Parasite Rex by Carl Zimmer

This book is a close up look into the parasitic world. Carl Zimmer takes us into an in depth look at everything from the common tapeworm to the deadly sleeping sickness caused by the Trypanosoma brucei parasite. He shows us how amazing parasites truly are, even the disgusting ones. '' Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the host. '' Parasites are generally smaller than the host they live in. Sometimes they are even microscopic. Parasites are able to live in their hosts and reproduce quickly and in very large numbers without killing their host. Ofcourse, some parasites do kill their host and this is called parasitoidism.

Parasites can live on the surface of their hosts and they are called ectoparasite, for example, mites. Most however, live on the inside of the hosts like in their muscle tissues and organs. They are called endoparasites. ''Tapeworms, reaching up to sixty feet long, are the biggest parasites that live in humans.'' They intertwine their way in the human intestines and can live there and reproduce. Another common parasite are hookworms. ''Hookworms live inside 1.3 billion people.'' They also live in the intestines of humans.'' They use their powerful teeth to lacerate a patch of intestinal wall (inset) and drink blood from the wound.'' The blood fluke infects a lesser number of people. Around 200 million.

Insects house a lot of parasites.''Parasitic wasps lay their eggs inside caterpillars , and the larvae slowly devour their living hosts before crawling out and weaving cocoons.'' Other insects are subjected to parasitic hosts as well. These include flies and mosquitos. A lot of the parasites go on to live into a bigger host after living in insects by making them ''stupid and foolhardy'' so that they can be easily preyed on. All parasites are not little and live inside hosts. For example, cuckoo birds are parasites although they don't live inside other animals. They lay their eggs in the nests of other birds and and trick them into taking care of them. In this way ''they steal parental care.''

This book relates to many scientific concepts such as evolution. Parasites are amazing in this way. They can build up defenses and evolve so that vaccines which used to kill them, no longer have any effect. They can also physically adapt to be able to survive in their hosts. ''There are 5,000 know species of tapeworm that live in various animals, and probably many thousands more still await discovery. Each one has a head specially adapted for lodging itself in its host's body.'' The blood fluke parasite travels through a number of hosts in its lifetime. "Its eggs hatch in fresh water and the young parasite seeks out a snail. Inside the snail, the parasite passes through several generations before producing a missile-shaped stage called cercaria. The cercaria then penetrates the human skin and becomes an adult that finally ends up in the veins of its human host.'' Parasites are incredible in the way they work. For example, the Trichinella parasite actually coils up inside individual muscle cells when they are in their larvae phase and completely take control over the muscle's DNA so that they can live more comfortably.

This book did effect science and society. All you have to do is look at its praising.

''Christopher Wills author of Yellow Fever, Black Goddess Bacteria and viruses have received all the press when it comes to plagues. In this vividly written book, Carl Zimmer explores the complex world of worms, protozoa and other terrifying creatures that pose an equally great public health threat around the world. These organisms are even more subtle and challenging enemies, and Zimmer provides an excellent introduction to them.'' Another one is ''Paul Hoffman author of The Man Who Loved Only Numbers Carl Zimmer is one of the finest, most engaging science journalists today. He has demonstrated once again his ability to present scientific concepts in arresting, understandable prose.''

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