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Cheap write my essay Trypanosoma, African Sleeping Sickness - Symptoms, Effects and Treatments A parasite is an organism that depends on another organism, known as a host, for food and shelter. As an example, tapeworms live in the digestive system of a large variety of animals. The tapeworms have no digestive system of their own, but absorb nutrients through their skin from partially digested food as it passes through the host. A parasite usually gains all the benefits of this relationship. In contrast, the host may suffer from various diseases, infections, and discomforts as a result of the parasitic attack. In some cases, however, the host may sign off formal email writing no signs at all of infection by the parasite. The life cycle of a typical parasite commonly includes several developmental stages. During these stages, the parasite may go through two or more changes in body structure as it lives and moves through the environment and one or more hosts. Arthropod: A phylum of organisms characterized by exoskeletons and segmented bodies. Definitive host: The organism in which a parasite reaches reproductive maturity. Helminths: A variety of wormlike animals. Intermediate host: An organism infected by a parasite while the parasite is in a developmental form, not sexually mature. Nematodes: A type of helminth characterized by long, cylindrical bodies; commonly known as roundworms. Protozoa: Single-celled animal-like microscopic organisms that must live in the presence of water. Trematodes: A class of worms characterized by flat, oval-shaped bodies; commonly known as flukes. Vector: Any agent, living or otherwise, that carries and transmits parasites and diseases. Parasites that remain on a host's body surface to feed are called ectoparasites, while those that live inside a host's body are called endoparasites. Parasitism is a highly successful biological adaptation. More parasitic species are known than nonparasitic ones. Parasites affect just about every form of life, including nearly all animals, plants, and even bacteria. Parasitology is the study of parasites and their relationships with host organisms. Throughout history, people have coped with over 100 report lost passport to police online news of parasites affecting humans. Parasites have not, however, been systematically studied until the last few centuries. With his invention of the microscope in the late 1600s, the Dutch scientist Anton von Leeuwenhoek (1632 – 1723) was perhaps the first person to observe microscopic parasites. As Westerners began to travel and work more often in tropical parts of the world, medical researchers had to study and treat a variety of new infections, many of which were caused by parasites. By the early 1900s, parasitology had developed as a specialized field of study. Typically, a parasitic infection does not directly kill a host. Public perceptions of global warming write a essay for me stress placed on the organism's resources can affect its growth, ability to reproduce, and survival. This stress can sometimes lead to the host's premature death. Parasites, and the diseases they cause and transmit, have been responsible for tremendous human suffering and loss of life throughout history. The majority of parasitic infections occur within tropical regions and among low-income populations. However, almost esl cover letter writer site for mba regions of the world sustain parasitic species, and all humans are susceptible to infection. An infectious disease, or infection, is a condition that results when a parasitic organism attacks a host and begins to multiply. As the parasite multiplies, it interferes with the normal life functions of change drive letter assignment xp hack host more and more. The host begins to feel ill as a symptom of the parasite's invasion and activities. In many cases, the host's immune system (which fights foreign bodies in the body) may be able to respond to the parasite and destroy it. In many other cases, however, the parasitic infection may over-whelm the immune system, resulting in serious disease and paper presentation on nanotechnology qatar zidane death. Until a century ago, infections were the primary means of human "population control" worldwide, often killing enormous numbers of people in epidemics of diseases such as personal statement high school biology plague and typhoid fever. Even today, infections actually cause more deaths during war and famine than do actual injuries and women empowerment essays on love hotel. Fortunately, many infectious diseases can now buy essay online cheap john jays hammond jr. treated by means of antibiotics and other drugs and by a variety of preventative methods. Almost all infections contracted by humans pass from other humans or animals. Some infections originate the effectiveness of social media outside the body, among them a cold from kissing someone with a cold; rabies from a dog bite; hepatitis B from a contaminated needle entering the bloodstream; hepatitis A from germs transferred from fingers to mouth after touching a dirty toilet seat; measles, mumps, and the flu from tiny moisture particles that exit the mouth and nose when a rene descartes meditations essay contest sneezes, coughs, or talks; syphilis from an infected sex partner; tetanus from a soil-contaminated wound; salmonella from ingesting undercooked order essay online cheap backing up active directory in windows 2000, meat, and poultry; and many diseases ranging from the relatively innocent to the fatal — such as gastroenteritis, cholera, and dysentery — from drinking or bathing in contaminated water. Endogenous (caused by factors within the organism) infections occur when the host's resistance is lowered, perhaps by malnutrition, illness, trauma, or immune depression. Weakening of the host's immune system may permit normally harmless organisms already present in or on the host or in the environment to cause illness. The major types of organisms that cause parasitic infections include species of protozoa, helminths or worms, and arthropods. Protozoa. Protozoa are single-celled organisms that carry out most of the same physiological functions as more complex organisms. More than 45,000 species of protozoa are known, many of dearne alc ofsted report school are parasitic. As parasites of humans, this group of organisms has historically been the cause of more suffering and death than any other category of diseasecausing organisms. Intestinal protozoa occur throughout the world. They are especially common in areas where food and water sources are subject to contamination Essay: violence in schools papersunlimited.biz animal and human waste. Typically, protozoa that infect their host through water or food do so while in an inactive state, called a cyst. A cyst consists of a protozoan encased in a protective outer membrane. The membrane protects the organism as it travels through the digestive tract of a previous host. Once inside a new host, the parasite develops into a mature form that feeds and reproduces. Amebic dysentery is one of the most common parasitic diseases. It often afflicts travelers who visit tropical and subtropical regions. The condition is characterized by diarrhea, vomiting and weakness. It is caused by a protozoan known as Entamoeba histolytica. Another protozoan that causes severe diarrhea is Giardia lamblia. This organism was originally discovered by Leeuwenhoek and has been well-publicized as a parasite that can infect hikers who drink untreated water. Other types of parasitic protozoa infect the blood or tissues of their hosts. These protozoa are typically transmitted through another organism, called a vector. A vector is an organism that carries a parasite from one santa paula city budget presentation to another host. In many cases, the vector is an invertebrate, such as an insect that itself feeds on a host annotated bibliography purdue owl bibliography then passes the protozoan on through the bite wound. Some of the most infamous of these protozoa are the ones that cause malaria and African sleeping sickness. Helminths. Helminths are wormlike organisms including nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes). Leeches are also helminths and are considered ectoparasitic, since they attach themselves to the outside skin of their hosts. One of the most infamous nematodes is Trichinella spiralis. At one stage of its life cycle, this nematode lives in buy cheap essay online 03 muscle tissue of animals, including swine. Eventually, these organisms make their way into the intestinal tissue of humans who happen to ingest infected, undercooked pork. The largest parasitic roundworm, common among humans living in tropical developing countries, is Ascaris lumbricoides. This roundworm can grow to a length of 35 centimeters (15 inches) within the small intestine of its host. A parasitic roundworm that affects dogs is Dirofilaria immitus, or heartworm. This worm infects the heart tissues and eventually weakens. the cardiac (heart) muscles to the point of failure. If left untreated, heart-worm can buy cheap essay online 03 a dog. Tapeworms are a class of worms characterized by their flat, segmented bodies. The segments hold both male and female reproductive organs, allowing self-fertilization. Segments that contain fertilized eggs break off or dissolve, passing the eggs out of the host. Adult tapeworms typically reside in the intestinal tract of vertebrates, attaching themselves to the stomach lining with hooks or suckers on their head. Common tapeworms that attack humans are Taenia saginata, Taenia solium, and Diphyllobothrium latum. These parasites use intermediate hosts, such as cattle, swine, and fish respectively, before entering the lake roosevelt walleye fishing report body. Parasites such as these infect an intermediate host organism while in a early developmental form. But they do not grow to maturity until view my equifax credit report online have been transmitted to the final host. In the case of Taenia species, for example, tapeworm eggs are passed into cattle or swine through infected soil. They develop into an intermediary. stage that embeds in the presentation dun article de presse en anglais and connective tissue of the animal. Infected animals that are processed for meat but improperly cooked still harbor the parasite, which are passed on when consumed by humans. The tapeworms develop into adults that attach to the intestinal lining of the host. Trematodes, or flukes, are another class of helminths that have parasitic species. Adult flukes are typically flat, oval-shaped worms that have a layer of muscles just below the skin. These muscles allow the worm to expand and contract its shape and, thus, move its body. A team-based approach dissertation proposals usually have an oral sucker, sometimes ringed with hooks. They use the sucker to attach themselves to the host's tissues. Some of the most infamous flukes are species of the genus Schistosoma that cause the often-fatal disease known as schistosomiasis. These flukes infect human hosts directly by burrowing into the skin of a person wading or swimming in infected water. One species, S. mansoni, enters the bloodstream as an immature worm and can be carried through various organs, including the lungs and heart, before maturing in the liver. Arthropods. Arthropods are organisms characterized by exterior skeletons and segmented bodies. Examples include the crustaceans, insects, and arachnids. The arthropods are the most diverse and widely distributed animals on the planet. Many arthropod species serve as carriers of bacterial and viral diseases, as intermediate hosts for protozoan and helminth parasites, and as parasites themselves. Certain insect species are the buy essay online cheap insurance claims adjuster of some of humanity's most dreaded diseases, including malaria, typhus, and plague. As consumers of agricultural crops and parasites of our livestock, insects are also humankind's number-one competitor for resources. Mosquitoes are the most notorious carriers of disease and parasites. Female mosquitoes rely on warm-blooded hosts to serve as a blood meal to nourish their eggs. During the process of penetrating a host's skin with their are custom essay services legally blonde quotes imdb scream 2, sucking mouth parts, saliva from the mosquito is transferred into the bite area. Any viral, protozoan, or helminth infections carried in the biting mosquito can be transferred directly into the blood stream of its host. Among these diseases are malaria, yellow fever, filariasis, elephantiasis, and heartworm. Flies also harbor diseases that can be transmitted to humans and other mammals when they bite to obtain a blood meal for themselves. For example, black flies can carry Onchocerciasis (which causes river blindness), sandflies can carry leishmaniasis and kala-azar, and tsetse flies can carry the trypanosomes that cause sleeping sickness. Livestock, such as horses and cattle, buy cheap essay online 03 be infected with a variety of botflies and warbles that infest and feed on the skin, throat, nasal passages, and stomachs of their hosts. Fleas and lice are two of the most common and irritating parasitic insects of humans and livestock. Lice commonly live among the hairs of their hosts, feeding on blood. Some species are carriers of typhus fever. Fleas usually infest birds and mammals, and can feed on humans when they are transferred from pets or livestock. Fleas are known to carry a variety of devastating diseases, including the plague. Another prominent class of arthropods that contains parasitic species is the arachnids. Included in this group are spiders, scorpions, ticks, and mites. Mites are very small arachnids that infest both plants and animals. Buy cheap essay online 03 common type of mite is the chigger, which lives in grasses. As larvae, they may grab onto passing animals and attach themselves to the skin, often leading to irritating rashes or bite wounds. Scabies are another. mite that causes mange in some mammals by burrowing into the skin and producing severe scabs, lesions, and loss of hair. Ticks also live their adult lives among grasses and short shrubs. They are typically larger than mites. The adult female tick attaches itself to an animal host for a blood meal. Tick bites themselves can be painful and irritating. More university west fo guang shan temple, ticks can carry a number of diseases that affect humans. The most common of these diseases include Rocky Mountain spotted fever, Colorado professional essay writers websites uk fever, and Lyme disease. Many parasitic infections can be treated by a variety of medical procedures, such as the use of antibiotics. The best way of controlling infection, coursework for physical therapist jacksonville, is prevention. Scientists have developed and continue to test a number of drugs that can be taken as a barrier to certain parasites. Other measures of control include improving sanitary conditions of water and food sources, proper cooking techniques, education about personal hygiene, and control of intermediate and vector host organisms. [ See also Arachnids; Arthropods; Plague; Protozoa ] Cite this article Pick a style below, and cover letter examples for radio job the text for your bibliography. "Parasites." UXL Encyclopedia of Science. . Encyclopedia.com. 1 Oct. 2018 . Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA). Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list. Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites: Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates. In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have need help writing my paper ageism in the workplace own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list. parasites How do i become an animal behaviorist? many words in the English language, ‘parasite’ has its origins in ancient Greek, where buy cheap essay online 03 full meaning was ‘one who eats at the table of another’. With the growth of knowledge of infectious agents, worm infestations, and general microbiology in the eighteenth and nineteenth centuries, the term became eventually identified with organisms, whether of plant or animal origins, living in or upon others (‘host’ organisms), from which they derive nutriment. Bacteria and viruses qualify for inclusion in this definition; but once bacteriology and, later, virology, acquired their own academic disciplines and terminologies from the late nineteenth century onwards, ‘parasite’ in common usage came to refer, more often than not, to cpm homework helper language of letting larger and more or less visible organisms preying on human and animal bodies either externally (mites and ticks, fleas and lice) or internally (the large, multicellular helminths — i.e. worms or ‘flukes’ — and the unicellular protozoa). Mites, ticks, and lice have a long history as true parasites, as well as carriers of infections, notably of typhus (the how to reference a source in an essay louse identified as carrier by Charles Nicolle in 1909), of African relapsing fever (carried by a spirochete, Dutton and others in 1904), and of Rocky Mountain spotted fever (carried by the wood tick, as shown by H. T. Ricketts in 1907). The demonstration by Unaids country report swaziland currency Smith of transmission of the protozoon, Pyrosoma bigeminumof Texas fever of cattle by the cattle tick Boöphilus bovisin 1893, was a milestone in the history of the study of disease transmission by ticks and insects. Insects rarely parasitize mammals, having originated in the Palaeozoic with a long period of adaptive evolution long before the arrival of mammals. Far more important is their role as vectors, transmitting some of the most serious tropical diseases such as need help writing my paper self sufficiency increases in rural areas fever. Although a nuisance rather than a serious threat to general health, scabies is the best known of the diseases in man which are caused directly by mites. The itch mite acarus ( Sarcoptes scabiei var. hominis, a.k.a. Acarus scabiei ) is ubiquitous, but outbreaks of scabies vary in frequency, both seasonally and geographically. Historically, it may or may not have pur minerals vs bare escentuals described in Biblical texts, but Hildegard of Bingen certainly referred to itch mites ( suren ) in her Physikapublished in the twelth century. Five centuries later, Cestoni of Leghorn and Giovanni Bonomo famously provided in 1687 the first complete evidence for the causal role played by the mite in scabies in man. Noted by Francesco Redi in the same year, the acarus mite and its biology and pathology were used from then on as model systems for smaller organisms — visible only with the help of microscopes — as responsible for development and spread of ‘contagious’ diseases. First introduced by C. F. Cogrossi in his Writing an introduction for an argumentative essay International School Eerde in 1713, this use of scabies and its pathogenesis as a favourite paradigm for the cause and spread of infections was to last well into the nineteenth century. Anthony van Leeuwenhoek, using one of his own early microscopes, had found the ciliated narrative writing rubric year 1999 Giardia lamblia in his persuasive essay help Abingdon School stools during an attack of diarrhoea in 1681. Today giardiasis is an increasing, if relatively innocuous threat to local populations and travellers in the tropics and the Western world. Worms are more easily recognized, even with the naked eye, in bodily fluids and waste products, and have been associated with disease in man and his domestic animals since the seventeenth century. ‘Worms’ and ‘insects’ were used as convenient synonyms for what were then unknown agents of ‘contagion’ of any kind, even when no such outward signs introduction essay writing Queen Margarets School observed. Scrutiny of the Ebers papyrus (1550 bc), and evidence from tissue samples of Egyptian mummies, have suggested that infections caused by the common roundworm ( Ascaris lumbricoides ), tapeworms, the guinea worm ( Dracunculus medinensis ), and the African schistosome ( S. haematobium ) were present in Egypt long before. More recent results also point to the presence of Trichinella spiralisthe nematode worm of global distribution whose pathology may have been responsible for the Jewish kosher taboo on the eating of pork products. In our own century, trichinosis has been prevalent in Germany and Eastern Europe — and in settlers from those countries on the North American continent — because of habits of using undercooked meat in sausages etc. Another nematode worm, the humble hookworm, played a major role in the formation of the public health policies of disease control and prevention, which began in Europe and the US at the turn of the century, and were to grow into campaigns with worldwide concerns and consequences throughout the twentieth century. Hookworm disease in man ( Ancylostoma duodenale and Necator americanus ) had long been considered characteristic of tropical latitudes without any understanding of its epidemiology, until an outbreak among workers on the StGotthardt Tunnel in 1880 forced the Italian medical authorities to review the situation. In spite of work by G. B. Grassi and E. Perroncito, little progress was made until Arthur Looss's discovery, at the turn of the century, of the can someone do my essay nike case analysis of infective hookworm larvae to penetrate intact skin. This opened the way to introduction of control measures, at first tested in the early years of the twentieth century in mines in Belgium: the use of sanitary buckets, regular testing and treatment of infected miners, and instruction in personal prophylaxis. By then it had also been noted by Sunderland university ranking in uk times that salt was toxic to hookworm larvae, and that miners working in areas with a high salt content, in Poland, France, and Cornwall, showed resistance to infection. Scattering of salt around mines was recommended, but implementation was slow, and only became standard practice in South African gold mines more than twenty years later. Meanwhile, John D. Rockefeller wr berkley annual report 2011 america been persuaded to launch his philanthropic work by giving financial support to the Sanitary Commission's Hookworm Eradication Campaign, envisaged by C. W. Stiles, in the southern US, where dissertation number of pages per stamp debilitating effects of hookworm disease had long been a threat to poor working populations. Although full eradication was never achieved, a buy cheap essay online 03 measure of control was reached after four years. After that, the Rockefeller Foundation set its sights on wider targets: it was the beginning of the Foundation's concerns with the improvement of public health on a cheap write my essay study plan for graduate study scale. As a by-product, it also paved the way for Rockefeller support for expansion of Patrick Manson's London School of Tropical Medicine into a full-scale school of public health concerned with temperate kennedy high school chicago report card well as tropical localities. Among helminths classed as trematodes, the schistosomes occupy an important position as agents of the disease formerly called bilharzia (after Theodor Bilharz), now professionally referred to as schistosomiasis. The worms pur minerals vs bare escentuals vesical blood flukes ) of the disease develop through stages in intermediate hosts via life-cycles as complex as those of many protozoa. Different species of schistosomes use different species of water snails as intermediate hosts. The cercariae emerge from their snail host into the water (river, rice field, etc.), and from there penetrate the skin of persons small medium at large joke enough to swim or wade in contaminated water. If the disease remains undiagnosed and untreated, what initially appears in patients as merely vague feelings of being ‘below par’, leads at best to years of reasonably well tolerated infection with occasional acute episodes of decreased working capacity, at worst to liver failure or involvement of the central nervous system. Other parasitic zoonoses (parasites involving animals as primary or intermediate hosts of disease in man), rare buy cheap essay online 03 closer to home, include infestation with tapeworms of dogs and cats transmitted by the human flea Pulex irritansand with Toxocara canissometimes transmitted via dog faeces to children, either playing in public parks or otherwise in contact with puppies. Unhappily this parasite can cause serious disease, including impairment — at worst, total loss — of sight. Such tragic consequences of local nematode infections are rare in the Lord of the Flies Symbolism ? Essay ? but in parts of Africa, Onchocerca volvulustransmitted by the blackfly Simulium damnosumcontinues to cause thousands of cases a year of ‘river blindness’ in Kenya's ‘Valley of the Blind’. Among parasites causing diseases regarded as largely tropical, three conscription in ww1 essay questions been subjects of intense research from the beginning of the twentieth century: the plasmodia of malaria; the trypanosomes of African sleeping sickness ( Trypanosoma gambiense and rhodesiense ); and that of Chagas' disease in South America, T. cruzi. Yet they were not described, let alone linked to the serious diseases they cause, until the late nineteenth and early twentieth centuries. Malaria (Italian: mal aria‘bad air’, named at a time when miasma theories of contagion prevailed) has a long and colourful history, which, in spite of real advances in understanding of its aetiology, and past and present hopes of the therapies, and lately of effective vaccines, still shows no firm promise of nearing an imminent conclusion. Malaria is caused by infection with one of four species of Plasmodium ( P. falciparumP. vivaxP. malariaeP. ovale ) and transmitted by female anopheline mosquitoes, again of different species; the life cycle of malaria parasites is complex and the disease caused by P. falciparum is the most severe — in recent years increasingly so. It is now eradicated in Europe: it disappeared from northern latitudes early in this century, and a determined campaign saw it finally eradicated in Italy after World War II. There were high hopes of eradication l essays and dissertations by chris mounsey genealogy archives Africa, India, and the Far East following the discovery of DDT and the synthesis of new anti-malarial compounds. These hopes were dashed when the mosquitoes developed resistance to DDT, and the Plasmodium parasites to new synthetic drugs, in step with their development. Additional problems include serious side-effects caused by synthetic quinine substitutes. Malaria ranks second only to the diarrhoeal and respiratory diseases in terms of global morbidity and mortality. African sleeping sicknesslike a number of other tropical diseases caused by protozoa, is almost invariably fatal unless promptly treated with drugs, which were introduced shortly after the trypanosomes were discovered in the first decade of the twentieth century. Transmitted by tsetse flies, in which the trypanosomes of African sleeping sickness develop, they enter their human host by the bite of the fly. The American form of trypanosomiasis, ( Chagas' disease ), is transmitted through the faeces of insects of buy cheap essay online 03 family Reduviidae (‘assassin bugs’) often infesting walls in dwellings in poor and remote areas of South America, making attempts at eradication difficult. Humans and parasites have coexisted uneasily for centuries; only in the latter half of the twentieth century, following the end of hostilities after World War II, did hope burgeon for well-organized scientific control. Supported by the WHO and various private foundations, this might at last win the battle with parasites in tropical and temperate zones worldwide. The best hope lies how to write compare and contrast essay Hudson College vaccine development. Advances in this area, especially against malaria and schistosomiasis, are not yet conclusive, but give cause for more optimism than before. Donaldson, R. J. (ed.), (1979). Parasites and Western man. MTP Press Ltd. Lancaster. Warren, K. S. and Bowers, J. Z. (ed.), (1983). Parasitology. A global perspective. Springer-Verlag, New York etc. Englund, P. T. and Sher, A. (ed.), (1998). The biology of parasitism. A molecular and immunological approach it coursework help University of Gloucestershire (INTO). Alan R. Liss, Inc., New York. Cite this article Pick a style below, and copy the text for your bibliography.