Parasite Rex: Inside the Bizarre World of Nature's Most… (2024)

This book is disgusting almost beyond words. For instance there are 5,000 species of tape worm, and the one we associate with human beings can grow inside us, in our intestines, to be 60 feet long. And that is just the beginning of the disgustingness! Ewwwwww!

On the other hand the book is utterly fascinating, and it illustrates with stunning clarity some of the endless conceits and machinations of nature. I am tempted to say "intelligence" of nature, because this level complexity and dove-tailing of species seems almost too miraculous to have happened on its own, but this is just Darwinian jiggery pokery at its best.

Zimmer is an excellent writer too, and most of the book is hugely readable. I don't think it gets off to a good start though, it seemed a bit scatty and all-over-the place to begin with, but hang in there, as rest of it is brilliant. Highly, highly recommended.

Herewith some photographs illustrating parasite horribleness.

Hookworms live inside 1.3 billion people. They use their powerful teeth to lacerate a patch of the intestinal wall and drink blood from the wound.

Parasites often choose very particular – and peculiar – places to live. This crustacean invades a fish’s mouth, devours its tongue, and takes the tongue’s place. It then acts like a tongue; the fish can use it to grip and swallow prey.

Once a parasite has used up its host, in needs to escape . Herewith a fungus emerging from an ant.

Another exit...here a worm-like parasite called a nematomorph escapes its cricket host.

And herewith some (fairly copious) notes I have taken for my own interest; mostly just verbatim extracts from the book. Common parasites:

Trypanosoma bruceigambiense – causes sleeping sickness

Onchocerca Volvulus – causes scratching to the point it can be fatal, or blindness (known as river blindness).

Tambura guinea worms- two foot long creatures that escape their (human) host by punching a blister through the leg and crawling out in the course of a few days.

Filarial worms – Cause elephantitus, which can make a scrotum swell up until it can fill a wheelbarrow. The can also create monstrously swollen legs or breasts. 120 million people are infected with filarial worms.

Taenia solium - Tapeworms - These are a parasitic animal. They usually come to humans via pigs. They can be harmless or fatal, depending upon where they settle, e.g., they can cause inflammation of the brain and trigger epileptic seizures if they settles there. The can cause death, by the immune system trying to fight off such a huge target.

Blood flukes – These are unusual in that they manage to flourish in the vast majority of their hosts whilst only causing them very little trouble. 200 million people have schistosmiasis, the disease caused by blood flukes.

Acaris Lumbric Oides (roundworm) 1.4 billion people carry this in their intestines

Whipworm – 1 billion people carry this

Hookworm – 1.3 billion people carry this

Trypanosome – 20 million people have this. It causes Chagas Disease. This is a parasite with a limited geography.

Plasmodium – This causes malaria

Leishmania Brasiliensis – Causes epundia – the parasite chews away at the soft tissue of the head until its victim is faceless.

Toxoplasma – this is associated with cats and rats. Perhaps the most common parasite on earth. Many people have it but their immune systems keep it in check. It affects people with low immune systems – eg babies inside their mothers’ wombs, and people with HIV/AIDS. In 1990 an expensive drug was brought onto the market which helped AIDS sufferers – but many cannot afford it. The end of this disease is very unpleasant.

One sign of the sophistication of these parasites – the protozoa, flukes, tapeworms and other eukaryotes – is the fact there is no vaccine for them, while there are many vaccines for viruses and bacteria.

The tapeworm that lives in stingrays in the Amazon show how the river once flowed backward. They are more closely related to tapeworms living in the Pacific than in the Atlantic ocean.

These are shelters for insect parasites. Hundreds of different insect species live in galls. They can form on flowers, twigs, stems or leaves. The galls are formed by the plants themselves, yet they are the work of the parasites

Darwin suffered in most of his adult life with fatigue, dizzy spealls, vomiting and heart trouble. Some have suggested he had Chagas disease. This is caused by Trypanosoma Cruzi, closely related to to Trypanosoma Brucei, the cause of sleeping sickness. T. Cruzi slowly wrecks parts of the nervous system. It is spread by the Benchuca, a biting insect of South America, and Darwin was bitten by one as he was travelling the world on the HMS Beagle.

It may be that parasites were the cause of sex in mammals. In the primordial soup things that wanted to reproduce simply divided themselves in half. Even today, bacteria simply divide themselves, as do many single-celled eukaryotes. Many plants and animals have the ability to reproduce themselves quite comfortably alone.

Several biologists, including the Oxford University biologist William Hamilton have argued that when hosts are faced with parasites, sex can be a better strategy for fighting them than cloning. With sex, the genes get shuffled around, which makes it much harder for parasites to chase their hosts e.g., if amoebae reproduce sexually they no longer come in distinct strains, and it becomes harder for the parasites to get a lock on them. It is also seen clearly in bees, as demonstrated by Paul Schmid-Hempel, a Swiss biologist. The offspring of queen bees with high diversity DNA are much more powerful against parasites than those with low diversity DNA.

We often think of cats as ultra-clean animals, in fact they are grooming to remove parasites. When we see gazelles grooming themselves this is not in response to any particular scratch, rather they clean themselves according to a clock-like schedule because parasites are so relentless. Grooming cuts into the time an animal needs to eat and guard against attacks from predators. The top impala of a herd for instance ends up being riddled with ticks. Six times more than the females – because he is too busy staying vigilant against male challengers to groom himself for parasites.

Some of the parasites that attack mammals include lice, fleas, ticks, botflies, screwworms and warbleflies.

Leaf-rolling caterpillars for instance attract parasites via the odour of their droppings. They therefore project their droppings like missiles, and they land 2 feet away from the caterpillar.

Some researchers have suggested that mammals that make long migrations, such as caribou and wildebeest, plot their course in part to avoid parasite-thick spots along the route.

The antibody we all carry as mammals which helps us fight parasites is immunoglobulin E(IgE). IgE is rare in the USA and the few other parts of the world that are now free of intestinal worms, blood flukes and the like – but the rest of humanity (plus other mammals of course) carry a heavy load of flukes, worms and IgE.

1 in 400 African Americans have it. It usually kills people by the time they are 30. The only reason this sometimes defective beta chain gene stays in such high circulation is that it’s a defence against malaria. Other disorders that are the result of the body trying to fight off malaria – ovalocytosis and thalassemia.

1) They happen to the poorest people in the poorest countries.

2) Many of these parasites aren’t fatal, but the effects of chronic infestations with parasites are still devastating – leaving people listless and undernourished. Parasites like hookworm and whipworm make it hard for children to learn in school; all it takes is a dose of anti-whipworm medicine to make some slow children bright again.

There used to be malaria in the US, and many people in the south were affected with hookworm. 25% of pork used to carry Trichinella in the 1930s.

But all of that has changed. The US no longer has to be worried about these parasites, but not because anyone invented a magic bullet. Instead they’ve been overwhelmed by the slow, dogged work of public health campaigns, of building outhouses, of inspecting food, of treating infections to break the cycles that parasites had taken for thousands of generations before.

Guinea worm.
This was stopped in Pakistan altogether in 1993, and numbers are falling elsewhere. It’s conceivable that in a few years it will be wiped out.

Onchocerca volvulus (the worm that causes river blindness)
This has a partial cure with the drug Ivermectin, which kills the baby worms – the ones that do the most damage. The pharmalogical colossus Merk has donated as much Ivermectin as will be necessary to cure the world of river blindness.

Filiarial worms (the worm that causes elephantiasis).
It has recently been found that Ivermectin also works against filiarial worms.

Eradicating parasites may create new diseases. There was no record of Crohn’s Disease or Colitis in the US before the 1930s. In poorer countries these diseases are virtually unheard of. In Japan and Korea – two countries that have gone from poverty to wealth quickly – there are now epidemics of Crohn’s Disease and Colitis. Some scientists think the spread of these diseases was caused by the eradication of intestinal worms. Even farm animals are starting to get bowl diseases since being treated with anti-worm medicines like Ivermectin.

Parasitologists have found that intestinal worms can nudge the immune system from a poison-sprouting, cell-engulfing frenzy to a gentler sort of attack. In this mellower mood, the immune system can still keep bacteria and viruses in check, but the parasitic worms live unmolested. This arrangements benefits the host (the human) well. When parasitic worms are abundant it would be dangerous to attack them over and over again. But then, in an evolutionary blink, a few hundred million people lost their parasites. Without their soothing influence, some people now swing too far the other way, their immune systems unable to stop attacking their own bodies.

In 1997 scientists at the University of Iowa put this idea into startling practice. They picked out 7 people with Ulcerative colitis and Crohn’s Disease who had got no relief from conventional treatments. They fed them eggs from an intestinal worm that wouldn’t cause any disease of its own in a human gut. Within a couple of weeks the eggs had hatched, the larvae had grown, and 6 out of the 7 people went into complete remission.

(Note: and here is a current update on the use of parasites with these diseases....

http://en.wikipedia.org/wiki/Helminth...)

Crohn’s Disease and Colitis are not the only problems caused by a lack of parasites. Allergies may well be another issue. 20% of the population in industrialized countries suffer from allergies….but elsewhere they are hard to find. Neil Lynch did a study in Venezuala.

People from upper class homes with running water and toilets:
43% had allerties – only 10% of these people had a light infection from
Intestinal worms.

Poor peole:
22% had allergies. 20% had an infestation of intestinal worms.

Indians who lived in the rainforest:
None of them had allergies. 88% were infested with parasites.

Without parasitic worms exerting their influence over our immune system, it may be prone to overreacting to things like harmless bits of cat dander and mould.

Perhaps some day, along with polio vaccines children will get parasite proteins, so their immune systems will be trained not to fly out of control.

Parasites can be used to control crop pests e.g., cassava, a staple crop feeding many people in Africa, was affected by a virulent strain of mealybug. In 1979 this was studied by the Swiss scientist Hans Herren, an entomologist. Eventually he tracked down a parasitic wasp in Paraguay, able to attack these mealybugs. They were dropped from aeroplanes over affected areas. The operation cost $30 million, but about 200 million people were at risk from losing their staple food crop, and this was avoided.

But parasites introduced into new habitats can cause disasters e.g., the forests of Hawaii are filled with alien parasites brought in to destroy insect pests; but they have also affected the moths that birds eat, so the bird population of Hawaii is declining.

(Note: of course it has become popular nowadays to use parasites in our gardens....

http://groworganic.com/organic-garden...)

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The photographs were copied from the book.

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