Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Epidemiology wikipedia , lookup
Eradication of infectious diseases wikipedia , lookup
Compartmental models in epidemiology wikipedia , lookup
Infection control wikipedia , lookup
Hygiene hypothesis wikipedia , lookup
Public health genomics wikipedia , lookup
THE SEARCH FOR BETTER HEALTH (Last updated 5th May 2011 by SR/IR) Contextual Outline When physiological processes malfunction, the body tries to repair the damage. The process is similar in all living things and it is only when the process fails to contain the damage that disease can be recognised. Humans have long recognised the symptoms of disease both in themselves and the animals and plants around them. Since the beginnings of recorded history, they have noted the signs that reveal that the body is malfunctioning. Increasing understanding of the causes of disease together with accompanying advances in technology have changed approaches to treatment and management of disease. The search for measures to treat and manage diseases of humans and other organisms continues and this search is paralleled by continued refinements in technology. This module increases students’ understanding of the history, nature and practice of biology, the applications and uses of biology, and the implications of biology for society and the environment. Discuss the difficulties of defining the terms ‘health’ and ‘disease.’ Things to consider: - What does discuss mean? - Underline key words - Be succinct Defining the term health is not easy as there are many components which fall under health and some of these components are very subjective. According to the World Health Organisation, (WHO) “health is a state of complete physical, mental, and social well – being and not merely the absence of disease or infirmity.” This basically means that good health revolves around a biological, psychological and social well – being. Biological health: being active and free from pain. Psychological health: feeling happy, not depressed. Social well – being: interrelating within the community. Each of the above factors would all have slight different meanings to different people making the term health harder to define. Disease is also another word which is hard to define. Disease as a definition is a state of impaired functioning by interfering with the structure of organs, tissues or cells or by altering normal metabolism. This definition is subjective to the functioning of each individual. Meaning that one person may feel that they are sick while another person with the same symptoms does not feel sick. Outline how the function of genes, mitosis, cell differentiation and specialisation assist in the maintenance of health. Things to consider: - What does outline mean? - Underline key words - Ensure you write about each of the key components that assist in the maintenance of health. The function of genes, mitosis, cell differentiation and specialisation all assist in the maintenance of health. They are outlined as follows: Genes: Genes assist in the maintenance of health by ensuring that the correct proteins are produced in a cell. This enables all other cellular processes to continue and to maintain health within the organism. Mitosis: Mitosis assists in the maintenance of health by ensuring that genetic material is copied accurately when new cells are formed. These new genetically correct cells enable the organism to grow as well as repair any damaged cells or tissue. This therefore maintains health for the organism. Cell differentiation/specialisation: During the development of a cell the cell differentiates and becomes a specialised cell for a specific function. Genes release certain proteins which enable the cell to have a specialised function. Cell differentiation and specialisation is important in the maintenance of health as these cells enable the organism to grow as well as repair damaged cells or tissues. Cells may become specialised to fight of infection such as macrophages. Use available evidence to analyse the links between gene expression and maintenance and repair of body tissues. Things to consider: - What does analyse mean? - What is gene expression? - Underline key words and understand what the question is asking before you answer. - Draw a link between gene expression and repair of body tissue. Gene expression: is the entire process that takes the information contained in genes on DNA and turns that information into proteins. (The process of transcription and translation.) To maintain a healthy lifestyle the appropriate genes during mitosis must be expressed. If there is damage or no damage to cells or tissue it is still necessary for the appropriate genes to be expressed efficiently in order for necessary compounds to be produced and therefore a healthy existence. Example: During mitosis cells differentiate to have a specialised function. For example in order for muscles to contract they need the proteins called actin and myosin. The gene responsible for these proteins is “switched on.” The cell differentiates and becomes a specialised muscle cell. This relates to gene expression and the repair of body tissue in the sense that the gene responsible for the expression of actin and myosin was triggered. This resulted in the development of a specialised muscle cell, which in turn repaired the muscle tissue. Distinguish between infectious and non – infectious disease. Things to consider: - What does distinguish mean? - What are infectious and non – infectious diseases? - Be succinct Health and Disease HSC Core unit 3 The Search for Better Health (Supplementary notes compiled by IR 1/5/11) Health = state of physical, mental and social well-being Disease = any condition that impairs the normal functioning of an organism Causes of Disease: 1) Infection by parasitic pathogens (or infective particles) a) Microorganisms such as viruses, bacteria, fungi, protozoans or (prions, a proteinaceous infective particle). b) Macro organisms such as: i) endoparasites (flukes, tapeworms, round worms) ii) ectoparasites (lice, fleas, mosquitoes, ticks, mites). 2) Heredity -Chromosomal abnormalities, gene abnormalities, genetic diseases inherited on autosomes or sex chromosomes. 3) Nutrition -malnutrition, vitamin deficiencies, mineral deficiency, excessive or insufficient intake of food (obesity, anorexia, bulimia) 4) Physiological malfunction Congenital defect form birth, hormonal, nutritional imbalance, cardiovascular disease, toxic carcinogens (cancer), pollutants & drugs, degenerative ageing, physical damage from impacts or burns. 5) Environment a) Pre-natal environment i) Foetal abnormalities due to rubella in the mother ii) Foetal alcohol syndrome iii) Foetal heroin addiction b) Post-natal environment i) Stress related diseases (anxiety, hypertension, asthma, diabetes, gastrointestinal ulcers etc) ii) Sun damage (skin cancers, cataracts) iii) Noise damage (deafness) 6) Chemicals a) Heavy metal poisoning (mercury, lead etc) b) Drug abuse (tranquillizers, sedatives, narcotics such as morphine & heroin; stimulants such as caffeine, nicotine, amphetamines & cocaine; hallucinogens such as LSD etc; solvents and inhalants such as aerosols, petrol, glues). Non Infectious Diseases: are caused by some factor other than a pathogen Infectious Diseases: are caused by pathogens which invade the body then grow and multiply in the tissues Student worksheet Health = ........................................................................................................................................ Disease = ........................................................................................................................................ Causes of Disease: 1) Infection by 2) Heredity such as: 3) __________________ such as: 4) Physiological malfunction such as: 5) Environment a) Pre-natal environment b) Post-natal environment 2) Chemicals such as: Non Infectious Diseases: are caused by some factor other than a .............................................. Infectious Diseases: are caused by ................................. which invade the body then grow and multiply in the tissues INFECTIOUS Infectious diseases are caused by an infecting organism which usually invades the body. Infecting organisms can microscopic or macroscopic. A pathogen is an example of an infectious organism. They include; prions, viruses, bacteria, protozoans and fungi. NON - INFECTIOUS Non – infectious diseases are not caused by a pathogen and cannot be passed on from person to person. Non – infectious disease are usually the cause of genetic inheritance, nutritional deficiency and environmental factors. Examples include Down syndrome (genetic), anorexia (nutritional) and skin cancer (environmental). Explain why cleanliness in food, water and personal hygiene practices assist in control of disease. Things to consider: - What does explain mean? - Underline key words. - Understand the question before answering It is important that food, water and personal hygiene practices are maintained in order to assist in control of disease. Food is easily contaminated by visible applications such as dirt or insects or microscopic by micro – organisms such as salmonella. Hygienic handling of this food controls the spread of disease. Hygienic practices include; using clean utensils, not sneezing/coughing over food, not using food that has fallen on the floor, washing hands after being to the toilet, covering cuts and abrasions before preparing food and always placing perishable foods in the fridge/freezer. If these general hygienic practices were not followed populations could suffer from food poisoning and disease. It is these simple practices that control disease. Water is easily contaminated by pathogens such as Giardia and cryptosporidium. These pathogens are controlled by Sydney Water by constant water testing as well as being filtered and chlorinated before reaching the household. Sewage is also disposed of in a safe manner in order to control the spread of disease. Personal hygiene refers to the nature of keeping oneself clean. This includes washing hands after using the toilet, washing hands before preparing food, showering regularly and washing hands after you have been in contact with something dirty or a sick person. If this personal hygiene was not kept in order people would easily contract disease from infectious pathogens. Therefore it is important to maintain cleanliness in food, water and personal hygiene to assist in the control of disease. Identify the conditions under which an organism is described as a pathogen. Things to consider: - What does identify mean? - What is a pathogen? An organism that causes disease is known as a pathogen. For the pathogen to cause disease it must have the right conditions in order to multiply and transmit itself from organism to organism. Pathogens can come in the form of prions, viruses, bacteria, protozoans, fungi and parasites. These pathogens can either be microscopic or macroscopic, meaning they can be seen by the naked eye. Pathogens can be transmitted in the following ways: - Air - Water - Food - Direct contact - Vectors Identify data sources, plan and choose equipment or resources to perform a first – hand investigation to identify microbes in food or in water. Things to consider: - What does identify, plan and choose mean? - What are microbes? - Ensure you plan your own investigation as it is a HSC requirement Background: Microbe – an organism which is too small to be seen by the naked eye. Streaking: Streaking is the technique whereby you use the inoculation loop to streak an agar plate. Firstly the inoculation loop is placed in the blue flame of the Bunsen burner to sterilise the inoculation loop. (Kill off any pathogens) The inoculation loop is then swabbed across an area you are wishing to test, for example a piece of food or a water sample. Then you open the agar plate at a 45 degree angle and swap in a zig zag pattern in the middle of the agar. See p. 246 to 248. AIM: To identify a variety of microbes in food and water. MATERIALS: Sterile agar plates Inoculation loops Various water samples Incubator Bunsen Burner Food samples METHOD: 1. Collect a number of agar plates and place them under various conditions. For example in the science lab, near a rubbish bin or outside on the school oval. Expose each plate for the same amount of time. Keep one plate closed as a control plate. 2. Collect your plates close them and seal them with sticky tape. Once closed ensure you label your plates with your name, date and area of exposure. 3. Collect a number of agar plates to test the various water and food samples. Using the streaking technique collect a sample from the food and water sample and streak your various agar plates. Close your plate and label with your name, date and food/water you exposed your plate to. 4. Invert your plates and incubate for 24 hours. 5. Once incubated observe your agar plates for bacterial colonies. Colonies can be distinguished through their characteristics such as colour and texture. Count the number of colonies and record your observations in the results table. RESULTS: NO. OF COLONIES LOCATION COLOUR TEXTURE BRIEF DRAWING Gather, process and analyse information from secondary sources to describe ways in which drinking water can be treated and use available evidence to explain how these methods reduce the risk of infection from pathogens. Things to consider: - What does gather, process and analyse mean? - What does explain mean? - Underline key words - Understand what the question is asking before answering. Water is treated to remove impurities and microbes from causing disease to the general public. To prevent the spread of disease water companies take the following steps to prevent the spread of disease: - Coagulation and sedimentation - Filtration - Disinfection Coagulation involves adding certain chemicals to the treated water such as alum. The coagulating material causes dirt, plant debris and other organic matter to clump together and form what is known as a floc. As the water flows through the tanks the floc settles to the bottom and is removed. Filters are used to remove small particles such as viruses and protozoans, for example Giardia. Filters are usually comprised of a specialised membrane, a sand pebble mixture or activated carbon. The final step is to disinfect the water. Chlorine is the common chemical used in the disinfection stage. Ozone and U.V. radiation can also be used. Fluoride in some countries may be used to prevent tooth decay. Once disinfected, water is piped to homes and businesses. These are the main methods to reduce the risk of infections from drinking water. Not only are these steps followed but Sydney Water also incorporates strict controls on N.S.W drinking water. These include; fences around major dams to prevent contamination from animals, adequate distance from farming communities and distance from sewerage systems. These steps all prevent infection from pathogens. Describe the contribution of Pasteur and Koch to our understanding of infectious diseases. Things to consider: - What does describe mean? - Who are Pasteur and Koch? - Ensure you understand their work as scientists are regularly referred to in the HSC. Louis Pasteur and Robert Koch played a pivotal role to our understanding of infectious diseases. Louis Pasteur a French chemist discovered that most infectious diseases are caused by micro – organisms, or germs. This became known as Germ Theory. Through Pasteur’s research on fermentation he was able to identify and describe the micro – organisms that cause fermentation. During this research Pasteur also disproved the theory of spontaneous generation. Due to Pasteur’s knowledge of microbes and fermentation he was involved in many industries including the wine industry. Pasteur showed that microbes, which caused wine to spoil, could be killed by heating the wine to 55oC. This process was also applied to milk and beer and is now known as pasteurisation. Pasteur also demonstrated that anthrax a disease that affected cattle, sheep and horses was caused by a bacterium known as Bacillus anthracis. He developed a technique by weakening a strain of this bacterium and injecting it into certain animals. On one occasion he took 50 sheep and injected 25 of them with the weakened disease. Several days later he injected all 50 of the sheep with a strong dose of the disease. Pasteur predicted that 25 of the sheep would die. Subsequently 25 sheep did die and 25 survived. Today this process is commonly known as vaccination. Pasteur developed many vaccines including vaccines for anthrax, chicken cholera and swine erysipelas. Robert Koch was also heavily involved in microbial work, in particular anthrax. Koch was successful in isolating the bacterium from the blood of dying animals. He examined the blood under the microscope and identified active rod – shaped cells and resting spores. He concluded that all infected organisms contained these microbes, while healthy organisms did not. Koch also found that if blood taken from an infected organism was injected into another organism it would contract the disease. To prove that it was not another component of the blood Koch extracted the bacteria only and injected it into a healthy organism, subsequently causing the disease. From this research Koch provided step by step guidelines to prove that a particular micro – organism causes a particular disease. These are known as Koch’s postulates and are as follows: 1. The specific micro – organism must be present in all infected organisms. 2. The specific micro – organism must be isolated from the host and grown in a pure culture. 3. A healthy organism is then injected with the micro – organism. This organism must develop the same symptoms as previous infected organisms. 4. The specific micro – organism must be isolated from the second host and be the same species of micro – organism as the one originally injected. It was through the work of Pasteur and Koch, which laid the foundations for scientists to study micro – organisms. This has led to a greater understanding of infection control and hygienic practices. Perform an investigation to model Pasteur’s experiment to identify the role of microbes in decay. Things to consider: - What does perform mean? - What does identify mean? Refer to page 260 to 261. “Modelling Pasteur’s experiment.” Distinguish between: - Prions - Viruses - Bacteria - Protozoans - Fungi - Macro – parasites And name one example of a disease caused by each type of pathogen. Health and Disease HSC Core unit 3 The Search for Better Health (Supplementary notes compiled by IR 1/5/11) General Features of Pathogenic Organisms Viruses 0.01 – 0.3µm in size Lack cell membrane & cell structure 3 types (animal viruses, plant viruses, bacterial viruses (bacteriophages)) Outer protein coat containing nucleic acid, varying structure (see p9 Sakker et al, 1998) 2 phase life cycle o Exracellular phase – exists as inert infective particle o Intracellular phase – replicates DNA or RNA in host (see Fig 7.10 & 7.11 p. 355 BIF) Fungi 3.0 - 10µm diameter Can be unicellular e.g. yeasts or Multicellular such as moulds, mushrooms o Filamentous o Branching filamentous (hyphae, mycelium) o Hyphae septate (cross walls) in most species. Cells may be uninucleate or multinucleate Most fungi produce spores either in sporangium (see p357 BIF) or at tips of hyphae. Cell wall usually of chitin (some have cellulose) Heterotrophic (no chlorophyll), excrete enzymes to digest substrate externally before absorption. No roots, stems, leaves or vascular systems Reproduce asexually, sexually or both Tolerate 0 – 300C+, pH 2 – 9 Tinea Fig 7.6 p. 345 BIF, Ringworm Fig 7.15 p359 BIF Bacteria Procaryotic 0.5 – 5.0µm size Most are free living, many are commensalistic (living in or on organisms), and some are parasites. Varying shapes but all have same basic internal structure (no membrane bound organelles, no true nucleus, cell membrane, cell wall, single strand DNA (nucleoid), ribosomes, enzymes, cytoplasm) Some have capsule (slimy covering layer around cell), flagella, pili, spores (see Fig 3.12 p. 266 BIF) Classified according to: o Staining ability (gram positive or gram negative) o Shape (see figure 3.13 p266 BIF) Spheres Cocci (a single cell) Diplococcic (pairs of cells) Streptococci (chains of cells Staphlococci (clusters of cocci) Tetrads (groups of four) Sarcinae (packets of 8) Rods called bacilli Curves called spirilla Comma shaped called vibrios Reproduce asexually by binary fission, can multiply as short as every 10 minutes i.e. in 24 hours (1440 minutes) one bacteria can multiply (2144) to 2.230072 X 1043 in number! Protozoa Unicellular Mostly microscopic 2.0 - 1000µm size Cell membrane No cell wall Mostly heterotrophic Classified on basis of locomotion (see figure 3.15 p267 & figure 3.16 p268 BIF) o Flagellates e.g. Trypanosoma (African sleeping sickness) o Ciliates e.g. Paramecium o Amoeboids e.g. Amoeba such as amoebic dysentry o Sporozoans non-motile e.g. Plasmodium malaria, cryptosporidium Reproduce asexually, sexually or both Require moist habitat May be: o Free living (no host) o Commensalistic (one benefits, host unharmed) o Mutualistic (both benefit) o Parasitic (one benefits at the expense of the other) Prions Infective agents that cause brain disease and death in mammals e.g. mad cow disease, CreutzfeldtJacob disease (CJD) in humans, scrapie in sheep. Diseases caused by prions are called spongiform diseases because the brain tissue becomes full of holes like a sponge. Are proteins that have been altered from their normal shape, but are chemically the same. A prion can convert other similar but normal proteins into abnormal prion shape (fig 3.8 p263 BIF) Can be passed from one animal to another i.e. are infective. Rickettsias (not in syllabus) Smaller than bacteria 0.2 – 1.0µm long but classified into a different group because they cannot survive outside living cells Procaryotic, gram negative, non-motile, non spore forming type of bacteria Oval-shaped Intracellular parasites Have cell walls Cannot grow outside of living cells Transmitted by arthropods (fleas, ticks, lice) Mycoplasmas (not in syllabus) Smallest cellular creatures ever discovered, 0.1 – 0.2 µm diameter Have only half the amount of DNA of other prokaryotes Are intracellular parasites of animals and plants A genus of bacteria that lack cell walls thus shapes can be irregular Cannot be killed with Penicillin as they do not have a peptidoglycan cell wall (Penicillin kills bacteria by interfering with wall synthesis) Can cause atypical pneumonia and respiratory disease in humans Student Worksheet Summary of some features if microorganisms Microbe Size Structure Method of Reproduction Transmission Comment (µm) classification examples Virus Bacteria Protozoa Fungi Prion TYPE OF PATHOGEN Prions DESCRIPTION EXAMPLE(S) A prion is a special type of protein that causes the degeneration of brain tissue. Scrapie in sheep. Bovine spongiform encephalitis (mad cow disease) and Creutzfeldt – Jakob disease. Viruses Viruses are many times smaller then the smallest bacterial cell. They are borderline between living and non – living. This is due to a lack of metabolism and life characteristics. Viruses rely on the hosts individual cells and nucleic acids to produce more of the same virus. AIDS, chicken pox, genital herpes, cold sores, measles, rubella, glandular fever, hepatitis and influenza. Bacteria Bacteria are disease – causing to the host as they multiply rapidly in blood and tissues. Bacteria also produce toxins which are harmful to the host’s body. Bacteria reproduce by binary fission which can take as little as 10 minutes to as long as 24 hours. Pneumonia, Cholera, legionnaire’s disease, diphtheria and tetanus. Protozoans Protozoan’s are classified by the way they move. African sleeping sickness, Malaria, For example flagellates move by using a whip like Amoebic dysentery and giardiasis. structure called flagellum. Ciliates move by using tiny hairs called cilia, pseudopods use feet like structures which are extensions of the cytoplasm and sporozoa have no structures for motion. Protozoa are mainly found in water. Fungi Fungi can either be caused by saprophytes, the fungi you find on dead plant or animal tissue or parasitic fungi such as athlete’s foot. (Causes flaky, itchy dry skin.) Candidiasis (thrush), athlete’s foot. Macro parasites Macro - parasites can either be external parasites (ectoparasites) or internal parasites (endoparasites). Fascioliasis, Schistosomiasis, hydatid disease, taeniasis, enterobiasis, scabies, house dust (mites). Some common diseases caused by microorganisms Viruses Influenza Common cold Cold sores Genital herpes Chicken pox Shingles Small pox (eradicated) German measles (rubella) Measles Mumps Glandular fever Hepatitis A, B, C Poliomyelitis Ross river fever Encephalitis Viral meningitis Viral conjunctivitis Warts Yellow fever AIDs Domestic animals Foot & mouth disease Blue tongue Rinderpest Distemper Rabies Bacteria Diphtheria Whooping cough Tetanus Tuberculosis (TB) Syphilis Gonorrhoea Cholera Legionnaires disease Salmonella (food pois.) Botulism (food pois.) Gas gangrene Gastroenteritis Rheumatic fever Scarlet fever Typhoid fever Bacterial meningitis Bacterial conjunctivitis Golden staph (food pois) Bubonic plague (bacillis) Brucellosis Dysentery (bacterial) Pneumonia (bacterial) Erysipelas Impetigo Leprosy Campylobacter Shigella Yaws Yersinia Tonsillitis Anthrax Fungi Tinea Candidiases (Thrush) Ringworm Dandruff Prions Mad cow disease, Creutzfeldt-Jacob disease (CJD) in humans Scrapie in sheep. Protozoa Malaria African sleeping sickness Amoebic dysentery Chagas disease Giardia (flagellate diarrhoea) Cryptosporidium Cyclospora Leishmaniasis Toxoplasmosis Rickettsias & mycoplasmas Trachoma Venereal disease Forms of pneumonia Typhus Table 1: Diseases caused by viruses Viral Diseases AIDS (acquired immune deficiency syndrome) chicken pox cold sores genital herpes measles rubella (German measles) Cause HIV (human immune deficiency virus) herpes varicellazoster virus herpes simplex type 1 virus herpes simplex type 2 virus morbilli virus rubella virus Transmission by direct contact of body fluids, e.g. through sexual contact or blood transfusion or dirty needles used by drug addicts air; skin contact; the placenta via the foetus; indirect contact (bedding etc.) direct skin contact; indirect contact through bed linen, towels etc. direct contact during sexual intercourse or at birth in air droplets glandular fever EpsteinBarr virus direct contact (touching); indirect contact (for example, bedding); in air (coughing, sneezing); via placenta to foetus direct contact including saliva infective hepatitis (hepatitis A) hepatitis A virus contaminated food or water hepatitis B hepatitis B virus influenza influenza virus — there is a family of these viruses sexual intercourse; contaminated injection needles in air from sneezing, coughing or breathing Symptoms fatigue, loss of appetite and weight; diarrhoea; infections and other diseases such as Kaposi’s sarcoma (a skin cancer) pink spots that become itchy, blister and burst Treatment and control treatment AZT and other drugs (not curative) control change of lifestyle among promiscuous individuals and drug addicts fatigue; headaches; limb pains treatment no drugs available; adequate rest for patient control isolation of patients treatment no drugs available; adequate rest for patient control isolate patient; vaccine treatment antibodies are produced to confer natural immunity, calamine lotion reduces the itchiness control isolation of the patient sores on mouth or lips treatment use of mouth-washes; that form blisters ointments (anti-viral) control avoidance of direct contact during attacks, vaccine (a recent development) sores on the genital treatment the drug acyclovir will reduce area the severity of attacks control avoidance, e.g. sexual contact during attacks; good diet and rest; vaccine (recently developed) rash on body; nausea; treatment no drugs available; adequate headache; fever rest for patient control vaccination sore throat; fever; treatment fluids, analgesics, to relieve headache; rash (rash or reduce pain less severe than control isolation of patients; measles) immunisation especially of teenage girls fever alternated with shivering; pains in limbs; jaundice (yellowing of skin); fatigue; headache nausea; fatigue; jaundice headache; pain in limbs; respiratory tract infection; fever treatment no drugs available control clean injection needles; screen blood donors; vaccine treatment rest; analgesics control precautions by infected people when sneezing and coughing; vaccines are effective against some strains Table 2: Diseases caused by bacteria Disease Cause pneumonia Diplococcus pneumoniae; or Streptococcus lung congestion pneumoniae (bacteria) Transmission in air from sneezing and coughing Symptoms f ever; coughing lung congestion Treatment and control treatment penicillin and other antibiotics control isolation of patients cholera Vibrio cholera (bacterium) in water contaminated with sewage; in contaminated food severe diarrhoea and dehydration treatment replacement of water and salts; drugs such as tetracycline and chloramphenicol control purification of water; food; good sewerage system; vaccination legionnaires’ disease Legionella Through airconditioning systems Fever, coughing lung congestion Treatment antibiotics rifampicin and erythromycin Control regular sterilisation of airconditioning systems; isolation of patients diphtheria Corynebacterium diptheriae Direct or indirect contact Spots on throat and tonsils; headache; vomiting Treatment: drugs and antibiotics Control: isolation of patients; immunisation especially of children Table 3: Diseases caused by protozoans Disease Cause African Trypanosoma species sleeping (protozoan) sickness malaria Plasmodium species (protozoan) amoebic dysentery Entamoeba histolytica (protozoan) giardiasis Giardia lamblia (protozoan) Transmission intermediate host is the tsetse fly which transfers the pathogen to blood when it bites humans by the vector the Anopheles mosquito Symptoms fever, headache; enlarged lymph glands; drowsiness; coma Treatment and control treatment drugs control eradicate tsetse fly; protection of humans against tsetse flies; early diagnosis and treatment; perhaps a vaccine in the future fever alternating with shivering; anaemia unhygienic food and water supplies; uncooked food unhygienic food and water supplies; uncooked food diarrhoea; nausea; vomiting; fever treatment chloroquine and other drugs control elimination of mosquitoes’ breeding places— usually ponds and lakes; eradication of mosquitoes; use of preventive drugs in humans; precautions such as clothing, mosquito nets treatment drugs e.g. antibiotics, including sulfa drugs control eradication of flies that spread the disease; hygiene in food handling treatment anti-protozoan drugs control hygiene in food handling; proper treatment of drinking water Table 4: Diseases caused by fungi Disease Cause Transmission candidiasis yeast (Candida C. albicans occurs (‘thrush’) albicans) naturally in human tissues; if the competition from other natural microbes is upset it can cause symptoms; it can be transmitted from a vaginal infection in the mother to the baby at birth athletes’ foot fungus (Tinea direct contact pedis) (touching); indirect contact through use of towels, showers, swimming pools diarrhoea; nausea; vomiting; bloating; flatulence Symptoms white patches in mouth or itchiness in the vaginal area or inflamed skin Treatment and control treatment specific anti-fungal chemicals control keeping susceptible areas of the body clean and dry; altering whatever causes the imbalance e.g. oral contraceptives itching and blisters between toes; skin peels and cracks; secondary bacterial infections are possible in the cracks treatment anti-fungal chemicals taken orally or applied externally control care in drying between the toes after bathing; infected individuals should avoid sharing towels etc. Table 5: Some diseases caused by macroscopic parasites Disease Cause Transmission facioliasis Fasciola hepatica (liver through plants (sheep liver fluke) or grass in damp disease) areas that contain the cysts Symptoms haemorrhaging of liver tissue; bile duct blockage; abdominal pain; anaemia schistosomiasis Schistosoma (blood (blood fluke fluke)— there are a disease, few different species sometimes called bilharzia) from water supplies that are contaminated with the cysts loss of weight; diarrhoea; anaemia; abdominal pain; itchy skin and rash hydatid disease Echinococcus granulosus (tapeworm) by touching infected dog’s hair or faeces and transferring the eggs to the mouth taeniasis (tapeworm disease) Taenia solium (pork tapeworm) or Taenia saginata (beef tapeworm) by undercooked, infected pork or beef anaemia; pressure on internal organs; severe pain and severe shock if the cysts burst; death in severe cases loss of weight; possibly abdominal pain enterobiasis (threadworm disease) Enterobiasis vermicularis (threadworm) from bed linen or other items that contain the eggs restlessness at night; anal itchiness scabies Sarcoptes scabei (itch mite) severe itching house dust mite asthma Dermatophagoides usually by indirect contact pteronyssinus—the through bed linen, carpets, house dust mite house dust by direct skin contact from infected people or indirect contact through bed linen allergic reaction; coughing; sneezing bronchial congestion treatment some drugs used in treating allergies are useful control regular vacuuming, airing bedding; use of anti-allergen spray Treatment and control treatment the drug bithionol control eradication of fresh water snails; proper water and sewerage systems; clean water troughs for sheep; care by humans with wet grass or plants treatment there are drugs that are effective if the disease is diagnosed early control proper water and sewerage systems; treatment of infected people; eradication of fresh water snails treatment there are no known drugs to cure this disease control worm treatment for dogs; proper hygiene when handling dogs; thorough cooking of meat for dog food; early treatment and prevention of the disease in cattle and pigs treatment the drug miclosamide control thorough cooking of pork and beef; early treatment and prevention in cattle and pigs; strict abattoir inspection of meat treatment combantrin (taken orally); family treatment recommended control strict hygiene with bed linen, towels etc. treatment external application of chemical to the skin (family treatment recommended) control strict hygiene with bed linen etc.; early treatment of infection Treatment some drugs used in treating allergies are useful Control regular vacuuming, airing bedding; use anti-allergen spray Identify the role of antibiotics in the management of infectious disease. Things to consider: - What does identify mean? - What are antibiotics and what are their uses? The chief role of antibiotics is to destroy or inhibit the growth of bacteria. They are special types of chemicals which act selectively on invading pathogens without affecting the host. They only work on bacterial infections, not viruses. Different types of antibiotics target different types of bacteria. ‘Broad - Spectrum,’ antibiotics act on a large range of bacteria while ‘narrow – spectrum,’ antibiotics act on a small range of bacteria. Antibiotics work at a cellular level. They interfere with the development of the bacteria by either damaging or destroying the bacterial cell. For example penicillin has a special ring shaped molecule which gives it bactericidal properties. This affects the formation of the bacteria’s cell wall. Gather and process information to trace the historical development of our understanding of the cause and prevention of malaria. HISTORY SHOWING THE DEVELOPMENT OF OUR UNDERSTANDING OF MALARIA Early 19th Century: Cause of malaria unknown. Antimalarial properties found on cinchona tree. (Quinine) 1880: First malaria parasite seen in blood by Charles Laveran. End of the 19th Century: Connection between mosquito and malaria parasite made by Ronald Ross. Found that mosquitoes carrying the disease infected volunteers who were bitten by the mosquitoes. 1898: Ross describes the life cycle of the malaria parasite. The Beginning of the 20th Century: Chemical nature of quinine determined which led to the synthesis of drugs. Most effective was chloroquin. Continued use of drugs led to resistance in the malarial parasite. 1940’s: Evidence to suggest that people with one gene for sickle – cell anaemia are more resistant to malaria due to shape of their red – blood cells. 1990’s – 2000: Continued research to produce a vaccine. LIFECYCLE OF MALARIAL PARASITE Firstly a female anopheles mosquito bites a human using their feeding tube or stylet. On the stylet are many sporozoites. These sporozoites make there way into the bloodstream. The sporozoites need to develop. This is achieved if the sporozoites make it to the liver. Once the sporozoites make it to the liver they are supplied with nutrients to grow and divide. This is known as asexual reproduction and each sporozoite produces 16 smaller spherical merozoites. They are released into the blood plasma where the merozoites invade red blood cells. The red blood cells become so full of merozoites that they burst causing waste product to enter the bloodstream. This causes symptoms such as a fever. Some merozoites develop into female and male gametocytes. If a mosquito feeds on a human suffering from malaria these gametocytes maybe transferred into the mosquito. These gametocytes become gametes in gametes in the mosquito, they replicate and eventually produce sporozoites, and so the cycle continues. PREVENTION OF MALARIA Anti – Malarial drugs administered before visiting endemic areas. Prevention aims to keep the disease at a minimum. Breeding grounds of the vector maybe destroyed. Draining of swamps and using insecticides. Development of vaccines. Genetic engineering of mosquitoes to develop individuals who will resist the parasite. These are some of the measures to prevent the spread of malaria. Process information from secondary sources to discuss problems relating to antibiotic resistance. Things to consider: - What does process mean? - Always refer to antibiotic resistance. Identify defence barriers to prevent entry of pathogens in humans. - Skin - Mucous membranes - Cilia - Chemical Barriers - Other Body Secretions Things to consider: - What does identify mean? - Be succinct; write briefly about each defence barrier. The body has numerous defence barriers which prevent the entry of pathogens into the body. They are as follows: Skin - Has a tough coating Contains chemicals that destroy invading organisms Certain bacteria on skin destroy incoming pathogens Dry, pathogens rely on damp areas to grow Mucous membranes - Production of mucus carries pathogens out of the body - Nasal passage traps and secretes pathogens - Respiratory system produces mucus. Reflex actions such as coughing eject the pathogen from the body - Urogenital surfaces can produce mucus to excrete any invading pathogens Cilia - Found in the nasal, throat, ear and respiratory system. Consists of tiny hairs With the help of mucus trap pathogens and secrete them out of the body Chemical Barriers - Stomach acid provides a lethal environment for pathogens - Saliva and tears contain lysosomes which destroy invading pathogens Other Body Secretions - Other body secretions include; bacteria in intestines, wax in ears, urine and sweat. These all prevent invading pathogens. Health and Disease HSC Core unit 3 The Search for Better Health (Supplementary notes compiled by IR 1/5/11) Pattern of Infectious Disease: 1) 2) 3) 4) 5) Entry into body Incubation Appearance of symptoms Crisis Convalescence - the period from entry of the pathogen until the symptoms appear - nausea, fever, etc … - recovery or death - the symptoms disappear and the patient recovers Treatment: Treat symptoms only, whilst allowing the body to produce its own antibodies to overcome the infection Medicine to attack microorganisms e.g. antibiotics or sulfoamide drugs for bacterial infections Aid the body’s natural defence mechanisms by injecting antibodies or antitoxins so as to render harmless either the pathogen or its toxins, e.g. antitoxin to treat diphtheria. Control: Reduce source of infection (isolate, quarantine...) Reduce transmission of infection (interrupt life cycle of pathogens) Protect susceptible people (immunisation, vaccinate to help body defences Education to increase awareness Provide clean water, clean food and effective sewage treatment Sterilise or disinfect contaminated articles Personal hygeine Screening of possible carriers of disease Identify antigens as molecules that trigger the immune response. Things to consider: - What does identify mean? - What is an antigen? - What is an immune response? An antigen is a molecule that causes an immune response within the body. Antigens are carried on pathogens. When the pathogen enters the body, the body recognises the antigen and begins to produce an immune response. Explain why organ transplants should trigger an immune response. Things to consider: - What does explain mean? - Relate answer to antigens - What is an immune response? The body immune response is due to the invasion of foreign material. In organ transplants diseased tissue is replaced by healthy tissue such as kidney’s, liver, heart, lungs and bone marrow. These healthy tissues are foreign to the body and contain certain proteins (antigens) that are recognised as foreign. The patient’s body then stimulates the production of antibodies that attack and possibly destroy the new tissue. To prevent the rejection of the organ transplant the patient’s immune system is suppressed. This is due to the fact that blood drains into the recipient’s circulation; the body recognises the foreign tissue cells and produces antibodies in response. Rejection is reduced by matching the transplanted tissues proteins as closely as possible with the recipient’s proteins. Anti – rejection drugs are also administered. These suppress the immune response and prevent rejection of the organs. e.g. Antilymphocyte Globulin (ALG) Identify defence adaptation including: - Inflammation response - Phagocytosis - Lymph System - Cell death to seal of pathogens Things to consider: - What does identify mean? - Consider a suitable method of answering this question such as a table. DEFENCE ADAPTATION DESCRIPTION Inflammation response When body tissue has been invaded by a pathogen, the area of infection may become hot, red, swollen and painful. The blood circulation to that area is increased and the blood vessels dilate leaking more blood in the infected area. This response helps confine the pathogen, while the increase in blood volume leads to an increase of white blood cells which help destroy the invading pathogen. This process also allows for the quick removal of dead cells as well as the removal of toxins so that normal body function can occur. (Histamines and prostaglandins are chemicals which mediate the inflammation response.) Phagocytosis Phagocytes are a special type of white blood cell which actively moves from the blood where they ingest and destroy any foreign materials such as pathogens. This is known as phagocytosis. In acute inflammation which only lasts for a few hours or days, the main phagocytes used are called neutrophils. In chronic inflammation which lasts for weeks or months the main phagocyte used are called macrophages. This defence adaptation allows for the efficient decomposition and destruction of invading pathogens. Lymph system The lymph system is a network similar to that of our own circulatory system. This system transports a special fluid known as lymph similar to that of extracellular fluid. Lymph is transported away from the cells towards the heart. At various points around the body are smaller vessels called lymph nodes. Lymph nodes are responsible for the production of lymphocytes. These lymphocytes are added to the lymph as it flows through the body. Lymph nodes are also responsible for engulfing and destroying bacteria and other foreign material. Lymph nodes become swollen or inflamed when fighting off infection due to the toxins released by the bacteria. Lymphocytes are white blood cells the main two types being T cells and B cells. Cell death to seal Sometimes the body will seal of a group of pathogens to form a cyst. Part of this cyst of pathogens will involve a group of cells. These cells are sacrificed so that the pathogen can be destroyed. Gather, process and present information from secondary sources to show how a named disease results from an imbalance of microflora in humans. Things to consider: - What do gather, process and present information mean? - Ensure you used a named disease - What is microflora? - Page 282 Microflora in humans are microbes which live in the human body without causing disease. This is a symbiotic relationship whereby the digested food is processed by the microbe in return for essential vitamins. An example of a named disease which results in an imbalance of microflora in humans is candidiasis. The following information outlines how the imbalance of Candida affects a human: - Candidiasis is the over population of the yeast/fungus Candida albicans. - This yeast like organism is highly present in our mucous membranes. - Candida albicans is controlled by lactobacilli and bifidobacteria largely found in the intestinal tract. - When lactobacilli and bifidobacteria numbers drop there is a sudden increase in the numbers of Candida in the gastrointestinal tract. - Candida then changes from a yeast like form to a fungal form. This fungal form has root like structures which enter the lining of the gastrointestinal tract. - This weakens the gastrointestinal tract and substances usually confined to the gastrointestinal tract leak into the bloodstream. - Partly digested proteins enter the bloodstream which results in the production of antibodies from the immune system. - This usually results in severe allergic reactions including cerebral (brain) allergies. - Rapidly growing populations of Candida can almost relocate anywhere in the body causing numerous amounts of problems. In children an excess of Candida usually results in the common disease known as thrush. It is evident that through a slight imbalance in microflora in humans may result in the emergence of disease. (http://www.wadsworth.org/databank/hirez/wongp1.gif) MICROGRAPH OF CANDIDA ALBICANS Identify the components of the immune response: - antibodies - T cells - B cells Things to consider: - What does identify mean? - Write brief descriptions of the above components of the immune response. - Page 291 COMPONENTS OF IMMUNE RESPONSE ANTIBODIES DESCRIPTION Antibodies also known as immunoglobulins are produced in the lymph nodes by B cells in response to a specific antigen. Antibodies are special proteins which circulate in the blood plasma and combine with B cells to destroy antigens. This is called antibody – mediated immunity. T CELLS T cells are a type of lymphocyte which form in the bone marrow and mature in the thymus gland. They remain inactive while travelling around the body until they come into contact with an antigen. The T cell binds onto the antigen and makes copies of itself. T cells control the cell – mediated response whereby various types of T cells destroy the antigen or foreign cell. B CELLS B cells develop and mature in the bone marrow. B cells are activated in the blood when there is a presence of an antigen. Activated B cells clone themselves into either plasma cells which send antibodies into the blood or into memory cells. Describe and explain the immune response in the human body in terms of: - interaction between B and T lymphocytes - the mechanisms that allow interaction between B and T lymphocytes - the range of T lymphocyte types and the difference in their roles Things to consider: - What does describe and explain mean? - Identify the best way to answer this question. - Understand what you are writing before you write it down. The immune system and the components within the immune system are constantly interacting with one another to provide the best defence against invading organisms. One such interaction is the interaction between B and T lymphocytes (cells). T cells and B cells work together by attacking the same antigen. Helper T cells, a special type of T cell, stimulate the cloning of T cells and B cells to help destroy invading pathogens. T cells can also trigger an immune response in B cells by secreting a substance known as a cytokine. This special protein signals other cells to trigger an immune response. Although B cells and T cells are constantly interacting there are certain mechanisms in place which prevent these cells from attacking one another. For example if a B cell is expressing an antigen on its membrane it is not destroyed by another T cell. The body has adapted a mechanism whereby cells are capable of recognising “self” molecules. This prevents the unnecessary destruction of the bodies own cells. There are a range of T cells that all have a specialised function in preventing the spread of disease in the human body. Cytotoxic T cells destroy cells that contain foreign antigens. These non – self molecules such as bacteria are destroyed by cytotoxic T cells and are removed from the body. Helper T cells secrete a chemical known as interleukin which regulates the function of T and B cells. Suppressor T cells regulate the activity of B and T cells. For example cytotoxic T cells are suppressed once they have carried out their role. Outline the way in which vaccinations prevent infection. Things to consider: - What does outline mean? - What are vaccinations? - Be succinct The process of vaccination also known as immunisation is the process of making people resistant to an infection caused by a pathogen. Vaccines can be administered in two ways, one via injection the other via an oral dose. Vaccines are a preparation of a weakened or dead infective micro – organism. This dose is injected into the patient with the intention of eliciting an immune response to the disease without causing any symptoms. Some vaccines are only administered once as the patient will have immunity for life, for example the measles vaccine. Other types of vaccines require a “booster,” vaccine which is administered 5 – 10 years after the original vaccination. This increases the immunity against the disease, a type of this vaccination is tetanus. Overall vaccinations prevent disease as they enable our body to register an immune response and build up memory cells which in turn will fight the disease if the person is ever exposed to that disease. Outline the reasons for the suppression of the immune response in organ transplant patients. Things to consider: - What does outline mean? - Relate answer to the immune system. - Understand what the question is asking before you answer. Suppression of the immune response is a necessity after an organ transplant in order for the new organ not to be rejected by the recipient. As some blood from the donated organ enters the blood stream of the recipient, the body recognises the foreign tissue cells and begins to produce antibodies in response. A number of cells such as cytotoxic T cells are produced which could affect the implanted tissue. The rejection of this organ is reduced by closely matching the donor organs proteins to the recipient’s proteins. By doing this it allows the recipient a higher chance of accepting the organ. The immune system is also suppressed after an organ transplant. Antilymphocyte globulin (ALG) is a drug that suppresses the immune response. This drug allows the recipient a greater chance of accepting the organ rather then destroying it. A balance between suppressive drugs and monitoring increases the chances of the organ transplant being a success. Identify and describe the main features of epidemiology using lung cancer as an example. Things to consider: - What does identify and describe mean? - What is epidemiology? - Be succinct. Epidemiology is the study of disease that affects many people. These types of studies describe the patterns and causes of certain diseases within a population. The diseases studied can be infectious diseases such as influenza and non – infectious diseases mainly caused by lifestyle and environmental factors. Epidemiological studies have been able to establish links between smoking and lung cancer. With this knowledge government agencies can take preventative measures such as warnings on smoking packets or advertisements which show the adverse effects smoking has on the human body. It is through epidemiology scientists have been able to draw links between disease and certain underlying factors which in turn gives rise to treatment, control and prevention. Identify causes of non – infectious disease using an example from each of the following categories: - inherited disease - nutritional deficiencies - environmental diseases Non – infectious disease is caused by many underlying factors. These factors include the malfunction of the physiology, metabolism or structures of the body. These malfunctions lead to the deprivation and disease for the human body. Non – infectious disease falls into three main categories. Firstly inherited disease is a non – infectious disease passed on from generation to generation through the genetic code of the family. An example of an inherited disease is Down syndrome. Secondly nutritional deficiencies cause non – infectious disease by either malnutrition (nutrients totally unbalanced) or under - nutrition (not enough food). Some examples of nutritional deficiencies include anorexia nervosa, kwashiorkor and Aboriginal nutritional diseases. Thirdly environmental factors cause non – infectious disease by polluting the body with unnecessary and often poisonous substances. Such substances include alcohol, tobacco, drugs and heavy metals. These poisons can cause disease such as heavy metal poisoning, cirrhosis of the liver or lung cancer. Gather, process and analyse information to identify the cause and effect relationship of smoking and lung cancer. Ever since the introduction of tobacco and smoking, there has always been the conception that smoking causes lung cancer. This was thought to be true as early as the 1920’s. Subsequently epidemiological studies were performed between the 1930’s – 1960’s to test whether or not smoking was the cause of lung cancer. Two significant studies were produced by Doll (1947) and Hill (1951). Doll used a case study report by comparing two different groups of people. The first group of people all had lung cancer while the other group had various diseases. Both of these groups were asked about their smoking habits. What Doll found was that a large percentage of the lung cancer patients were smokers while the control group a smaller percentage were smokers and it was quite possible that their illness was caused by smoking as well. Doll’s results were as follows: CASES TEST GROUP CONTROL GROUP Smokers 1350 1296 Non – Smokers 7 61 Total 1357 1357 Hill’s cohort study involved a number of doctors across Great Britain. The study involved the doctors answering a number of questions on their smoking habits. Those doctors who were smokers were part of the smoking group, while those doctors who did not smoke were part of the control group. Both groups were followed over a 10 year period. During this period 133 people died. Of those 130 of them were smokers. The results were as follows: DAILY NUMBER OF CIGARETTES SMOKED 0 1 – 14 15 – 24 25+ TOTAL DEATHS FROM LUNG CANCER 3 22 54 57 133 The above table indicates that the greater the number of cigarettes smoked a day the greater chance of death by lung cancer. Subsequently many more epidemiological studies have taken place to illustrate the cause and effect relationship between smoking and lung cancer. This has lead to a greater awareness of the risk factors involved with smoking. Pages 309 to 312 contain further information about smoking and lung cancer. Identify data sources, plan and perform a first – hand investigation or gather information from secondary sources to analyse and present information about the occurrence, symptoms, cause, treatment/management of a named non – infectious disease. (Page 318) Things to consider: - This will be a secondary source task. What does gather, analyse and present mean? - How will you present your findings? - Choose one disease and be succinct. DOWN SYNDROME OCCURRENCE The occurrence of down syndrome increases with the age of the mother. The general rule of thumb is that the chance of having a baby with down syndrome increases with maternal age. However the chance of having two babies with down syndrome is less then 1%. According to Wikipedia down syndrome occurs in 1 in 800 – 1000 births however there are many underlying factors which affect this result. SYMPTOMS Symptoms of down syndrome include; mild to sever mental retardation, small flat nose, skin folds at the eye corners, appearance of slanted eyes, protruding tongue, small ears, shorter neck, arms and legs, increase chance of eye defects (often wear glasses) and an increase chance of heart defects. CAUSE There are 3 types of down syndrome. Their causes are outlined below: Trisomy 21 – occurs in about 92% of down syndrome cases. Trisomy 21 is caused by the presence of an extra chromosome 21 in all cells. Mosaic trisomy 21 – occurs in about 2 – 4% of down syndrome cases. Mosaic trisomy 21 is caused by the presence of an extra chromosome in some of the babies cells. Translocation trisomy 21 – occurs in about 3 – 4% of down syndrome cases. Translocation trisomy 21 is caused by chromosome 21 getting stuck or translocated during conception or growth of the baby during pregnancy. This results in the baby having 46 chromosomes but expressing down syndrome symptoms. TREATMENT/MANAGEMENT There is no cure as such for down syndrome. However there are special education programs which can assist children. Many children with down syndrome can become independent and live normal lives. Explain how one of the following strategies has controlled and/or prevented disease: - public health programs - pesticides - genetic engineering to produce disease – resistant plants and animals (Page 332 – 333) Things to consider: - What does explain mean? - You only have to choose ONE. Some knowledge on all three could be beneficial (if you have time). - Be succinct. Through genetic engineering scientists have been able to produce disease resistant plants and animals. By increasing our knowledge of certain plants and livestock, and their genetic make – up, humans have been able to increase food supplies. Genetic engineering is a relatively new study and the full potential of this technique has not been realised. For example Australian scientists have produced a genetically modified pea that is resistant to the pea weevil. The pea weevil consumes large amounts of crops every year in Australia. The gene that confers resistance to the pea weevil was extracted from the common kidney bean. This gene was spliced into the pea crops. The result was that the gene produces a certain protein that cannot be broken down by the larvae and hence the larvae die out. A simple animal example is humans. In medicine scientists have genetically engineered insulin using recombinant DNA to help control diabetes. Perform an investigation to examine plant shoots and leaves and gather first – hand information of evidence of pathogens and insect pests. Things to consider: - What are insect pests? (Rose bush cuttings will be acquired. Look for tiny insects known as aphids. These insects suck the sap out of the rose bush.) - What are pathogens? (Look for discolouration of leaves or bulges/growths on leaves and stems - Refer to page 328 for experimental procedure. Gather your results and write your Conclusion to your experiment. ASSESSMENT DOT POINTS The following dot points will be covered in your assessment task 4. I have not written any responses to these dot points. However, if you need assistance with these please notify myself as soon as possible. 1. Identify data sources, gather process and analyse information from secondary sources to describe one named infectious disease in terms of its: Cause (name and type of pathogen) Historical developments in our understanding of the disease Life cycle and / or special characteristics of this pathogen Transmission Host Response Major Symptoms Treatment Prevention Control 2. Process, analyse and present information from secondary sources to evaluate the effectiveness of vaccination programs in preventing the spread and occurrence of once common diseases, including smallpox, diphtheria and polio. 3. Discuss the role of quarantine in preventing the spread of disease and plants and animals into Australia or across regions of Australia. 4. Process and analyse information from secondary sources to evaluate the effectiveness of quarantine in preventing the spread of plant and animal disease into Australia or across regions of Australia. 5. Gather and process information and use available evidence to discuss the changing methods of dealing with plant and animal diseases, including the shift in emphasis from treatment and control to management or prevention of disease.