All the living organisms are dependent on each other in obtaining their food and nutrients. For this, they have developed some associations between them. And parasitism is one of the associations in which one benefits (parasite) while the other is harmed (host). The damage they do ranges from minor to life threatening. The word parasitism is of Greek origin and is meant para- beside, sitos- food. The parasitic associations are of two types, one is the ectoparasites that feeds upon the body surface of the host e.g. mosquito, tick, or leech. Usually ectoparasites do not cause disease but they role as vectors for disease causing agents, for example the mosquito that transmits plasmodium, which causes malaria. And the second one is the endoparasites that feed inside the host body e.g. tapeworms, hookworms, and flukes. They feed within the organs or tissues of the host and may cause laziness in working, bad food utilization, and they may also cause chronic problems.

The historical information on parasitology was collected from the study of fossils. Egyptian records on parasites were the first written records, dated from 3000-400BC, roundworms, threadworms and some tapeworms were known parasites at that time. Around 300 B.C. Chinese physicians were known to parasites. Arabic physicians also have informative knowledge on parasites. Francesco Redi (1626-1697 AD) was the father of modern parasitology. He made many of dissections and described approximate 108 species of parasites. The major explanation he made was that the parasites produce eggs and gave a clue for the rejection of the theory of spontaneous generation, later this theory was rejected by Louis Pasteur in 1859. From the first known parasite to these days, a number of discoveries have been made in the field of parasitology. The invention of microscope made easier the explanation of the morphology, detection and diagnosis of any parasite. Incorporation of other fields of science made more advancement in the field of parasitology.

Parasitic diseases are considerably a major problem in the health. There is a worldwide challenging situation from the parasitic infectious diseases. The internal parasites can decrease an animals productivity and may also cause lower working efficiency, poor food utilization, chronic diseases and death may occur due to blood clotting. About 807-1221 million people of the whole world are infected from ascariasis. Malaria is also a major disease and according to the report of WHO in 2010 there are around 660 000 deaths and a great number of deaths were occurred in Africa. There are about 10,000 new cases of trypanosomiasis every year. Skin parasites are found in endothelial cells of the capillaries of the infected site, nearby lymph nodes, within large mononuclear cells, in neutrophilic leukocytes, and free in the serum exuding from the ulcerative site. But complications of skin parasites are very rare. A number of parasites are transmitted by the food items. Cryptosporidium spp., Toxoplasma gondii and Entamoeba histolytica and few roundworms and tapeworms are common parasites that are transmitted by food. Polluted water can serve as an origin of many parasites. The infections through the contaminated water cause severe diseases and even death in some case. Common diseases transmitted through the polluted water are amebiasis, giardiasis and schistosomiasis.

There are several clinical methods present to diagnose parasitic infections that rely on symptoms, history and geographic position of the patient. Microscopy is the oldest and authentic way to detect parasites from stool and blood samples. But not all the time microscopy is an effective tool so for the purpose, serological tests may be applied for further diagnosis. Serological tests include ELISA, immunofluorescence tests, complement fixation test, haemagglutination and western blot. The blood test for parasite detection, roundworms, hookworms and some helminthes may be found and sometimes CBC gives a high ESO count. In blood test fluctuated level of vitamins, minerals, enzymes and antibodies can indicate the presence of parasitic infection. When there is a parasite infection the antibodies level should be very high as compared to normal situations, so the immunological profile can also help to diagnose parasitic infection. Some parasites can also be detected with the help of CT scans and from MRIs. A CT scan of eye can show trapped ocular larva migrants, often mistakenly as retinoblastoma.

Biotechnology has brought a revolutionary change in the field of parasitology in diagnostic methods as well as in drug designing against the parasites. Biotechnology interacting our lives in different ways such as in the production of new and improved food and food products, biological chemical production, biopharmaceutical, disease resistant plants and livestock, diagnostics and detecting genetic diseases. And the most advanced applications of recombinant DNA technology and stem cell therapies. On the basis of new researches in biotechnology, this is an assumption that biotechnology will be a key technology for the 21st century and the future science.

Historically the use of biotechnology is very old. The word biotechnology was first time used in 1917-19, but as a subject it was started in 1970s. The history of biotechnology has three ages, (1) Ancient biotechnology, is based upon the civilization of human and selecting best breeds of animals and crops, (2) Classical biotechnology, refers to as the commercial productions specially of fermented products, and (3) the modern biotechnology was begun with the invention of microscope and the discovery of genetic material (DNA and genes) and now are moving on towards new researches.

Biological processes, products and services play an important role in nearly all areas of daily life, whether it is production of food or the treatment of a disease. Biotechnology is one of the most used technologies in our life that ensures secure life from diseases and a clean and better environment. The new advancements in medical biotechnology are incorporated with the old methods and some are replaced by the new methods. Pharmacogenomics, gene therapy, stem cell therapy, nanotechnology and new drug delivery systems (e.g. microspheres, tiny holes large enough to carry and deliver drugs to the targets) are the new approaches in health biotechnology.

With the incorporation of biotechnology in parasitology, it brought a revolution in diagnosis of parasitic infections and also in prevention and treatment. Techniques of biotechnology in parasitology are mostly being used with old conventional methods for accurate diagnosis and treatments.

The application of biotechnology in parasitology provided significant breakthroughs in vaccine development. Antigen vaccines have been developed against protozoan, cestode, nematode, trematode, and arthropod parasites. Recombinant DNA technology, chemistry of proteins, monoclonal antibodies and immunochemistry has played important role in the development of antigen vaccines. The use of monoclonal antibody and genetic engineering provided the tools to overcome the problems in identifying antigens. The antiprotozoal vaccines are based on killed parasites or refined parasite antigens. Gene silencing of the gene having pathogenic effect or supporting the pathogen is also can be used but this method is still in clinical trials to make its practical use.

To define vaccine at commercial level is the difficulty, so government regulated campaigns are required for parasite control by vaccines. In such conditions vaccine should be inexpensive, simple to use, stable under harsh environmental conditions and must have a long lasting efficacy.

Biotechnology enabled us to prevent lives from diseases and infections caused by the parasites, making modification to the genetic makeup of a host that can produce organisms that are genetically resistant to the parasites. Vaccination has helped in prevention from parasitic infections, so having a well managed and secured life. Future research will examine the prospects for delivering the vaccines using live recombinant bacterial and viral vectors. Other drug delivery methods (microspheres, nanotechnology etc) developed by biotechnology can be used for rapid cure. Biotechnology is proving as a revolutionary science and playing its important role in parasitology.

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