Robert Penn Warren accurately describes rebel soldiers as “those gaunt, barefoot, whiskery scarecrows”

  • Hookworm symptoms are many and varied

  • The only initial symptom might be a mild rash on the feet or lower legs, known in the South as “ground itch”

  • It can take 5 to 7 weeks for the worms to fully develop, mate, and start laying eggs

  • Finding eggs in the feces is the only reliable diagnostic test in the early stages of the disease

  • And that poses a big problem for its millions of victims…

  • The symptoms are so general, and could be due to so many other health and nutritional problems, that hookworm is difficult to diagnose, especially in the early stages

  • Most victims appear to be asymptomatic

  • But the damage done by these blood-sucking worms is subtle and insidious

  • It’s a silent and steady drain on the body’s resources, and if untreated it can be debilitating, even life-threatening

  • Chronic infection dulls the mental and cognitive processes

  • It also leaves victims easily fatigued - hence the name “germ of laziness”

  • Soils, climate, and primitive sanitary conditions provided a nearly perfect breeding ground for hookworms in the old South

  • Throw in bare feet, little medical care, and few public health programs, and you have all the ingredients for an epidemic

  • At its peak in the late 19th and early 20th Century, hookworm infected about 40% of all southerners, primarily in poor rural areas

  • But this widespread infection and suffering was virtually unrecognized

  • It took a young crusader with an evangelical bent to discover the true extent of the problem, and dedicate himself to solving it, a young man named Charles Wardell Stiles…

  • Stiles was the son and grandson of strict New England Methodist ministers

  • As a precocious young boy, he was given three choices for spending the rest of the day after church on Sunday


  • He could walk in the graveyard, and contemplate his mortality…

  • He could spend it singing hymns…

  • Or he could spend it reading the Bible

  • Stiles opted for the first two, but soon grew bored and turned to the Bible


  • It didn’t take long before that became a chore as well, so to challenge himself he got a French Bible, and set about translating it into English

  • He went on to translate parts of it from Latin, Greek, German, and Italian

  • He was enthralled by nature - his bedroom and pockets were a rotating museum of natural curiosities

  • But he chafed against his strict upbringing, and was always in trouble

  • As a boy, he ruined his mother’s favorite kettle, boiling down a cat skeleton in the kitchen while his parents were away, and wandering off to play ball…

  • He didn’t even worry about it, until he happened to look back in the middle of the ball game to see black clouds of smoke billowing out the kitchen window


  • In high school, says Stiles, he majored in “deviltry, athletics, and military drill”

  • When Stiles nearly died of pneumonia, his high school principal reassured his parents that Stiles wouldn’t die of pneumonia, he was born to be hanged!


  • At Wesleyan College, he strung the laundered petticoats of the President’s several daughters from the steeple of the university chapel one Sunday morning!

  • But the rebellious teen grew into a dedicated and hard-working young man, who studied in Berlin and Leipzig, and went on to a post-doctorate at the Pasteur Institute

  • Stiles had seen hookworm in Germany, and encountered it again in Texas in 1902, while working for the US Department of Agriculture

  • The Texas hookworm, however, turned out to be a distinctly different species from the Old World variety, and Stiles named it Necator americanus, the American killer

  • After describing the new species, he toured the South looking for hookworm, and to his surprise, he found it everywhere

  • He became determined to do something about the problem, and he turned to John D. Rockefeller for help

  • Rockefeller agreed to donate one million dollars to fund a five-year study called the Rockefeller Sanitary Commission for the Eradication of Hookworm Disease

  • The RSC was an odd mixture of science, politics, economics, and evangelism

  • Early evidence from RSC health inspectors supported Stiles’ predictions, finding infection rates ranging from 40% to 82%

  • In some rural schools, every single child was infected

  • Fortunately, hookworm is very easy to cure

  • Thymol, an extract from the Thyme plant, was effective, and widely used until the 1920’s

  • But Stiles found it very difficult to eradicate hookworm…

  • Although hookworm is easy to cure, it is also very easy to become re-infected

  • You have to stop going barefoot, and stop defecating outdoors, two habits Southerners were loath to part with!

  • In fact, many thought the RSC was a conspiracy to sell shoes, while Rockefeller secretly bought up all the shoe factories!

  • Indoor plumbing was rare in rural areas, even outhouses were few and far between

  • 80% of southern rural schools and churches lacked a privy, and they were even scarcer in country farms and homes

  • Changing people’s toilet habits was very difficult, partly because the entire subject of privies and excrement was taboo, especially in mixed company

  • Stiles was sometimes threatened with violence while trying to interview victims, or when asking for stool samples

  • Even the editors of the Rockefeller Commission reports were offended, and asked Stiles to remove the section on privies as “exceedingly undignified, even disgusting”

  • Mistrust often undermined his initial efforts to train public health officials, local doctors, and school children


  • Stiles was mistrusted by medical doctors because he was a zoologist

  • And he was mistrusted by local public health officials and citizens because he was a carpetbagger, one more damned Yankee with an agenda

  • Southerners took great offense…

  • “Where was this hookworm or lazy disease when it took five Yankee soldiers to whip one southerner?” asked the Macon Telegraph

  • By the end of the study, however, Stiles had won over all but his harshest critics, with his relentless barnstorming and evangelical zeal

  • African-Americans were more resistant to hookworm, maybe due to long ancestral exposure to hookworm in Africa before slavery

  • Some slaves were probably healthier than their overseers, a rather subtle form of evolutionary revenge!

  • Hookworms provided a tailor-made solution to a difficult socioeconomic problem - what to do about the South?

  • The South lagged far behind the North, with most of its rural population, both black and white, trapped in the snares of a feudal system of sharecropping

  • There was no reliable working class to provide a solid basis for industry

  • Many southerners were undernourished, and in poor health, and the South had such a bad reputation for dirt and disease that northern insurance companies even charged higher rates to their southern customers!

  • The RSC campaign provided a way for northern capital to create a much healthier and smarter southern working class, to feed the textile mills and other industries

  • The mobile dispensaries that provided free hookworm cures were modeled along the lines of religious revival tents, and did a lot to persuade poor rural citizens to cooperate with local and federal health officials

  • Once this link was established, the state continued to encourage and enforce it

  • Historians continue to argue whether the motives of the RSC were economical or evangelical

  • As George Vincent, President of the Rockefeller Foundation, said in 1918, “For purposes of placating primitive and suspicious peoples, medicine has some decided advantages over machine guns.”


  • But regardless of motivation, the RSC left in its wake not only healthier citizens, but a greatly enriched state and local infrastructure in medicine and public health

  • One of the most important consequences was regular health examination and treatment of school children

  • School attendance and performance also increased, as did agricultural productivity

  • A happy ending to a sad story!

  • And speaking of happy endings…

  • New vaccine enters clinical trials in Africa in 2014

  • Took over 30 years to develop!

  • Goes after two key enzymes in hookworm metabolism, slowly kills it


  • In what may be the oddest twist of fate, swallowing hookworms has recently been proposed as an experimental cure for asthma…

  • It isn’t the first time we’ve been down that road – tapeworms were actually once sold as a diet plan!

  • The idea is to use small doses of hookworms to suppress an over-reactive immune system

  • Asthma is an extreme over reaction of the immune system to common substances

  • Hookworms make immunosuppressants, substances that can inhibit the immune system

  • For the asthma victim, it could be like dumping a pail of water on a small fire before it gets out of control

  • Unfortunately, researchers at the University of Nottingham were unable to demonstrate any therapeutic effects in recent clinical trials

  • Nevertheless, many scientists continue to explore hookworm therapy as a treatment for asthma, ulcerative colitis, Crohn’s disease, and even multiple sclerosis

  • And so a microscopic worm helped create the stereotype of southerners as ignorant and lazy hillbillies, and may contributed to the outcome of the Civil War

  • And the war waged against it, by Charles Wardell Stiles and the RSC, helped to create the New South

  • But not every tale of our never-ending war against harmful microbes has a happy ending - as we’ll learn in our next lecture, when we confront the deadliest killer of all time, the virus that caused the 1918 Flu



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