Preface: Personal Parasites.................................................................ix Acknowledgments.............................................................................xi Apologia....................................................................................xiii On the Sacredness of Life...................................................................xv INTRODUCTION. The Saline Solution—An Inner Sea........................................1 1. Land of Smiles...........................................................................6 2. An Encounter with Jordan Rose............................................................15 3. I Had a Farm in Africa...................................................................25 4. Death of a Mouse.........................................................................33 5. Intimate Relationships...................................................................40 6. A Peek into the Anus of—My Child...................................................48 7. The Well-Hung Dog........................................................................58 8. Fiery Serpent............................................................................69 9. It Hardly Ever Happens...................................................................75 10. The Anti-Semitic Tapeworm...............................................................82 11. Mother Always Wanted Me to Be a Real Doctor.............................................91 12. Missus Murphy's Baby....................................................................98 13. The Day I Flunked the Macho Test........................................................109 14. The Biblical Plagues....................................................................117 15. Alley Cats and Seagulls.................................................................127 16. A Better Mousetrap......................................................................137 17. Scandals and Ghosts.....................................................................144 18. Spiny-Headed Monsters...................................................................155 19. Bloodsucking Beasts.....................................................................165 20. Ode to a Cockroach......................................................................174 21. Bats, Bugs, and Bloody Bites............................................................184 22. Little Fleas Have Littler Fleas.........................................................195 23. How to Get Rid of Crabs.................................................................203 24. Wild Virgins............................................................................211 INEXPLICABLE BEHAVIOR: Some Relationships Are More Intimate Than Others.....................221 25. Topsy-Turvy Worlds......................................................................224 26. A Day in the Caribbean..................................................................235 27. Tit, Tit, Tittie—Cuckoo...........................................................245 28. The Game of Life: Name That Category....................................................251 29. Paean of Praise.........................................................................257 30. Tips for Travelers......................................................................268 Epilogue....................................................................................277 Glossary....................................................................................281 Selected References.........................................................................293 Illustration Sources........................................................................295 Index.......................................................................................297
Standing on a street corner. Crowded, bustling. Watching a street vendor grilling what seems to be hot dogs. Hungry, I move closer— and recoil in shock. Grotesquely hanging from the edges of the bun are masses of blackened, rigid strings. Customers walk away munching with gusto, spitting out the strings as they walk. Making believe I am still hungry, I saunter up to the grill. Steam rises from charred corpses with elongate bodies and ten burnt legs. A pair of long, skinny appendages projects frontward, revealing this streetside delicacy to be the giant Malaysian prawn, Macrobrachium rosenbergii. It seems to be the Thai version of fast food.
This is Bangkok, not New York—or is it? Lined up at the stand are grungy American kids munching with some satisfaction on this exotic food, reveling in the obvious disgust of some of their brethren. The kids are part of an army of recent college graduates roaming the world, seeking the meaning of life in some other-worldly philosophy—seeking their guru in this land of saffron-robed monks. Some are pure vegetarians. These vegan vagrants are required by some inner directive to obtain their carbs as noodles from an adjacent noodle stand. The noodles are fascinating—ivory colored little balls, coils, and flat ribbons. They were plopped into boiling water for a minute, strained out steaming, and placed on a small plate. They look pale— and delicious.
Thais are, to me, distinguished by three characteristics: ubiquitous smiles, kindness, and cleanliness. The cleanliness is well intentioned but illusory. Take a water taxi up the Chao Phraya River that borders Bangkok. Houses jumble onto one another along the banks of canals called "klongs" and along the riverside. Large, amphora-like urns on each porch catch pure rain, for the river is dark with mud eroded from lumbered-over hillsides upriver, making it like thick soup. The vegetables are spoiled remnants from the markets; the meat, dead rats. Occasionally human waste punctuates the garbage-flecked surface.
Rainwater must be conserved for drinking and cooking. Children are given their daily bath with river water and scrubbed until shining—with the utterly polluted water.
The college kids on the corner go off to their dollar-a-night hostels and we go back to the Bangkok Palace to cool off and watch in-house Arnold Schwarzenegger videos—nothing else is available. In the evening we are ready for some night life. Across the street is a huge building. On its roof is a red neon sign indicating, in unintelligible Thai, its purpose. But alongside the garish sign is another, equally garish. It is a translation in neon: "fast food"—the Thai version of McDonald's. "Let's try it," I say. Wise wife points out that it is forbidden to eat regular Thai food except in the best restaurants. I insist. I go to the counter, behind which is a smiling woman. I point to a plate of particularly inviting flat noodles. I say, "What harm can noodles cause?" Wise wife says, "They will kill you."
The smiling woman picks up the plate of noodles. I reach for it. She turns around and places the plate into a grimy hand that miraculously extends from a black hole in the wall. "See, the noodles are going to be boiled," I say uncertainly. After a moment the woman hands me the newly heated plate. I cough up a few baht (cents) in payment and sit down at a table. Wise wife repeats, "They will kill you." I repeat, "The noodles are boiled." I swallow a noodle, noting that it is lukewarm.
Two days later, doubled over in pain, I alternate copious diarrhea with uncontrollable coughing. I think, "This cough is symptomatic of a bacterial infection," and we continue our trip. I almost fall off an elephant in the North. Later on, in Egypt, I am too weak to explore the magnificent temple at Karnak. We reach Israel. Wise wife insists that I bring a fecal sample to the "American Clinic" (distinguished from the others only by the fact that they charge American prices). I am at work. The physician calls. He says that I have "many, many, many amebas" in my intestines—amebic dysentery!
Those rotten American kids eat their way through Thailand and remain healthy. I eat one plate of noodles and get dysentery.
KILLERS IN THE GUT
The cause of amebic dysentery is the one-celled, amorphous protozoan called Entamoeba histolytica (histo = tissue, lytica = to dissolve). It really dissolves tissues, digesting its way through the walls of the intestines, in the process greatly irritating them. This stimulus produces a massive outflow of neuronal activity that the brain converts into return messages increasing the motility of the intestines. The contents of the gut move so fast that the colon cannot absorb enough water from the feces, resulting in diarrhea.
Death from diarrhea-induced dehydration is the primary cause of infant mortality in the world. Frequently the diarrhea is caused by E. hystolytica. When in diarrheic (liquid) feces, the amebas take their usual form—or their usual nonform. Amebas are shapeless, single-celled organisms. Bulges appear and disappear with no apparent pattern. When a food particle touches the cell membrane, it is surrounded by these bulges (pseudopodia). Presto! The food is inside the animal and being deluged with enzymes. Digestion occurs. During this feeding phase, called the trophozoite, each ameba is able to reproduce by splitting in half, becoming two—part of a reproductive strategy that will eventually create a veritable invading army. Due to its amorphous shape, E. histolytica is not easily diagnosed. One criterion for differentiating this pathogenic species from other (harmless) intestinal amebas is whether or not a dot in the nucleus is centrally located or off center. Diagnosis is therefore difficult, though crucial. One must go through a regimen of possibly toxic medications if the dot is central, but if it is askew, the ameba is harmless and no medication is needed. Quite a responsibility for the technician half asphyxiated from the smell of the material under the microscope.
Entamoeba histolytica enters the body in contaminated water or food containing cysts that are resistant to the acids of the gastric juice. Normally, this very acidic fluid, secreted by the walls of the stomach, acts as a fluid gate, preventing the entrance of harmful organisms by killing them with acid (which will eat away a penny in a day). But some protozoan parasites produce plasticlike "shells," microscopic spheres called cysts, that resemble minute eggs. The impervious cysts pass through the gastric gate, entering the small intestine. They flow through the richly inviting small intestine, waiting until they reach the environs of the large intestine (colon or bowel) to escape their imprisoning capsules—but not before reproducing again, splitting into four or eight amoebulas. This massive geometric progression produces the inner army that is destined to do the damage.
The immature amebas escape from their protective prison and begin to feed on the copious food surrounding them. What causes an ameba to forsake its fetid paradise and invade the walls of the large intestine is unknown, but ameba genetics and host food habits are involved. Some human populations are particularly vulnerable. An epidemic in Durban in the 1930s killed thousands of black South Africans while hardly harming the white population. The diet of the poor, rich in carbohydrates, has been shown to stimulate the invasive mode of feeding. In theory, adequate protein in a human diet will satisfy the needs of the parasite. Or is it that protein-poor diets lead to malnourishment and the concomitant vulnerability to penetration of the gut wall? Or is it the host's genetic vulnerability to the pathogen?
INVASION OF THE CLONES
When an invading colony is established, it digests its way through the inner surface layer (mucosa) of the intestinal wall, becoming an army by splitting into an overwhelming number of clones. These legions enter the blood-vessel-rich submucosa. Like Roman armies, some sail off in the blood to establish outlying colonies elsewhere, primarily in the liver, sometimes causing fatal hepatitis. The rest of the legion digests its way through the submucosa and reaches the tough, muscular middle layers of the intestine wall. They are slowed but not stopped. In cross section the lesion looks like a microscopic mushroom as the frustrated amebas spread out under the seemingly impregnable muscle layer. Finally a narrow tunnel is drilled through, allowing the invaders to penetrate through the outer layer of the gut and burst out into the peritoneal cavity in a foul mixture of intestinal bacteria, feces, and amebas—often causing fatal peritonitis.
But in most cases the amebas remain in the colon and are carried along by the slowly flowing peristaltic river of intestinal contents. They confront obstacles and eddies where the flow is reduced. There the amebas establish their colonies. The cecum, a blind sac near the entry point of the small intestine into the large (from which the appendix protrudes), is one such vulnerable sluggish spot.
One can map the high-risk regions based on the flow rate. The sigmoid flexure, the S-shaped convolution before the rectum, is another area of colonization. Once the amebas reach the end of the "river" and pass out of the anus they are still dangerous. They may invade from the outside, producing surface colonies that penetrate the skin around the anus, then float off in the blood. Any organ in the body can be infected by migrating amebas in the blood: the eyes, the brain, the lungs, the liver.
During the first half of the twentieth century, few medications were available to cure intestinal protozoan infections. Traditional choices were similar to cleaning fluid—on the theory that the poison would kill the tiny parasites before they killed the bigger host. Then a new drug was developed to kill flagellated parasitic protozoans infecting horses and cattle (there is a very profitable market for veterinary medicines). Incidentally, it was found effective against a variety of human parasites.
The horse medicine worked. In a few days my symptoms disappeared.
FROM OOZE TO INTESTINES
Once upon a time, amebas oozed their aimless paths through the mud of a pond. The seasons inexorably brought their changes. Spring became summer and the heat of the sun warmed the water. Warm water evaporates. The pond began to shrink and became a pool, then a puddle. Stressed by summer's changes, things died and rotted. Levels of ammonia associated with rot increased. Bacteria gorged themselves on the dead, reproduced massively, and used up most of the oxygen.
The pool continued to shrink; conditions became unbearable. Finally a smelly, muddy stain remained where the pond used to be. All its inhabitants died—or adapted to this most stressful of all environments. The most challenging stressor to overcome was dryness—to survive in the period of parched mud and wait out the drought until the rains came.
Over eons the amebas changed. Some evolved "shells"—microscopic invulnerable spheres called cysts that remained in the muddy bottom until autumn's reprieve. The rains returned and the pond revivified. Inside the cysts life stirred. But the amebas could not escape their self-imposed prisons. They had survived the dryness only to die in their newly evolved cysts in a futile evolutionary experiment. More almost limitless time passed. Finally, responding to signals in the water, a new kind of ameba cracked open its cyst and a new generation escaped into the all-providing mud.
What does this story tell? It seems to describe the evolution of pond-dwelling amebas. But there is a hidden meaning. Conditions in the drying pond very closely resemble the contents of the human intestine: high levels of ammonia and methane, low oxygen concentration; crowds of bacteria thriving at warm temperatures; the massive presence of organic matter.
But hell lies in the way to paradise: the burning cauldron of the pit of the stomach, its core so acidic as to kill all who pass that way. The amebas are thwarted. But some species had evolved the safety of cysts. They could pass through the acidic fires of hell unscathed. The same kinds of signals that saved them in the pond saved them here. They passed through the stomach and excysted in the pondlike conditions on the other side, the intestine.
This phenomenon, called preadaptation, seems fanciful, but living models make it real. Two harmless genera of ameba, Vahlkampfia and Sappinia, live in sewage. They are able to encyst. Bad little boys swim in the effluent of sewage disposal plants. Laughing and splashing, they ingest the water and cysts. Still skeptical?
Tel Aviv, Israel, 1968. The two-year mission at Tel Aviv University loomed ahead. We were "strangers in a strange land." This was the exotic Middle East. We were fearful and uncomfortable in this foreign place. The university assigned a person to help us find housing. He drove us through the surrounding communities. They looked unfamiliar. We felt disconnected.
Suddenly, America appeared. Down a street that ended in sand dunes, we saw a little bit of home. A small house surrounded by a neat lawn. Bougainvillea covered one wall in bright orange flame. Profusely blooming pink-purple oleander hedges bordered the property. "That's it," the kids cried.
It remained to make the rental arrangements. Our guide took me to the lawyer's office. Idly glancing around, he said, "This lawyer is from Iraq." "How can you tell?" I asked.
"Look at the clients' faces." I looked for some sign of their national origin. There were about ten people waiting their turn. I saw no obvious similarities. Nose shapes varied, hair color varied, and faces were typical of the kaleidoscope of physical traits common in this polyglot nation. What was the distinguishing feature? I looked closer. Nothing. Then he whispered in my ear. "Look at their skin." I didn't see any tattoos, pimples, or patterns of pigmented beauty marks. Still nothing. Suddenly it hit me—they all had a flowerlike scar on their faces.
He explained, "People get an insect bite. It turns into a pimple just like a mosquito bite. The pimple spreads and becomes a big sore that rots and becomes infected. Then you have to go to the hospital. Adults can get bad symptoms, and their faces can be scarred like these people. If you get infected when you are young, the sore isn't as bad. You can't get the sore again. My family knew this and we put our children outside on warm nights to get bitten. We covered their faces to let the bugs bite in an inconspicuous place, like the legs. You can see that I don't have a scar on my face."
He raised one of his trouser legs. A fist-sized, flowerlike scar was revealed. I thought, "This is the mother of all mosquito bites." Then the epiphany. I dredged up long-past memories of a disfiguring parasitic disease caused by a flagellated protozoan, Leishmania tropica. The condition is mildly pathological, with few symptoms other than an enlarged vaccination-like scar. It is so common in the Middle East that it has many names: Jordan Rose, Jericho boil, and Aleppo boil. Clinically it is known as cutaneous leishmaniasis.
An affair with Jordan Rose is relatively benign—a one-night stand with her causes a lifelong scar. But it is her sisters that you don't want to associate with. The other species of Leishmania cause horrible pathological symptoms, often ending in death.
FEMME FATALE
The vectors of leishmania are sand flies of the genus Phlebotomus that look like hairy mosquitoes. Unlike most mosquitoes, sand flies can make do with moist, rotting garbage and piles of stinking organic debris for breeding. Mosquitoes cannot survive in the intense heat of dry Middle East desertlike environments, but sand flies hide in slightly moist cracks and crevices of mud and stucco walls in the daytime and, revived by the night's cool breezes, fly off into the darkness to suck the blood of any available host: gerbil, rat, cat, dog—or human. This lack of particularity maintains a reservoir of infected blood. Even if a drug is developed to eradicate the disease and few infected humans are available for the fly to feed on, rodents and domestic animals become reservoir hosts. Inside their sick bodies the infective first stage of the parasite's life cycle malevolently waits for life-sustaining passage into a fly's body in which develop hordes of slender, undulating procreative needles.
(Continues...)
Excerpted from WHAT'S Eating YOU? by EUGENE H. KAPLAN Copyright © 2010 by Eugene H. Kaplan. Excerpted by permission of PRINCETON UNIVERSITY PRESS. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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