Topic : Search for Better Health

Notes for Search for Better Health

Below are the syllabus dot points of Search for Better Health. Click on the dot point to expand relvant information. These notes were written by; Emalee Callaghan Click here to donate her

1.1 Discuss the difficulties of defining the terms ‘health’ and ‘disease’

  • Health is a state of complete physical, mental and social wellbeing, and not merely the absence of disease or infirmity.
  • Disease is any condition that impairs the function of any part of a living organism. This can cover a wide range of conditions, such as a scrape on the knee to a serious organ malfunction (cancer).
  • Difficulties arise in exact definitions as they depend on the organism’s normal level of functioning, and what they expect their quality of life to be.
    • g. An individual with HIV may view themselves as healthy if the symptoms of AIDS are not expressed. However, to someone else, this person may be regarded as unhealthy – hence ambiguity arises.

1.2 Outline how the function of genes, mitosis, cell differentiation and specialisation assist in the maintenance of health

Genes are units of hereditary. They control the production of proteins for specific functions (e.g. enzymes) and ensure that correct cell processes occur through maintaining metabolism, regulating the cell cycle and achieving homeostasis – allowing for growth and repair.

Mitosis is the process whereby cells divide to produce identical copies; ensuring genes are copied exactly. Mitosis is essential for growth and repair, maintaining health by forming new cells and replacing damaged cells.

Each cell will normally differentiate to become a specialized cell, with a specialized structure and function. This is needed to develop tissues and organs that comprise systems. Good health and proper functioning in an organism results from the effective operation of the body systems.

1.3 Use available evidence to analyse the links between gene expression and maintenance and repair of body tissues

Genes control protein production (e.g. enzymes) through the production of polypeptides.

  • Enzymes are responsible for the maintenance of metabolic and physiological functions, and may impair the health of an organism if dysfunctional.
  • When body tissue is damaged, the genetic code allows new tissue to form
  • Healthy cells have their cell cycle regulated by proteins, coded by genes
  • Heat shock proteins stabilize other proteins in the cell when they are exposed to very high temperature, maintaining optimal function

Many ancient societies realised the importance of cleanliness in systems; by providing sewerage, draining and clean water in urban areas to avoid disease. These practices were based on observing connections between catching diseases, and drinking contaminated water or eating spoiled food.

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

A number of ancient societies (Chinese, Indian, Egyptian, Hebrew and Incan) had sophisticated sanitation. Others (Chinese, Egyptian, Greek and Roman) had worked methods of preserving food, whilst the Hebrews had codes for slaughtering animals and rules to prevent people from eating unclean or diseased animals (e.g. they considered pigs, which commonly had tapeworms, to be ‘unclean’).

2.1 Distinguish between infectious and non-infectious disease

Infectious diseases are caused by pathogens and can be transferred from one individual to another.

  • Modes of transmission
– Direct/indirect contact

– Droplet transmission

– Vehicle transmission

– Animal vectors (e.g. mosquito)

  • Examples:
– Malaria

– Tapeworm


– Cholera

Non-infectious diseases are not caused by pathogens, and cannot be transferred.

  • Types
    • Genetic – e.g. down syndrome
    • Environmental – e.g. asthma
    • Lifestyle – e.g. diabetes

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

The maintenance of clean food, water and personal hygiene reduce the number of pathogens we are exposed to, and hence are essential for the control of infectious diseases. Most pathogens enter the body through various openings, so precautions must be taken to minimize their entry and subsequent risk of infection and disease.

Cleanliness in Food and Water

The intake of food and water allows microorganisms to enter our body, so minimizing their number reduces the risk of infection. Fortunately, most microbes only present a health risk when they multiply and reach large numbers.

  • Rotten food scraps and wastes are decomposed by microbes, which can very readily spread diseases upon entering the body.
  • In developing countries, there is a large spread of disease due to open drains, poor sanitation, limited access to clean water, and rubbish.

Precautions taken with food include:

  • Heating (cooking food to kill microbes)
  • Cooling (refrigerating food to slow the growth of microbes)
  • Dehydrating (make the food last longer)
  • Some disease causing organisms include cholera or dysentery.

Precautions taken with water include:

  • Purifying water with chlorination, boiling water or filtration (reducing the number of microbes present in the water supply)
  • Sewage systems (diverting waste products away from the water supply)
  • Some disease causing organisms include giardiasis, typhus and botulism.

Personal Hygiene

Good personal hygiene ensures that body openings are clean to reduce the number of microorganisms that might enter our body. Sanitation refers to the maintenance of conditions that promote health, such as the removal of wastes. The major cause of disease is pathogens that originate from faeces.

  • Sterilization: The complete removal of all traces of microbes. This is required in situations where pathogens are particularly dangerous, e.g. surgical rooms
  • Disinfecting: Involves reducing microbes to a safe level, such as washing clothes or dishes with disinfectant

Some precautions include:

  • Covering mouth or nose when coughing or sneezing
  • Washing hands after using the toilet
  • Cleaning wounds

By practicing cleanliness in these areas, we limit the opportunity for pathogens to be passed from one person to another and thereby limit the spread of infectious disease.

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

A pathogen is a disease-causing organism. For this to occur, it must:

  • Have enough virulence (degree of pathogenicity) and be present in sufficient numbers to cause a disease
  • Be able to enter the hosts body or survive on it, without being destroyed by the host’s immune system
  • Have some way of passing from one host to another
  • Survive transmission between hosts

Pathogens can cause disease or disease symptoms in a number of ways:

  • Being present in sufficient numbers to impair the normal functioning of the host tissue
  • Directly destroy cells or tissues
  • Produce toxins (e.g. bacteria)
  • Initiating an excessive immune response by the host, which may inflict damage

2.4 Identify data sources, plan and choose equipment or resources to perform a first-hand investigation to identify microbes in food or in water

Aim: To identify microbes in food or water


–          8x sterile agar plates

–          3x water samples (different sources)

–          Yogurt

–          Bread mould sample

–          Disposable gloves

–          Permanent marker

–          Sticky tape

–          Inoculating loop

–          Bunsen burner and heat mat


  • Seal and do not open the petri dishes again after exposure
  • Correctly autoclave exposed petri dishes prior to final disposure
  • Wash hands after experiment to avoid contamination
  • Wipe down the bench with alcohol after experiment to prevent the spread of bacteria



Microorganisms in water:

  1. Collect 4 petri dishes with agar
  2. Pipette 0.5mL of pond water into one petri dish, and gently rock it to cover the surface
  3. Repeat for fast water and stagnant water. Leave the last plate unexposed.
  4. Seal each plate with sticky tape, and label
  5. Incubate for 4 days, at 30oC
  6. After 4 days, draw observations of colony growth (size, colour and shape)

Microorganisms in food:

  1. Collect 4 petri dishes with agar (two with added powdered milk)
  2. Inoculate one agar-only dish with mouldy bread
  3. Inoculate one agar-powdered milk with yogurt
  4. Leave remaining dishes as controls
  5. Seal each plate with sticky tape, and label
  6. Incubate for 4 days, at 30oC
  7. After 4 days, draw observations of colony growth (size, colour and shape)


The fast flowing water had the least number of colonies, whilst the stagnant and pond water were relatively even. More micro-organisms are present in pond water; and stagnant water is still, allowing microbes to reproduce easier. All water sources had similar colonies with smooth white/cream coloured colonies.


  • Do not open the incubated plates after exposure, to ensure the bacterial colonies are isolated (control)
  • When agar is dissolved in water, nutrients suitable for microbes can be added to it before setting. If a microbe contacts the agar, it will grow and reproduce to form a visible colony

2.5 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

3.1 Describe the contribution of Pasteur and Koch to our understanding of infectious disease

Scientists in the mid 1800s widely believed in the Theory of Spontaneous Generation, whereby living organisms (such as maggots, mould and mice) could arise spontaneously from non-living matter, especially when decaying (e.g. grain).

Louis Pasteur

Pasteur proposed the ‘germ theory of disease’ upon discovering that microorganisms (germs), rather than spontaneous generation, cause infectious diseases.

  • Used flasks with different shaped necks filled with boiled broth, exposing them to open air
    • Straight-neck flask developed cloudy bacterial growth
    • Swan-necked flask remained clear
  • Pasteur concluded that germs in the air fell unobstructed down the straight-neck flask and contaminated the broth, but were trapped in the swan-necked flask.
    • Disproved spontaneous generation as germs did not appear in both.
    • Demonstrated that all microorganisms come from pre-existing microorganisms.
  • Developed the technique of pasteurisation by showing that heating wine to 55oC for several minutes could kill any microbes.

Robert Koch

Koch provided proof that was needed to convince people that microscopic pathogens caused disease. He worked with the disease anthrax that affected sheep. He was able to isolate the bacterium, grow it in a pure culture and demonstrate that it was capable of inducing anthrax in healthy animals. His experiment led to the development of Koch’s Postulates:

  1. Association: the suspected pathogen must be consistently associated with the diseased plant (or animal)
  2. Isolation: the pathogen must be isolated and grown in pure culture and its characteristics described
  3. Inoculation: the pathogen from pure culture is inoculated into a healthy plant of the same species or variety and it must produce the same symptoms and signs
  4. Re-isolation: the pathogen is re-isolated from the inoculated plant and its characteristics must be the same as the organism initially isolated in step 2

3.2 Distinguish between: prions, bacteria, fungi, viruses, protozoans, macro-parasites

3.3 Identify the role of antibiotics in the management of infectious disease

Antibiotics are chemical compounds that inhibit the growth and development of bacteria.

  • Can be synthetic or naturally occurring
  • Inhibit cell wall/membrane formation, g. penicillin
  • Interfere with nucleic acid metabolism
  • Disrupts cell division
  • Whilst they are important in treating bacteria-caused diseases, antibiotics have no effect on viruses. Their misuse has led to antibiotic resistance in many populations of bacteria.
  • They are not as toxic to eukaryotes due to their chemical design (prevents harm to fungi, which produce antibiotics to prevent bacteria competing with them for nutrients)
  • Antibiotics kill existing cells, and hence are not usually used to prevent infection
  • Can be disadvantageous by killing beneficial bacteria called ‘microflora’ that compete with pathogens for living space.

3.4 Perform an investigation to model Pasteur’s experiment to identify the role of microbes in decay

Aim: To perform a first-hand investigation that models Pasteur’s experiment, to demonstrate that microbes exist in air and can cause decay.


–          4x conical flasks

–          2x S-shaped stoppers

–          2x straight-necked stoppers

–          Bunsen burner & heat mat

–          Tripod & gauze

–          2x beef stock cubes


  • Wash hands after experiment to avoid contamination
  • Wipe down the bench with alcohol after experiment to prevent the spread of bacteria



  1. Prepare broth by dissolving 2 beef stock cubes in 1L of water
  2. Pour 100mL of broth into each conical flask
  3. Insert straight-necked stoppers onto two conical flasks. Repeat for S-shaped stoppers.
  4. Gently boil each flash for 15 minutes
  5. After 2 days, observe contents and record results.



Microbial growth was present in straight-necked flasks (bubbles, cloudiness, particulate matter) but not the S-shaped flasks. Therefore, microbes present in the air contaminated the straight-necked flasks but were trapped in the S-shaped neck, and could not contaminate the broth.


Broth was boiled to ensure each conical flash contained no microbes prior to experimenting (control).

3.5 Gather and process information to trace the historical development of our understanding of the cause and prevention of malaria

3.6 Identify data sources, gather process and analyse information from secondary sources to describe one named infectious disease in terms of its: cause, major symptoms, control, transmission, treatment, prevention, host response

3.7 Process information from secondary sources to discuss problems relating to antibiotic resistance

‘Superbugs’ are strains that are resistant to antibiotics due to their overuse, e.g. golden staph in hospitals. Therefore, it is important to complete a course of antibiotics to destroy all bacteria; preventing the selection of resistant strains.

When antibiotics were first introduced, they killed most pathogens that caused disease. Over time, their impact lessened as drug resistant pathogens arose through Darwin’s theory of natural selection.

  • Initial variation within the bacteria population where some are immune to the antibiotics
  • Antibiotics were introduced as a selecting agent, killing all except those which were immune
  • Those immune to the antibiotics survive
  • They reproduce and pass on the favourable characteristic of immunity to their offspring, increasing the number of bacteria immune to the antibiotic.

4.1 Identify defence barriers to prevent entry of pathogens in humans: - skin - mucous membranes - cilia - chemical barriers - other body secretions

Note: Microflora (beneficial microbes) and humans share a mutualistic, symbiotic relationship where both species benefit.

4.2 Identify antigens as molecules that trigger the immune response

  • Antigens are foreign protein molecules that trigger an immune response against it. They include parts of bacteria, viruses, and other microorganisms. Each pathogen carries its own antigen. The body recognizes antigens produces antibodies, which are proteins that bind with an antigen to destroy it.

4.3 Explain why organ transplants should trigger an immune response

An individual’s cells are recognized by their immune system as ‘self’. In a transplant operation from one person to another, the recipient’s body usually recognizes the proteins in the transplant as foreign, and mounts an immune response against it (due to T lymphocytes). Administering immunosuppressive drugs such as cyclosporine allows the transplant to be accepted easier, whilst closely matched tissue is more compatible. E.g. blood transfusions.

4.4 Identify defence adaptations, including: - Inflammation response - Phagocytosis - Lymph system - Cell death to seal off pathogen

The second line of defense is non-specific; occurring after the first is breached. Any pathogen will elicit the following chain of responses:

Inflammation response

Histamines are released, causing vasodilation of the blood vessels. Plasma then leaks into damaged tissue causing oedema (swelling). White blood cells consisting of neutrophils (short-lived) and macrophages (long-lived) enter tissue, whilst clotting factors block the spread of infection.


This process destroys dead or foreign cells by:

  • Attachment of phagocyte to particle (e.g. pathogen, a dead or damaged host cell, or tissue)
  • Ingestion of particle as it is engulfed in a phagocytic vacuole
  • Killing of ingested particle
  • Degradation of phagocytosed particle by enzymes

Lymph system

Returns intracellular fluid to the blood system and filters cell debris from phagocytosis. Lymph nodes are the storage/maturation sites for other white blood cells (B & T lymphocytes) that are used in the specific immune response that constitutes the third line of defense.

Cell death to seal off pathogen

As some pathogens can invade cells, release toxins, and cause uncontrolled cell death; the body can form a cluster of white blood cells (called a granuloma) that completely enclose a pathogen. The white blood cells die, killing the pathogen by isolation.

4.5 Gather, process and present information from secondary sources to show how a named disease results from an imbalance of microflora in humans

MacFarlane developed a theory that explains how an organism’s body is able to distinguish between its own cells and those from other organisms. He suggested that:

  • Individual lymphocytes have the genetic capacity to make antibiotics.
  • The lymphocytes have receptor molecules on their surface. Both the receptors and the antibodies they produce are specific to antigens.
  • When an antigen enters the body, lymphocytes with receptors will be stimulated, to differentiate and produce plasma cells containing antibodies that are specific to the antigen.

Identify the components of the immune response: • Antibodies • T cells • B cells

Antibodies are Y-shaped proteins that are made in response to a specific antigen (i.e. lock and key model). They are found in blood plasma and the lymph system. Antibodies bind to antigens and have several ways of inactivating them:

  • Complement fixation (proteins attach to antigen surface and cause holes to form – i.e. cause cell lysis)
  • Neutralisation (bind to specific sites, preventing them from attaching to cells)
  • Agglutination (cause them to clump together, making them targets for macrophages)
  • Precipitation (make them insoluble, causing them to precipitate out of solution)

T cells are a type of lymphocyte that is produced in the bone marrow and matures in the thymus gland. There are several different types of T cells including: cytotoxic T cells, helper T cells, suppressor T cells, and memory T cells. They control cell-mediated immunity.

B cells are a type of lymphocyte that both form and mature in the bone marrow. There two different types of B cells – plasma cells and B memory cells. They control antibody-mediated (humoral) immunity.

  • Plasma cells produce specific Y-shaped antibodies that bind with, and cripple/inactivate specific antigens.
  • B memory cells remain in the body and detect a later infection by the same antigen. The required antibody will then be produced quickly and in large amounts. This is called immunological memory.

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

Interaction between B and T Lymphocytes is needed to complete a specific immune response:

Macrophage (secretes interleukin 1) à activated helper T cells (secrete interleukin 2, attaches to B cell) à activated B cell à plasma cells that produce antibodies, or memory cells

  • When a pathogen enters a human body tissue, non-specific macrophages will engulf it and display its antigen on the surface at a major histo-compatibility (MHC) marker site as ‘self’ or ‘non-self’.
  • These macrophages move to lymph nodes and activate helper T-cells (by secreting interleukin 1)
  • Activated T-cells then release cytokines (such as interleukin 2) to stimulate the humoral (B-lymphocyte) & cell-mediated (T-lymphocyte) responses.
  • Humoral response – B-cells proliferate and differentiate to either plasma cells (which produce antibodies) or memory cells.
  • Cell-mediated response – T-cells proliferate and differentiate to either cytotoxic T-cells or memory cells.

Mechanisms that Allow Interaction

There are 2 main mechanisms that allow this interaction of lymphocytes, which lead to the stimulation of B cells:

  1. Secretion of interleukin 2 by the helper T cells
  2. Cell contact between the T and B cells

Types of T Lymphocytes

Helper T Cells initiate the differentiation of B cells and production of cytotoxic T-cells through secretion of interleukin 2.

Cytotoxic (Killer) T Cells attach to pathogens (priming) and secrete lymphotoxins such as perforin, or destroy it through lysis (disintegration of cell membrane)

Suppressor T Cells stop the production of both killer T cells and B cells once the antigens are removed (i.e. suppress the immune response after an infection is defeated).

Memory T Cells
circulate in the lymph and reactivate quickly and intensely, when infected by the same antigen at a later time.

5.3 Outline the way in which vaccinations prevent infection

A vaccine contains antigens that stimulate the production of antibodies and induce acquired immunity. The antigenic material can either be weakened, killed or inactivated forms of pathogens. These are introduced into the bloodstream, with the intention of providing immunity to the disease without giving symptoms. As a result, memory cells are manufactured and stored in the lymphatic system, to improve the effectiveness of the immune response if a later infection by the same antigen occurs.

Once immunity is developed, the individual is usually protected for life; however some vaccines such as tetanus are only effective for a limited amount of time. In such cases, booster shots are necessary to maintain protection. Also, the flu vaccine must be administered every year, due to many strains.

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

  • A transplanted organ is recognized as foreign (not-self) tissue by the immune system
  • Before operating, tissue types are closely matched to reduce chance of rejection
  • The immunosuppression drug cyclosporine is used to kill helper T cells that stimulate the production of antibodies and cytotoxic T-Cells, which attack foreign tissue.
  • Anti-rejection drug regime must be continued for life, making patients more prone to infections such as pneumonia because their immune systems are compromised

5.5 Process, analyse and present information from secondary sources to evaluate the effectiveness of vaccination programs in preventing the spread and occurrence of one common diseases, including smallpox, diphtheria and polio

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

Epidemiology is the study of factors involved in the occurrence, prevalence and spread of disease within a population. Large quantities of relevant data are needed in an epidemiological study for statistical analysis, to determine relationships. They should also suggest management plans, and monitor the effectiveness of these strategies.

Cause and effect is difficult to study. As it is difficult to determine absolutes, factors must be negated (controlled variables) to identify those that contribute to the prevalence of the disease. This includes developing a hypothesis, and undergoing a process of elimination, to narrow down many possible factors until there is an observable trend (correlation between cause and effect).

To investigate the relationship between lung cancer and smoking cigarettes, it is important to consider:

  • The total area investigated (region, state, country)
  • Period of time over which the study will be undertaken
  • Controls (e.g. comparing smokers & non-smokers) – the case subjects should only differ with respect to disease status and the exposure to the agent under investigation (smoking).
  • Other variables need to be assessed (e.g. diet, SES, environment, etc.) to ensure no other factors could be influencing the results.
  • The data collected needs to be statistically analysed, to examine whether there is any relationship between smoking and lung cancer.
  • If there is a definite relationship between cause (smoking) and effect (lung cancer) then the attributable risk % can be calculated and a conclusion drawn.

6.2 Identify causes of non-infectious disease using an example from each of the following categories: - Inherited diseases - Nutritional deficiencies - Environmental diseases

6.3 Gather, process and analyse information to identify the cause and effect relationship of smoking and lung cancer.

Establishing cause and effect relationships for possible carcinogens has been particularly difficult for lung cancer, as the period between exposure and illness is often many years. Therefore, it has been difficult to conclusively justify their carcinogenic nature, as many other variables during this period may have been responsible. Throughout the 1970-80s, epidemiology studies continued to collect data and compile evidence, strengthening the correlation between smoking and lung cancer. For example:

  • It is estimated that 88% of lung cancer deaths in men, and 75% in women are caused by smoking
  • Since the banning of tobacco advertising and public health programs, the % of smokers in the population has declined, paralleling the decrease in lung cancer prevalence

6.4 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.

7.1 Discuss the role of quarantine in preventing the spread of disease and plants and animals into Australia or across regions of Australia

Quarantine is the controlling of the import or export of animals, plants, and other products for the purpose of controlling both the entry and spread of disease.

Whilst Australia’s geographical isolation has played a key role in maintaining a status as a country free from the world’s most severe diseases, as international trade and travel increase, this status is at risk. The Australian Quarantine and Inspection Service (AQIS) screens, inspects and clears all packages, people and other items that enter our shores. This is done to:

  • Protect the health of the human, animal and plant populations/ecosystems of Australia
  • Prevent damage to our agricultural industry
  • Protect farmers and their livelihood
    • Prevent the entry of foreign pests and contagious diseases into Australia
  • Increase our marketability for exports due to the absence of disease (e.g. Australia has declared fruit-fly free areas where some produce is grown)

7.2 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 are used to kill animal vectors that carry disease, to prevent its spread and transmission. An example is the use of DDT, which kills mosquitoes, to control and prevent the spread of malaria. In some areas, bed nets have been sprayed with pesticides such as pyrethrums, which has been effective in controlling mosquitoes.

7.3 Perform an investigation to examine plant shoots and leaves and gather first-hand information of evidence of pathogens and insect pests

Aim: To gather evidence of pathogens and insect pests on plant shoots and leaves


  1. Search surrounding trees and plants for signs of pests and pathogens
  2. Gather leaves or shoots with those pathogens present and obversve them under a light microscope
  3. Draw a scaled microscopic drawing


7.4 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

The AQIS uses a multitude of technologies such as x-rays and sniffer-dogs, to inspect items entering our shores. This prevents the entry of goods that may carry diseases or pests at airports or seaports. Affected goods are destroyed, so that the risk of disease is eradicated. Some specific examples include:

  • The ‘hand, foot and mouth disease’ that affects sheep and cattle was effectively prevented due to banning meat products from that area, and checking passengers. This ensured no contamination was introduced into the agriculture industry.
  • From an interstate perspective, the Equine flu in 2007 affected horses in NSW & QLD. Measures were introduced to stop the spread of the flu, such as vaccines, cancelling events, quarantining affected horses, and creating awareness campaigns.

7.5 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 of prevention of disease

There has been a shift from treating the disease once it emerges (reactive) to preventing its occurrence (proactive). This is evident in agriculture, where genetically resistant crops are grown so that the plants do not have to be sprayed for diseases later in life. Animal diseases such as foot and mouth, rabies and plum pox, are managed by preventing infected organisms from entering the country. Worldwide immunisation has also eradicated diseases such as small pox. Preventative measures include:

  • Avoiding contact (physical/sexual) with infected people
  • Sterilisation of water supplies
  • Hand washing and hygiene
  • Proper food hygiene
  • Adequate sewerage