Parasites and Humans: Why Can’t We All Just Get Along?
The definition of a parasite is: “an organism that lives on or in an organism of another species, known as the host, from the body of which it obtains nutriment.” (Dictionary.com,2012) There are several kinds of parasitic relationships in the world. Mutualism is one of them. This occurs when each member of the association benefits the other. Can humans and parasites have a mutualistic relationship in medicine? Dating back to the B.C. era it has been believed that parasites, most commonly leeches and maggots, were the cure for various maladies. Leeches at one time were thought to cure everything from obesity to mental illness. In the early 20th century there was no longer a need for parasites with the medical and technological advances we were making. Their popularity has begun to grow since the 1980s and is seen more often in medical practice.
Some parasites, over the course of history, have proven to hold a symbiotic relationship with the human body in medical applications. Prior to the days that we think of as modern medicine, parasites were used for many things in medical practice. One example is leeches. The use of leeches in medicine started around 2,000 B.C. with the Greek and Roman physicians. During the medieval times they were very prevalent in the household medicine cabinets as they were used on a regular basis to treat many different ailments. (Jaffari, M. 2012) As modern medicine emerged parasites were viewed as a bad thing. Things we did not want inside us or around us. We discovered many ways to eradicate them from our bodies, thus also eradicating them from medicinal use. In more recent years testing is being done especially with the helminth (worm) species of parasites. These parasites are being used to treat medical conditions such as ulcerative colitis, vascular diseases and allergies, just to name a few, with very interesting results. It’s beginning to seem as if humans and parasites in some applications can benefit each other after all. The use of parasites to treat ailments has been around for centuries. It is thought to date back as far as the Stone Age. The first written reference of this was in a medical poem by Nicander of Colophon (185-135BC). This poem referenced leeching (bloodletting) in particular. It is believed that all ancient civilizations used bloodletting in their medical practice. In ancient Greece they believed in the Humoral Theory. This theory stated that the body was made up of four humors; these were blood, phlegm, black bile, and yellow bile and you became ill because these humors were out of balance. The leeches were used to keep these humors in balance; thus, keeping the patient healthy. During the early nineteenth century in Europe it was not uncommon to find leeches in people’s medicine cabinets. The use of leeches during this time was very prevalent and they were believed to be almost a “cure all”. Bloodletting became so popular in Europe, that the commercial trade in leeches became a major industry. France during this era suffered such a shortage of leeches that they had to import 41.5 million of the parasites. Due to the extremely high demand for this product, the medicinal leech almost became extinct in Europe. When the numbers being harvested from the wild became insufficient, some countries started the practice of leech farming. (El-Awady, 2003)
Leeches were not the only parasite that received high acclaim for medical uses. The maggot has been known for its healing ability since the 16th century. In 1917, Dr. William S. Baer made an incredible observation while working as a physician during World War I. Two soldiers were brought into the hospital, both having compound fractures to their femurs and very large wounds to the abdomen. It was discovered that these two soldiers had been wounded in battle seven days prior but because of the over growth in the...
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