People, Parasites, and Plowshares: Learning from Our Body's Most Terrifying Invaders
Dickson D. Despommier
Format: PDF / Kindle (mobi) / ePub
Dickson D. Despommier's vivid, visceral account of the biology, behavior, and history of parasites follows the interplay between these fascinating life forms and human society over thousands of years. Despommier focuses on long-term host-parasite associations, which have evolved to avoid or even subvert the human immune system. Some parasites do great damage to their hosts, while others have signed a kind of "peace treaty" in exchange for their long lives within them. Many parasites also practice clever survival strategies that medical scientists hope to mimic as they search for treatments for Crohn's disease, food allergies, type 1 diabetes, organ transplantation, and other medical challenges.
Despommier concentrates on particularly remarkable and often highly pathogenic organisms, describing their lifecycles and the mechanisms they use to avoid elimination. He details their attack and survival plans and the nature of the illnesses they cause in general terms, enabling readers of all backgrounds to steal a glimpse into the secret work of such effective invaders. He also points to the cultural contexts in which these parasites thrive and reviews the current treatments available to defeat them. Encouraging scientists to continue to study these organisms even if their threat is largely contained, Despommier shows how closer dissection of the substances parasites produce to alter our response to them could help unravel some of our most complex medical conundrums.
needed. Transplanting pig islet cells into diabetic patients is one treatment that has been pursued, and it seems like a viable alternative if certain issues could be addressed. Early human clinical trials with this treatment were promising but quickly encountered several hurdles. The first was, of course, the fact that a pig donated the cells. Most of the time our immune system is really good at distinguishing between us and everything else, so immunosuppression of the recipient is necessary.
a small blood vessel. It is passively carried throughout the body by the circulation until it encounters the capillaries of the lungs. This stimulates the still-microscopic worm to penetrate out of the circulation and into the surrounding lung tissue. Then something fantastic happens: the worm turns on its cloaking device. It cannot be detected any longer by any branch of our immune system. From that point on, it can travel anywhere in the body without concern for waking up our immune system. It
periods of time in soil, making that the ideal medium for contaminating harvested crops. The rest of the story is easy to piece together. Some two billion people around the world harbor combinations of these three intestinal worms, making them, indeed, the unholy trinity. The Giant Intestinal Worm: Ascaris lumbricoides Imagine a smooth, pink-tinted worm about the size of a pencil (fig. 5.1). Now imagine that this same worm just crawled out of your left nostril! Sounds like your worst nightmare,
Giardia and Entamoeba histolytica, although these three can occasionally linger for up to several months in our blood or intestinal tract before we eventually fight them off. All these parasites happen to be single-cell organisms (protozoans). Granted, exposure to any parasite in this group could result in a protracted infection, but in the main, most of us manage to get rid of them in a relatively short period of time and go about our lives as if we had never encountered them. In contrast, there
expense. Most new drugs come from the research laboratories of the major pharmaceutical houses such as Pfizer, Merck, and GalaxoSmithKline. It currently takes many years to bring a promising compound from the bench to the pharmacy, even after all the science has been worked out and scale-up production methods have been established. That is because between 1957 and 1961, the drug thalidomide, a sedative used extensively by women during various periods of their pregnancies to alleviate morning