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Apart from the true monogenicgenetic disorders, environmental factors may determine the development of disease in those genetically predisposed to a particular condition. Stress, physical and mentalabuse, diet, exposure to toxins, pathogens, radiation and chemicals found in almost all personal care products and household cleaners are common environmental factors that determine a large segment of non-hereditary disease. Environmental factors such as the weather affect business interests. If a disease process is concluded to be the result of a combination of genetic and environmental factor influences, its etiological origin can be referred to as having a multifactorial pattern.
An example of an environmental trigger would be a component of a human's drinking water which holds the possibility of activating (triggering) a change in a person's body. These changes are mainly negative ones. Using this example, what is in the drinking water may affect one person entirely different than another -- someone may be affected greatly, whereas someone may not be at all.
An infectious disease is a clinically evident illness resulting from the presence of pathogenicbiological agents, including pathogenic viruses, pathogenic bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions. These pathogens are able to cause disease in animals and/or plants. Infectious pathologies are also called communicable diseases or transmissible diseases due to their potential of transmission from one person or species to another by a replicating agent (as opposed to a toxin).
Transmission of an infectious disease can occur through one or more of diverse pathways including physical contact with infected individuals. These infecting agents may also be transmitted through liquids, food, body fluids, contaminated objects, airborne inhalation, or through vector-borne spread. Transmissible diseases which occur through contact with an ill person or their secretions, or objects touched by them, are especially infective, and are sometimes referred to as contagious diseases. Infectious (communicable) diseases which usually require a more specialized route of infection, such as vector transmission, blood or needle transmission, or sexual transmission, are usually not regarded as contagious, and thus are not as amenable to medical quarantine of victims.
The term infectivitydescribes the ability of an organism to enter, survive and multiply in the host, while the infectiousness of a disease indicates the comparative ease with which the disease is transmitted to other hosts. Aninfection however, is not synonymous with an infectious disease, as an infection may not cause important clinical symptoms or impair host function.
Among the almost infinite varieties of microorganisms, relatively few cause disease in otherwise healthy individuals. Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. Infectious microorganisms, or microbes, are therefore classified as either primary pathogens or as opportunistic pathogens according to the status of host defenses.
Primary pathogens cause disease as a result of their presence or activity within the normal, healthy host, and their intrinsic virulence (the severity of the disease they cause) is, in part, a necessary consequence of their need to reproduce and spread. Many of the most common primary pathogens of humans only infect humans, however many serious diseases are caused by organisms acquired from the environment or which infect non-human hosts.
Organisms which cause an infectious disease in a host with depressed resistance are classified as opportunistic pathogens. Opportunistic disease may be caused by microbes that are ordinarily in contact with the host, such as pathogenic bacteria or fungi in the gastrointestinal or the upper respiratory tract, and they may also result from (otherwise innocuous) microbes acquired from other hosts (as in Clostridium difficilecolitis) or from the environment as a result of traumatic introduction (as in surgical wound infections or compound fractures). An opportunistic disease requires impairment of host defenses, which may occur as a result of genetic defects (such as Chronic granulomatous disease), exposure to antimicrobial drugs or immunosuppressive chemicals (as might occur following poisoning or cancerchemotherapy), exposure to ionizing radiation, or as a result of an infectious disease with immunosuppressive activity (such as with measles, malaria or HIV disease). Primary pathogens may also cause more severe disease in a host with depressed resistance than would normally occur in an immunosufficient host.
One way of proving that a given disease is "infectious", is to satisfy Koch's postulates (first proposed by Robert Koch), which demands that the infectious agent be identified only in patients and not in healthy controls, and that patients who contract the agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis. Koch's postulates cannot be met ethically for many human diseases because they require experimental infection of a healthy individual with a pathogen produced as a pure culture. Often, even diseases that are quite clearly infectious do not meet the infectious criteria. For example, Treponema pallidum, the causativespirochete of syphilis, cannot be
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Answers:Air pollution causes many respiratory diseases and even cancer. Semiconductor Chip Manufacturing is related to Birth Defects, Cancer and Miscarriages. Major disease this year in H1N1 flu and it is caused hygienic problem more than pollution.
Answers:1,b 2,f 3,a 4,d 5,d
Answers:i'm giving answers in point form. you can develop them into essays by further researching on your own 1. flooding treatment. farmers use excessive water to decrease the concentration of soil in the soil. disadvantage: continuous flooding treatment may introduce even more salt into the land. so it isn't that effective 2. sustainable use of land, allow the land to fallow instead of intensive farming. ii) can't think of anymore 3. green revolution, plus GM food, to increase world food supply. green revolution make use of chemical fertilizers and pesticide to ensure that the crops are not destroyed and enable more yield of crop. GM modify the genes of plant to make them resistant to pests or diseases. obstacle: chemical fertilizers and pesticide cause land pollution, possible health risks. the poor cannot afford chemicals and land into debts. ii) technology use in agriculture. use machineries like tractors, harvestors to attain higher crop yeild. use sprinklers and irrigation system to ensure enough water for crops. obstacle: not all countries and people in the world can afford such technologies. 4. i dont know the differences in using inorganic and organic fertilisers. sorry.
Answers:Acid Rain - Medium - It's a symptom of other more important things Air Pollution - med to high - it kills lots of people every year, particularly children and the elderly Drinking Water Quality - medium - in most cases it is easily resolved if we try Food Additives - med - depends what additives. Easy to avoid additives you don't want to have in your diet. Genetically Modified Foods - med to high - we don't know enough about them yet. History shows that releasing anything into an ecosphere where it does not belong can have disastrous effects. The arguments about feeding the third wolrd are largely marketing spin from the companies producing this stuff. Probably some useful technology to come, just not quite there yet in my opinion. Indoor Air Pollution - low - Easy to avoid Ozone Depletion - medium - serious but not as bad as it used to be Pesticides - medium - they leach into the water table and kill fish in rivers etc. Asbestos - low. Not so much of it about nowadays, not as dangerous as most people think and well controlled when they know it's there. Solid Waste - high - we're running out of landfill space. Needs better managing. Global Warming - VERY high - Probably the most dangerous thing threatening the human race. Maybe not the world but definitely the human race and a lot of other species. Ground-Level Ozone - low - again, easily avoided and dealt with if you try