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PEST & PARASITES Objectives Distinguish between pests and parasites. Discuss the types of micro organisms that can cause disease Describe how our body responds to infection Explain how a vaccination works Explain how AIDS is caused and its dangers PESTS They are a nuisance. They affect us in a negative way. Common household pests include: - flies - rats - mosquitoes - cockroaches Parasites These are micro organisms that harm other living organisms. They live on or in that particular organism, also known as the host. * Note: Unlike parasites, pests do not cause diseases; they can transmit organisms that do. What types of micro organisms cause disease? BACTERIA VIRUSES FUNGI PROTOZOA Bacteria & Viruses Bacteria are unicellular organisms that multiply and release toxins. Not all are harmful- some exist naturally in the body. *bacterial diseases- typhoid, cholera, TB Viruses are smaller than bacteria. They invade living cells and cause more harm. *viral diseases-AIDS, measles, influenza (flu) How does the body respond to being infected? We detect these foreign bodies and destroy them. These harmful micro organisms have a chemical marker on their surface called an antigen. An antigen is a substance that prompts the generation of antibodies and can cause an immune response. Immunity Immunity is the protection against diseases by antibodies. They are two types: - natural -artificial Natural immunity Natural passive immunity involves antibodies passing directly from mother to the foetus, through the placenta and later in the breast milk. Natural active immunity involves the white blood cells ( lymphocytes) producing antibodies that destroy the antigens. Artificial immunity Artificial passive immunity occurs when the body is injects with antibodies produced by other organisms. Artificial active immunity occurs when the body is injected with weak strains of the pathogen. we make antibodies and memory cells against it so we can become immune to the actual disease. It is also known as a vaccination. Which type of immunity is seen here? Acquired immune deficiency syndrome This is a disease caused by the Human Immunodeficiency Virus (HIV). This virus causes severe weakening of the body’s immune system. This results in the body not being able to produce antibodies and therefore becoming vulnerable to many diseases. SANITATION Objectives Describe the conditions which promote the growth of micro organisms Discuss the principles of food preservation Discuss conditions that encourage the breeding of household pests Discuss the different types of waste Discuss the need for personal & community hygiene. Food spoilage When micro organisms feed on our food it spoils. This action is caused by: -the micro organisms first breaking down food using digestive enzymes. -then absorbing the soluble material Growth of micro organisms The factors that influence this growth are: Temperature Moisture Oxygen * Most micro organisms develop rapidly in moist conditions, because they need water to germinate and grow. How can we preserve food? Canning Pickling Freezing Salting Drying Adding sugar Adding preservatives Refrigeration Household pests Can you recall some of these pests? Household pests are a nuisance because of the economic damage they cause. They thrive best in dirty places filled with garbage; these conditions provide good breeding grounds. Think about these conditions, how are pests encouraged to breed there?? How can they be controlled? Sanitary- keeping the surroundings clean Chemical- using pesticides Biological-using other animals to catch the pest *Can you think of examples of each??? Pollution Pollution results from waste substances of human activities. They are harmful to all living organisms & the environment. These waste substances can be: -domestic -biological -industrial Hygiene Micro organisms and pests, if given the right conditions to thrive can cause diseases Mosquitoes can cause malaria, dengue fever Rats can cause leptospirosis Other micro organisms can cause cholera, typhoid and food poisoning What are the symptoms of these diseases?? Personal hygiene Can you make a list of things that you can do to prevent illness from micro organisms and pests??? Community hygiene The members of your community can also play a role in the prevention of diseases. Can you think of some of the ways to dispose of this waste?
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