eddiethe search for better health.docx

8/14/2019 EddieThe Search For Better Health.docx

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The Search For Better Health

What is a healthy organism?

Discuss the difficulties of defining the terms health and disease

Difficulty to define health:

World health organisation:

Astate of complete physical, mental and social well-being and not merely the absence of disease or infirmity

Too broad and if taken literally, it is very difficult to achieve a healthy status Concept of health is constantly changing and is relative to others and ourselves

e.g. person who has diabetes may be doing the best she can and feeling healthy

Term is used in many different ways. For e.g. in every day conversationDifficulty to define disease:

Any condition that adversely affects the normal functioning of any part of a living thing

Quite broad and impreciseconditions that would not normally be classed as disease could bebroken arm normal functioning may be at different levels for different individuals. e.g. absent mindedness in elderly may

be a normal facet of aging

Terms used by general public in everyday conversationOutline how the function of genes, mitosis, cell differentiation and specialisation assist in

the maintenance of health

GenesContains coded information for protein.

Genes are responsible for controlling the rate of cell division; thus faulty control genes can lead to cancer. DNA repair

genes code for proteins responsible for stopping cell cycle while other proteins remove damaged regions of DNA and

replace them with new correct sequence. Proto oncogenescode for proteins that stimulate cell growth and mitosis.

Tumour suppressor genescode for proteins that slow down or stop cell growth and mitosis

MitosisProcess of cell division by which identical body cells are produced. This is often a response to disease because

damaged cells and tissue need to be replaced. It also normally occurs to replace old or damaged cells

Cell differentiationProcess by which a cell changes its structures and function as it develops

Cell specialisationfunctioning of a cell to perform a particular role

Cells are differentiated and specialised to perform roles that maintain and repair tissue and also allow the whole body to

survive.

Use available evidence to analyse the links between gene expression and maintenance and

repair of body tissues

Gene expression occurs when a gene is switched on and the DNA code is converted into polypeptides that control the

structures and functions of a cell


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Mutations occur when a gene is altered and it can no longer code for the correct polypeptide. This puts the health of the

individual at risk, as a particular chemical reaction may be unable to occur, resulting in a particular disease. Therefore

correct gene expression is therefore necessary for ongoing maintenance and repair or tissues.

For e.g. PTEN gene is a tumour suppressor gene that limits amount of cell division and encourages cell death. BRCA1 is a

tumour suppressor gene responsible for coding for proteins involved in repair of PTEN gene. Mutations in the BRCA1

gene mean PTEN gene would not be repaired, resulting in lack of control of cell cycle and runaway cell division leading to

formation of tumours.


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Over 3000 years ago the Chinese and Hebrews were advocating cleanliness in food,

water and personal hygiene

Distinguish between infectious and non infectious disease

An infectious disease is a disease that is caused by an organism called pathogens, which are transmitted from one

organism to another or from an environment to an organism.

A non infectious disease is a disease that is not caused by a pathogenincludes inherited, environmental and nutritionadiseases

Explain why cleanliness in food, water and personal hygiene practices assist in control of

disease

Intake of food and water provide an easy way for microorganisms to enter our bodies. Therefore minimising the

number of such organisms in our food and water reduces the risk of infection

Food:

Store food in dry places or by freezing to avoid/inhibit growth of bacteria Clean utensils before using for different foods All chicken and mince based foods cooked thoroughlykill bacteria Foods covered before storageprotect from contamination Hairs and skin lesions covered in food shops

Water:

Government has established standards and water is tested daily to ensure standards are met If water quality is unsure of, boil the water and allow it to cool

Personal hygiene:

Hands always washed before preparing and eating food and after going to the toiletprevents spread ofpathogens

Body and hair should be regularly washed and teeth cleaned to prevent build up of pathogens Cough or sneeze into handkerchief

Community hygiene:

Sewage and garbage disposal- reduces risk of pathogen number increasing Sterilisation and disinfection of equipment in hospitals

City planningreduce overcrowding

Identify the conditions under which an organism is described as a pathogen

Pathogenorganism or infective agent that causes disease

Able to survive outside a host Transfer through direct or indirect means or by a vector (mosquito)


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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

Primary treatment:

FlocculationChemicals e.g. polyelectrolytes are added to the water to neutrialise electrical charges of fineparticles in water allowing particles to come closer, stick together to form large clumps (flocs). The clumps are

then easier to filter or settle from water CoagulationAluminum sulfate is added to help sink flocs and make sedimentation faster Sedimentationwater flows into a tank called a sedimentation basin where gravity causes flocs/particles to

settle down the bottom to form sludge

Sludge processingsolids and liquids are collected from the settling tanksSecondary treatment:

Filtrationwater is filtered e.g. by through sand beds so that particulate matter that may harbor pathogens areremoved

Backwashingoccurs when clean water is pumped backwards through the filters to flush them clean of sludgeTertiary treatment:

Chlorinationfew part per million of chlorine is injected into water to kill most remaining microbes Fluoridationsodium fluorosilicate is added to water (reduce tooth decay) Other ways to disinfect waterheat, UV light, Ozone gas injected into water

This treatment of water kills most pathogens, reducing the risk of infection from these pathogens

Identify data sources, plan and choose equipment or resources to perform a first hand

investigation to identify microbes in food or in waterMicroorganisms in air:

Workbench area was sterilised by swabbing with methylated spirits Four sterilised petri dishes that contained nutrient agar was collected One plate was unexposed, sealed with sticky tape and labeled as the control Three locations were selected where each plate was exposed to the air of the location for 15 minutes, then

sealed with sticky tape and labeled with the location/date

Plates were incubated for 37 days at 40Microorganisms in water:

Workbench area was sterilised by swabbing with methylated spirits Four sterilised petri dishes that contained nutrient agar was collected One plate was unexposed, sealed with sticky tape and labeled as the control 0.5ml of each water sample was placed onto the agar plate using a sterile pipette, lid was closed and dish gently

rocked so that the water sample spread evenly over the entire plate

All dishes were sealed with sticky tape and labeled and then incubated for 3 7 days at 40Microorganisms in food:


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Pathogen Description Example of disease

Prions Protein that has been altered

from its normal structure and

can then alter other proteins to

develop more prions, so that the

change spreads like a chain

reaction.

Kuru

Viruses Consist of DNA or RNA enclosed

in protein, live inside living cells.They are so small that they

cannot be seen with a light

microscope.

Influenza

Bacteria Single celled prokaryotic

organismhave cell wall but no

membrane bound organelles

Cholera

Protozoans Single celled eukaryotic

organismshave cell membrane

but no cell wall and possess

membrane bound nuclease and

membrane bound organelles

Malaria

Fungi Eucaryotic organisms that

possess cell walldo not contain

chlorophyll and not capable of

producing own food. Can be

unicellular or multicellular

Thrush

Macro parasites Parasites/ organisms that are

visible to the naked eye Flatworms Fleas

Identify the role of antibiotics in the management of infectious disease

Antibiotics are chemicals with the role of destroying or inhibiting the growth of the bacteria that cause disease.

In 1928, Alexander Flemming discovered the first antibiotic when he observed the effect of Penicillium mould on the

growth of bacterial colonies on an agar plate. Penicillin became available for medical use in 1941.

Some antibiotics accumulate in the cells of the bacteria and prevent them from forming a new cell wall whendividing e.g. penicillin

Some antibiotics destroy the cell membrane, thus effectively destroying the bacteria, for e.g. amphotericin Some antibiotics interfere with protein synthesis so that bacteria are unable to make essential compounds,

resulting in death of the celle.g. erythromycin

Broad spectrum antibiotics such as sulfonamides act on a wide range of bacteria and are used when the identity of the

bacteria causing the infection is unknown while narrowspectrum antibiotics such as penicillin act on only one or two

types of bacteria.


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Identify data sources, gather process and analyse information from secondary sources to

describe one named infectious disease in terms of its:

- Cause- Transmission- Host response- Major symptoms- Treatment- Prevention- Control

Influenza:

Cause:

Caused by infection with influenza virusesinfluenza A and B (virus) being the two main types They are viruses that infect humans, containing RNA surrounded by a protein coat

Transmission:

Direct contactthe viral particles inhaled through nose and mouth in droplets that have been exhaled by aninfected person when they sneeze or cough

Indirect contactinfected person touches respiratory tract and then something else such as a handrail andwhen a healthy person touches it soon afterwards and then places hand on their nose or mouth

Host response:

Immune system is initiatedproduces antibodies and other immune response cells specific for the particularstrain of influenza virus that has infected the body.

Immune system is responsible for destroying the viral particles that have invaded the bodyMajor symptoms:

Fever Headache Inflammation of the upper respiratory tract Sore throat Muscle pain (myalgia) Nasal catarrh (inflammation of the mucous membrane) Sneezing and coughing

Treatment:

No treatment that will cure it


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Main method of treatment is to relieve symptoms by getting plenty of bed rest and drinking extra fluids. Bedrest allows body to fight disease and then recover.

Aspirin and paracetamol can be given to help alleviate headaches, sore throat and muscle pain and to reducefever

Prevention:

Use of influenza vaccines that are produced each year and are derived from the influenza A and influenza Bviruses that circulated during previous influenza season

Due to mutations of the influenza virus, vaccines have to be constantly updated Other strategies include wearing protective masks, avoiding crowded areas and ensuring adequate nutrition and

sleep

Control:

Implementing immunisation programs along with education programs to encourage at risk individuals to bevaccinated

Isolating infected individuals to reduce spread of influenza throughout population Following quarantine procedures to prevent spread of disease from one country to another

Gather and process information to trace the historical development of our understanding

of the cause and prevention of malaria

Malaria is a disease caused by a protozoan of the genus Plasmodium.It has a complicated life cycle requiring a mosquito

of theAnophelesgenus (female) to carry the Plasmodiumto its host.

Malaria is one of the most prevalent infectious diseases, with more than 300 million cases reported and 1.53 million

deaths, mostly of African children under 5 years old each year.

Causes:

Symptoms of malaria recorded since in Ancient China Ancient Greeks noted symptoms of malaria were common in people who lived in low, moist and hot districts

near swamp

Charles Laveran in 1880 discovered pathogen that causes malaria by looking at the blood of malaria patients.Organism was classified as a protozoan and called Plasmodium

In 1897, Ronald Ross, British army doctor demonstrated that malaria was transmitted from infected patients bymosquitoes and identified anopheles mosquito was the transmitter

Prevention:

Chinese used anti fever properties of the Chinese qinghao plant Greeks and Romans built drains to remove stagnant water to reduce malarial symptoms First drug in Europe in mid 1600s was quinine Choloroquinine in late 1940s World Health Organisationintroduction of DDT 1971- active ingredient of qinghao plant, artemisisin was isolated by Chinese scientists 2000present:


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Combination of drug therapy that includes highly effective artemisinin is the only consistently successfultreatment.

Use of netting treated with long lasting insecticides Preventing being bitten by mosquitostill most effective way to prevent infection with malaria

Process information from secondary sources to discuss problems relating to antibiotic

resistance

Source of antibiotic resistance

When antibiotics are administered to treat a bacterial infection, some bacteria may possess a natural resistanceto the particular antibiotic, and so they survive and reproduce building up a population resistant to the antibiotic

It is being accelerated by:o Overuse of antibiotics for treatment of diseaseso Only taking antibiotics provided until symptoms disappearo Food producing animals are fed antibiotics to prevent infectiono Use of cleaning products that contain anti bacterial ingredients

Problems of antibiotic resistance

Micro organisms that cause diseases once easily cured, have developed resistant strains with more severeeffects and taking much longer to cure

o Second line and third line antibiotics sometimes have to be used which are more expensive and toxic Now faced with a number of infectious bacteria resistant to almost all known antibiotics

o super bugs are becoming extremely difficult to treat and eradicate Current trend indicates that in near future, some diseases will have no treatment unless a significant

breakthrough in producing more effective drugs

Strategies to slow development of antibiotic resistance

Antibiotics should only be prescribed for bacterial infections Antibiotic prescribed should target the pathogen and not be broad spectrum Taking the whole course of antibiotics Not taking antibiotics that are prescribed for someone else Not using cleaning products that contain anti microbial ingredients

Perform an investigation to model Pasteurs experiment to identify the role of microbes in

decay

1. 600ml of water was measured by a measuring cylinder and poured into a 1000ml beaker2.

Two beef stock cubes were placed into the beaker to make a clear broth. This broth was poured evenly into3 flasks (200ml each)

3. Steps 1 and 2 were repeated for 3 other flasks4. 3 flasks were fitted with S shaped stoppers while the other three were fitted with straight tubing stoppers5. These flasks were allowed to stand for 3 weeks. The appearance of each flask were observed every three

days and results recorded


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Often we recognise an infection by the symptoms it causes. The immune response is

not so obvious, until we recover.

Identify defence barriers to prevent entry of pathogens in humans:

- Skin-

Mucous membranes

- Cilia- Chemical barriers- Other body secretions

Skin:

Intact, tough outer barrier with keratin protein that covers the body and prevents penetration by microbes Fairly dry, which helps to prevent growth of pathogens Contains its own population of harmless bacteria that help to stop the invaiding microbes from multiplying Oil and sweat glands in skin produce antibacterial and antifungal substances that further inhibit the growth of

invading pathogens

Mucous membranes:

Respiratory, digestive, reproductive and urinary tracts are covered with membranes that produce a thick layer ofmucus which traps entering pathogens until removed by cilia or processes such as coughing and sneezing

Can contain the antibody IgA which prevents attachment of viruses and bacteria to epithelial surfaces Provides moist, nutritious layer in which harmless microbes live and produce substances that inhibit growth and

entry of pathogens

Pathogens overcome this barrier as many spores are resistant to heat and chemicals such as bacterial sporesChemical barriers:

Different types of chemicals secreted in different parts of body act as a barrier to invading pathogens Stomach wall secretes gastric juices that contain hydrochloric acid and protein digesting enzymes which

destroy pathogens in stomach

Alkaline conditions of intestines destroy pathogens Urinary and vaginal openings and surface of skin are also acidic which inhibits growth of bacteria

Other body secretions:

Urine is sterile and slightly acidic and flushes and cleans the ureters, bladder and urethra and helps to preventgrowth of microorganisms

Tears contain lysozymes that destroy cell walls of some bacteriasurface of the eye is cleaned and pathogensare washed away

Saliva contain lysozymes and washes microorganisms from teeth and lining of the mouth


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Identify antigens as molecules that trigger the immune response

An antigen is any molecule the body recognises as foreign and that triggers the immune response. E.g. virus, bacteria,

foreign cell, protein debris or toxin

On surface of cells in the body, there are marker molecules that identify the cell as belonging to the body. When

pathogens enter, they have chemical markers called antigens on their surface and the immune system recognises these

as not belonging to the body and is activated to destroy the foreign substance

Explain why organ transplants should trigger an immune response

When a person has an organ transplant, the new organ has different marker molecules (antigens) than that of their

own cells which activates the immune response to reject the organ in order to defend its body. To prevent this:

Tissue type of donor is matched to recipient as closely as possible so there is a high number of matchingmarker molecules les violent immune response

Treated with immunosuppressant drugs to lesson immune response so that transplanted organ is not attacked vulnerability to other pathogens is increased

o hence recipient is isolatedIdentify defence adaptations, including:

- Inflammation response- Phagocytosis- Lymph system- Cell death to seal off pathogen

Inflammation response:

Non specific defence mechanism that occurs at site of infection Release of chemicals such as histamines and prostaglandins

o cause blood vessels to dilate, increasing blood flow to site of infection or injury, causing area to becomered hot and swollen

o causes increase in permeability of blood vessels; allows movement of phagocytes from blood intotissues so they can attack invading pathogens

Plasma moves into tissues, bringing more phagocytes and producing swelling in area of infection, forcing tissuefluid into lymph and taking debris and pathogens with it

Chemicals that increase temperature are releasedinhibits growth rate of pathogens, inactivates someenzymes and toxins made by pathogens and increases rate of biochemical reactions occurring in body

Phagocytosis:

Phagocytes are specialized white blood cells or leucocytes Neutrophils:

o First to be called upon and move to site of infection, inactivating pathogenso Short acting and then self destruct after a few dayso Used by body to fight acute (short, severe) infections


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Macrophages:o Long lasting phagocytes that can either stay in tissues or travel from blood vessels into infected tissueso Used by the body t o fight chronic infectionso After foreign particle is destroyed, parts of the antigen are displayed on surface of the macrophage

Phagocytosis is not always successfulo Pathogens can sometimes repel phagocyteso Pathogens may escape before being completely destroyed

Lymph system:

As blood circulates around the body, some of the plasma moves out of the capillaries into the tissues andbecomes part of the tissue fluid

o Tissue fluid then moves into a system of vessels known as the lymphatic system The lymph system returns intercellular fluid to the blood system (point near heart), filters cell debris and

produces white blood cells (lymphocytes) responsible for the immune response

o When tissue fluid get to the lymph node, waste particles are filtered off and any foreign particles aredestroyed by macrophages

Cell death to seal off pathogens:

Cells die to seal off an area of tissue that is infected and is not being successfully being defended by the body Infected cells surrounded by a wall of dead cells

o Prevents infection from spreading to other areas and infecting themo Wall of dead cells form a capsule (granuloma or cyst)cells within will die, causing destruction of

pathogens that are infecting them

o Debris inside granuloma or cyst destroyed by macrophages that had also surrounded the walled off area

Gather, process and present information from secondary sources to show how a named

disease results from an imbalance of microflora in humans

Microflora:

Variety of microbes that live mainly on skin, intestines, colon, mouth and vagina in women Body supplies microflora with nutrients they require and conditions they need to survive Presence of microflora inhibits growth and multiplication of many pathogens that come into contact with body,

thus protecting body from contracting disease

If conditions of body change and balance of microflora is upseto Growth and multiplication of harmful pathogens resulting in disease

Candidiasis (thrush) Crohns disease

Candidiasis:

Disease caused by the fungus Candida albicans. This fungus (yeast) is part of the natural microflora of the humanbodynormally present on mucous membranes of female genital tract, mouth and respiratory tract and the

alimentary canal

No. Of C.albicans is usually kept low by competition from other microorganisms present in bodys microflora andhence imbalance of microflora results in increase of C.albicans and disease candidiasis develops


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One of the ways the natural balance of microflora can be upset is by taking antibiotics to treat a bacterial infection in

addition to reducing number of pathogenic bacteria in body, it also reduces no. of bacteria in natural population of

microfloralowers competition for C.albicansmultiplies in uncontrolled waydisease candidiasis becomes

established

MacFarlane Barnets work inthe middle of the twentieth century contributed to a

better understanding of the immune response and the effectiveness of

immunisation programs

Sir MacFarlane Burnet (18991985) was an Australian scientist and is recognized as one of the founders ofimmunology

In 1946, he developed an experimental technique that enabled him to isolate and cultivate human influenzavirus in chicken eggs

o This method produced a high concentration of the virus, enabling it to be used to develop a vaccine 1960 Developed the clonal selection theoryall the B cells and T cells for all the possible antigens are already

present in very small amounts in the immune system. When antigen is present in body, B cell or T cell specific

for the antigen is activated, cloned and the antigen destroyed

o Helped gain better understanding of the immune systemo Led to establishment of more effective immunization programs

Identify the components of the immune response:

- Antibodies- T cells- B cells

Antibodies:

Proteins, called immunoglobulins which are produced in response to the presence of an antigen in the bodyo When appropriate B cells activated, they form plasma cells that produce antibiodies

Antibodies are antigen binding siteso match the shape of the antigen they are specific foro seek out the antigen and bind to a part of it, forming the antigenantibody complex, which causes the

deactivation of the antigen

Antibodies can react with the antigen in various ways:o Neutralises toxins produced by the antigeno Immobilising, blocking or neutralising the active binding site of the antigen so it has no effect on the

body

o Cause antigenantibody complex to clump together, making them easier to eliminate by phagocytosis


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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 differences in their rolesInteraction between B and T lymphocytes

When macrophage encounters foreign particle with antigen attached to its surface, it engulfs ito Antigen present on surface is also moved to surface of macrophage

Antigen is then transported to lymph nodes


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Antigenpresenting macrophage is presented to helper T cell that has T cell receptor corresponding to theantigen

o Effect of activating the helper T cell Helper T cell can also be activated by B cells

o B cell encounters antigen that corresponds to its surface antibodies, it binds antigens to the antibodiesand process antigen, attaches it to its surface molecules and presents this to the helper T cell with

matching T cell receptors

Chemical signals in the form of cytokines are secreted by the T cell to activate more of the same helper T cellsand macrophages

o Interleukin2 activates production of clones of B cells specific to that antigen and activates cytotoxic Tcells

The mechanisms that allow interaction between B and T lymphocytes

Two types of MHC molecules allow interaction between B and T cells to be successfulo MHCI molecules present on all cells that have a nucleus and are involved in recognition of antigens by T

cells

Infected cells hold antigen on its MHCI so that cytotoxic T cell can identify it and destroy ito MHCII molecules are present only on B cells and macrophages and are involved in recognition of

antigens on macrophages by helper T cells and recognition of antigens by B cells

macrophage holds antigen on its MHCII molecule on surface and is recognised by helper T cellwith same antigen receptor and activates appropriate B and T cells

o Interaction is also helped by their close proximity to each otherThe range of T lymphocyte types and the differences in their roles

Helper T cells (Th)o Each cell has a receptor protein that recognises only one type of antigen o When Th cell is activated by presence of a particular antigen, it releases a cytokine chemical (interleukin

2) that activates the cytotoxic T cells and B cells specific for the antigen. Other cytokine chemicals that

stimulate activity of macrophages are released

Cytotoxic T cells (Tc)o Cells stimulated to produce many copies (clones) of themselves when activated by Th cells or when they

detect cells with antigen that match their own surface receptor protein

o Army of identical cytotoxic T cells move to site of infection, bind with infected cells and releasechemicals that destroy the infected cell

Memory T cellso Cells are produced at the same time as the Tc cells are multiplying and remain in the body so body can

respond more quickly to future invasions by same antigen Suppressor T cells

o Responsible for stopping immune response when infection has been defeated


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Outline the way in which vaccinations

prevent infection

Active acquired immunity:

Naturally induced Primary response


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o Sufficient antibodies are made to destroy all infecting pathogens and person recovers completelyo Memory T cells and memory B cells specific to antigen are produced and remain in body

Secondary response:o Activated if same antigen were to re enter the bodyo Memory cells activate the production of the cytotoxic T cells and the B cells o More rapid and requires less antigen to initiate ito Produces a much greater quantity of antibodieso Lasts for a longer period of time

Vaccinations:

Preparations from weakened or dead infective microorganisms (vaccines) injected into body with intention ofprovoking immunity to a disease without producing the symptoms

Vaccines:

Living but attenuated (weakened) and therefore harmless (rabies and measles) Dead (typhoid, whooping cough)

Modified toxins called toxoids (tetanus, diphtheria) Contains antigens that cause body to undergo an immune response and produce memory cells for that

particular antigen

o If body exposed to that antigen again, secondary response is activated and antigen will be destroyedbefore any symptoms of disease are experienced

Active immunisation:

Process in which the body reacts to the vaccine by going through the immune response that produces memorycells for the antigen and confers immunity to the body

Passive acquired immunity:

Involves injection of antibodies that another organism has produced in response to infection by a particularantigen to prevent a disease from developing

Does not provide long term protection Carries risk of stimulating reactions against other foreign blood proteins that might be in the vaccine

Outline the reasons for the suppression of the immune response in organ transplant

patients

Patients of transplanted organs:

Donor organ, on its surface, have marker molecules that are different from the marker molecules on thecells in the recipients body

marker molecules on donor organ act as antigens that identify the organ as foreign materialo Immune response initiatedo Cytotoxic T cells are activated and move to transplanted organ to attack and destroy the cells

Causes rejection of transplanted organTo reduce severity of immune response:

Tissue of the donor and recipient are matched as closely as possible


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Drugs such as cyclosporine are given in order to suppress the immune system to lower risk of rejectiono Acts to reduce activity of T cellsprincipal cells that attack transplanted organo Advantageous as whole immune system is not suppressed and can still act to defend body against other

disease causing organisms

o Transplant recipient is still at much greater risk of suffering from many more infections as normalinteractions between B and T cells will not occur

Process, analyse and present information from secondary sources to evaluate theeffectiveness of vaccination programs in preventing the spread and occurrence of one

common disease, including small pox, diphtheria and polio

Vaccination programs:

Vaccination gives artificially acquired immunity from a diseaseo Once common diseases such as small pox, diphtheria and polio are now uncommon because of

successful vaccination programs

Mass immunisation programs not only prevent occurrence of disease in individuals, but also help to decreasethe spread of disease throughout the population

o Chance of infected individual coming into contact with unprotected person is lowered and transmissionof disease is effectively stoppedherd immunityEvaluation of effectiveness of vaccination programs in preventing spread and occurrence of:

Small pox:

Epidemiological studies involve the collection and careful statistical analysis of

large quantities of data. Such studies assist the casual identification of non infectious diseases

Identify and describe the main features of epidemiology using lung cancer as an example

Epidemiology is the study of diseases that affect many people. It describes the patterns and cause of diseases in

population

There are three major types of epidemiological studies:

Descriptive studies:

Provides information about:o Patterns of the diseaseo Frequency of the diseaseo Which section of population is affected (age, gender, occupation etc.)o Geographical locationo Particular time period in which individuals were affected

Early epidemiological studies on cause of lung cancer collected data including information about sex, age,smoking habits, diet, occupation and drinking habits of both smokers and non smokers


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Analytical studies:

More data is collected, statistically analysed to develop hypotheses as to the likely cause(s) of the diseaseo Casecontrol studies: compare people with disease (case) to people without the disease (control) and

look for differences in exposure to possible causes of the disease

Casecontrol study in London 1947 by Richard Doll compared patients with lung cancer topatients with other conditions. Results showed most individuals with lung cancer were smokers

and suggested link between smoking and lung cancer

o Cohort studies: studying two or more similar groups of people who are free of the disease while one isexposed to potential cause of disease

Cohort study was set up in England in 1951 by A.B. Hill following more than 40 000 doctors overa 10 year period

Intervention studies:

Used to test the effectiveness of a treatment (e.g. clinical trial of a new drug) or effectiveness of a public healthcampaign to change behaviour of population as a whole in order to decrease the incidence of disease

o E.g. Effectiveness of campaigns such as the Quit campaign to decrease no. of people smoking isevaluated using this study

Identify causes of non- infectious disease using an example from each of the following

categories:

- inherited diseases- nutritional deficiencies- environmental diseases

Inherited diseases:

Diseases that are genetically transmitted and are caused by errors in genetic informationo Down Syndrome caused by an extra chromosome 21o Cystic fibrosis caused by mutation to cystic fibrosis transmembrane conductance regulator (CFTR) gene

that is found on chromosome 7

Nutritional deficiencies:

Caused by diets lacking proper balance amount of nutrientso Anaemia, causing lethargy results from lack of iron or folic acido beriberi resulting in retarded growth, weakened heart muscle, digestive disorders and muscle atrophy

caused by a lack of vitamin B1

Caused by psychological conditions that lead to inappropriate dietsEnvironmental diseases:

Diseases caused due to lifestyle, physical factors of environment or exposure to chemicals in the environment Lifestyle diseases such as cardiovascular disease caused by substance abusealcoholism and smoking related

diseases


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Skin cancer caused by excessive exposure to UV in sunlight Lead poisoning caused by exposure to high levels of lead in atmosphere from pollution or lead based paints

Gather, process and analyse information to identify the cause and effect relationship of

smoking and lung cancer

Lung cancer:

Disease caused by the abnormal growth of cells in the lung Main causes are smoking tobacco or exposure to carcinogens in the environment (e.g. eating carcinogenic food)

Cause and effect relationship of smoking and lung cancer:

Collection and analysis of epidemiological data about lung cancer since 1947 has increased our knowledge aboutlung cancer

o Findings have universally demonstrated clear link between smoking and increased incidence of lungcancer and clear link between smoking and reduced life expectancy

The Australian Cancer Council and the State Cancer Councils all collect and report on incidence, mortality,prevalence and survival of lung cancer

Detailed studies have shown variations in the disease for factors such as age, sex, regional area and occupation Trends in lung cancer incidence reflect changes in smoking habits and that the incidence of lung cancer in males

has fallen in the past 10 years but risen in females

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

Scurvy:

nutritional deficiency diseaseOccurrence:

Rarely seen in developed countries except in people with poor diets or unusual food habits More commonly found in developing nations where fresh fruit and vegetables (rich sources of vitamin C) may

not be available

Occur in people of any age with risk groups being infants, elderly and alcoholicsSymptoms:

Initial symptoms:o Pain and tenderness in legso Swelling of long boneso Swollen, purplish and spongy gums

Advanced symptoms: Gangrene (degeneration of tissue) Reopening of old wounds Spontaneous haemorrhaging (pure/black spots on skin) Separation of once healed broken bones If left untreated, death will result


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Cause:

Results from a lack of adequate amounts of vitamin C in the daily dietTreatment/management

Treatment is very easy and simply involves the inclusion of adequate amounts of vitamin C in the diet More serious casessupplements of vitamin C taken daily Prevention involves including adequate amounts of vitamin C in dietcitrus fruits (oranges, lemons andlimes), blackcurrants, cranberries, cauliflower, spinach and tomatoes- foods rich in vitamin C (ascorbic

acid)


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Increased understanding has led to the development of a wide range of strategies to

prevent and control disease

Discuss the role of quarantine in preventing the spread of disease and plants and animals

into Australia or across regions of Australia

Australia is one of very few countries in the world that remains free of worlds most serious pests and diseasesdue to its geographical isolation

o Isolation decreased as international travel and trade increased Australia has very large agricultural industryexport more than $30 billion worth of food a yearhigh in

demand due to absence of diseases such as mad cow disease and footandmouth

o If pests and diseases were to gain entrycause huge financial loss to Australian agricultural industry Role of quarantineminimise risk of exotic pests and diseases entering Australia in order to protect our native

flora and fauna, agricultural industries, environment and health

AQIS (Australian Quarantine and Inspection Service) have strategies: Plant control:

o Involves examining all plants, parts of plants or plant products (fruits, seeds, cuttings, blubs and wood)many will be refused entry

o Only allowed if treated by quarantine officers to ensure any likely pests or pathogens are destroyed orkept at quarantine stations until any diseases present have had time to develop

Animal quarantine: Involves all animals coming into Australia spending time at quarantine stations to make sure they are

free of disease before release

Examined on regular basis for any signs of disease (several weeks) Human quarantine:

Captains of aircrafts and ships are required to notify AQIS if any passengers or crew are displaying anysymptoms of prohibited diseases such as rabies, yellow fever, malaria etc.

Aircraft are also sprayed with insecticide to kill any pests that have entered Australia with aircraft

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

Pesticides: chemicals that are used to kill the pests of plants and animals, pathogens and vectors

If pests and vectors are killed, then occurrence of disease will be prevented Three types:

o Insecticideskill insectso Fungicideskill fungal pathogenso Herbicideskill weeds

DDT used widely during WW1 to kill lice that transmitted pathogen which caused typhus DDT also widely used to killAnophelesmosquito which carries the plasmodium that causes disease malaria

controlled spread of malaria


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Effectiveness of DDT was reduced as mosquitoes built up resistance to it through process of natural selectionand many countries have since banned use of DDT due to its harmful effects on the environment

Other insecticide, such as pyrethrum are now also used which are less harmful to environment and moreeffective in controlling mosquito numberscontrols to some extent, the spread of malaria

Pesticides prevent the spread of many diseases but are limited in that vectors and pathogens build up aresistance to pesticide through process of natural selection and effectiveness decreases. Pesticides are also

being discouraged more and more due to their damaging effects on the environment

Perform an investigation to examine plant shoots and leaves and gather first- hand

information of evidence of pathogens and insect pests

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

Effectiveness of Australian quarantine service, AQIS is very high when considering its success in preventing thespread of plant and animal diseases in Australia

o Australia is relatively free from many diseases that are common in other countries Strict controls and regulations are in place that reduce risk of entry of plant and animal diseases into Australia to

a very low level

Preventing spread of plant and animal disease into Australia:

Australia has been free from foot and mouth disease sin 1872 In 2001, outbreak of this disease occurred in Britain

o Australia enforced all its normal quarantine regulations, but also banned import of any clovenhoofedanimals or products from infected regions

o Passengers entering Australia from infected areas were subject to thorough processing, and treatmentto ensure infected soil from shoes was not carried

o Mail from these areas were also inspectedPrevention of spread of plant and animal disease across region of Australia:

If quarantine measures fail, response strategies are implementedo Contingency plans are already in place

In 2007, equine flu penetrated quarantine barrier and spread was rapid whereby horses in NSW and QLD wasinfected

o Response put in place to control and eradicate disease Response involved

o Infected areas were quarantinedo All facilities, equipment, clothes, shoes and other item were decontaminatedo Horses were tracked and observed to determine extent of infectiono Activities involving horses were bannedo Awareness campaign put in placeo Susceptible animals were vaccinated

Measures were successful and was no infected properties in 2008


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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

As little as 150 years ago, incidence of plant and animal diseases were met with an emphasis on treatment andcontrol

o Treatment involving strategies to cure disease or relive its symptomso Control involving reducing the spread of disease through the population of organisms once it is already

present

More recently, emphasis has shifted to management or prevention of diseaseo Prevention involves use of strategies that stop the occurrence of disease in organismso Management commonly involves programs improving outcomes of chronic conditions and improving

the quality of lives of sufferers

A number of decades ago, when drugs such as penicillin were discovered, emphasis when dealing with diseasewas on their treatment and control

o Antibodies were used to cure bacterial infections A number of plant disease was also controlled by the use of pesticides However as antibiotic resistance developed and as pathogens became resistant to pesticides, stronger

antibiotics and pesticides had to be used

o Resistant pathogens and pest caused further damaging effects on the environment Emphasis of dealing with diseases are now prevention so that the use of drugs and development of resistant

strain and their effect are reduced

Another example is AIDS where treatmentinvolves different types of drugs, many of which have side effectso Problems would not exist if disease had been prevented in the first place

eddiethe search for better health.docx

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