Health and Hygiene | ICSE Class 6 Biology Notes

This note covers health and hygiene, communicable and non-communicable diseases, disease-causing organisms, transmission through air, water, food and insects, disease prevention, balanced diets, personal cleanliness, public sanitation and safe garbage disposal.

What do health, hygiene and disease mean?

Definition: Health is a state of complete physical, mental and social well-being. It includes more than the absence of disease.

Physical well-being concerns the body and its functioning. Mental well-being concerns the mind and feelings. Social well-being concerns relationships with other people. These aspects belong together: eating well and keeping clean do not remove the importance of supportive relationships.

A healthy person can generally perform tasks more efficiently and cope well with difficult situations. Getting enough sleep, exercising regularly and spending time with family and friends support health. Health therefore involves both personal habits and the conditions in which people live.

How is hygiene connected with health?

Hygiene includes the factors and practices that contribute to healthy living. Personal hygiene means keeping oneself clean. Public sanitation means maintaining clean shared surroundings through measures such as safe disposal of waste and human excreta, meaning waste passed from the body.

A balanced diet supplies all essential nutrients, roughage and water in the right amounts for growth and development. Nutrients are food components needed by the body. Vitamins and minerals are groups of nutrients needed for normal health. Roughage is dietary fibre, the plant-food material that helps the body remove undigested waste.

Balanced food, personal cleanliness and public sanitation work together. Clean food and water help protect against infection, while a suitable diet supplies the body's needs. A clean body alone cannot make contaminated drinking water safe.

What changes when someone has a disease?

A disease is a condition that affects normal functioning of the body or mind. A symptom is something a person feels, such as pain or tiredness. A sign is something that can be seen or measured, such as a rash or fever.

Signs and symptoms help doctors understand illness. They are not interchangeable with the cause of disease. Fever describes a bodily change; it does not name the organism or other condition responsible. Different diseases can produce similar signs, so a single sign does not establish the cause.

How do communicable and non-communicable diseases differ?

Diseases are broadly divided into communicable and non-communicable groups. A communicable, or infectious, disease can spread from an infected person to another person. A non-communicable, or non-infectious, disease does not spread from one person to another in this way.

Pathogens are disease-causing agents. These include certain bacteria, which are single-celled microorganisms; viruses, which multiply inside living cells; protozoa, which are single-celled organisms; and parasitic worms. A cell is the basic unit of a living organism. Microorganisms are organisms too small to see clearly with the unaided eye. Parasitic means living in or on another organism and obtaining nourishment from it. An infection occurs when such agents enter and establish themselves in the body. Communicable diseases involve pathogens; non-communicable diseases include conditions arising from nutrient shortages and other causes.

What does the comparison show?

Transmission means the passing of a pathogen from its source to another person. It can involve air, food, water or insects. A disease need not pass by touching someone to be communicable. Malaria is infectious even though an insect carries its pathogen between people.

Deficiency means a shortage. If the diet lacks an essential nutrient for a long time, a deficiency disease or disorder can develop. This is different from acquiring a pathogen through contaminated water. Sharing a room with someone who has a dietary deficiency does not transmit that deficiency.

Draw a box labelled “Diseases” branching into “Communicable” and “Non-communicable”. Under the first write “Common cold” and “Malaria”; under the second write “Scurvy” and “Diabetes”. The branches show categories, not a sequence of infection.

The classification concerns cause and transmission. It does not tell us that one group is harmless or that all diseases in a group need identical care. Understanding the cause helps explain why different preventive measures are needed.

Which kinds of pathogens cause communicable diseases?

Microorganisms are organisms too small to be seen clearly with the unaided eye. Bacteria and protozoa are groups of microorganisms. Not all microorganisms cause disease: some help break down waste. The term pathogen refers specifically to a disease-causing agent.

Bacteria are single-celled microorganisms. Viruses are tiny infectious agents that multiply inside living cells. Protozoa are single-celled organisms; some live as parasites. A parasite lives in or on another living being and obtains nourishment from it. That living being is its host.

Some disease-causing worms are animal parasites living inside the body. Ascariasis is caused by the roundworm Ascaris, which lives in the intestine, a part of the digestive system. A worm is not a bacterium or a virus.

Which examples belong to each group?

Contaminated means containing unwanted or harmful material, here pathogens or their infective stages. Faecal matter means solid waste passed from the bowel. Bowel is another name for the intestine. Such material can contaminate soil, food or water if it is not safely disposed of.

Cholera can cause diarrhoea, the passing of frequent loose stools, and dehydration, excessive loss of water from the body. Common-cold features include a blocked or runny nose, sore throat and cough. These examples connect a disease name with bodily changes without treating those changes as a diagnosis.

Note: The organism that causes a disease and the organism that carries it may be different. Malaria is caused by a protozoan called Plasmodium. The mosquito carries this parasite; it is not itself the malaria pathogen.

How can infections spread through air?

Some respiratory infections spread when an infected person coughs or sneezes. Respiratory means relating to breathing. Small droplets released into the air can contain pathogens. Another person may acquire infection by breathing in these droplets.

What happens in the common-cold transmission sequence?

1. An infected person has common-cold viruses in the nose or respiratory passage, the route through which air passes during breathing.
2. Coughing or sneezing releases droplets containing viruses into the surroundings.
3. Another person inhales infected droplets, or encounters viruses through contaminated objects.
4. The viruses can infect the person's nose and respiratory passage, leading to the common cold.

This sequence explains why infection can spread without sharing a meal. It also explains why covering a cough and keeping hands clean address different parts of transmission. Droplets can pass directly through the air, while contaminated objects provide an indirect route.

Indirect contact means contact through an object rather than directly with the infected person. Pens, books, cups and doorknobs are examples of objects through which common-cold viruses can be transmitted. Personal items such as towels and handkerchiefs should not be shared.

How can this route be interrupted?

Cover the mouth and nose while coughing or sneezing, wash hands with soap and water, and avoid close contact with an infected person's belongings. Wearing a mask in crowded places provides protection. Staying at home and resting when unwell helps recovery and minimises spreading disease to others.

Draw boxes labelled “Infected person”, “Droplets from coughing or sneezing” and “Another person inhales droplets”. Join them with arrows showing the direction of transmission. Beside the droplet stage write “Cover mouth and nose”.

The arrows show a possible route of infection, not a promise that every encounter causes illness. Only a few exposures to infectious agents result in disease because the body can defend itself against most of them. Preventive habits reduce opportunities for spread while care for an unwell person remains important.

How do contaminated food and water spread disease?

Food and drinking water can carry pathogens into the body. Cholera and typhoid are bacterial examples associated with this route. Amoebiasis is a protozoal example. Ascariasis shows that contaminated food and water can also carry the eggs of a parasitic worm.

The intestine is exposed when contaminated material is swallowed. Safe disposal of excreta, clean drinking water and hygienic food handling therefore belong together. A person can keep their body clean yet remain exposed if their drinking water contains pathogens.

How does a roundworm infection pass to another person?

1. Ascaris lives as a parasite in the intestine of an infected person.
2. Its eggs leave the body along with the person's faeces.
3. The eggs contaminate soil, water or plants when faecal material reaches them.
4. Another person acquires the infection by consuming contaminated water, vegetables or fruits.

This sequence links an individual infection with the condition of the surroundings. The eggs are the stage passed out in faeces. Describing the route simply as “worms travel through water” misses the important distinction between the intestinal worm and its eggs.

How can houseflies contaminate food?

Amoebiasis is caused by the protozoan Entamoeba histolytica. Houseflies can act as mechanical carriers, meaning that they transfer the parasite from infected faeces to food. Food and water contaminated with faecal matter are the main sources of this infection.

Keeping food clean, consuming properly cooked food and safe drinking water, maintaining personal hygiene and disposing of excreta properly help prevent food- and water-borne infections. Water-borne means carried through water. Boiled drinking water is a preventive measure for diseases such as cholera and typhoid.

Draw four linked boxes: “Infected person's intestine”, “Eggs in faeces”, “Contaminated water, vegetables or fruits” and “Another person swallows eggs”. Label the arrows “Possible transmission route”. Add “Safe excreta disposal” beside the second box.

Each measure protects a different point in the route. Clean hands concern personal behaviour; safe excreta disposal concerns sanitation; safe drinking water concerns what enters the body. A complete prevention explanation connects these measures with the route instead of simply saying “keep clean”.

How do insects transmit disease, and how can their spread be controlled?

A vector is an organism that carries a pathogen from one host or place to another. Mosquitoes and houseflies can serve as vectors. They do not all transmit pathogens in the same way: a mosquito may transmit through its bite, whereas a housefly can contaminate food.

Malaria is caused by Plasmodium, a protozoan parasite. An infected female Anopheles mosquito transmits it through a bite. Malaria can involve high fever, profuse sweating and periodic chills. “Periodic” means occurring repeatedly at intervals; it does not mean continuous shivering.

What is the simplified malaria transmission sequence?

1. A female Anopheles mosquito bites a person infected with the malaria parasite.
2. The parasites enter the mosquito and undergo further development there.
3. Infective forms of the parasite reach the mosquito's salivary glands, which produce saliva.
4. When the infected mosquito bites another person, it introduces parasites into that person's body.

This account shows why the bite of an infected mosquito matters. A mosquito bite alone does not establish that malaria has been transmitted. It also shows why controlling mosquitoes can interrupt transmission even though the mosquito and the disease-causing protozoan are different organisms.

Which measures reduce mosquito transmission?

Breeding means reproduction. Avoiding stagnant water, meaning water that remains standing, and regularly cleaning household coolers help control mosquito breeding places. These measures act on the surroundings. They complement protection against bites.

Mosquito nets, long-sleeved clothes and repellents help protect against mosquito bites. A repellent is a substance used to keep insects away. Wire mesh on doors and windows helps prevent mosquitoes from entering houses. Keeping the environment clean supports these personal measures.

Dengue is another mosquito-transmitted disease, but its pathogen is a virus rather than a protozoan. Thus “spread by mosquitoes” identifies a transmission route, not the pathogen group. Malaria and dengue share important preventive measures even though their causes differ.

Remember the distinction between cause, carrier and prevention. Plasmodium is the cause of malaria; an infected female Anopheles mosquito is the carrier; controlling breeding places and avoiding bites are preventive measures. Confusing these roles produces an incomplete explanation of disease spread.

How do balanced diets help prevent non-communicable diseases?

Non-communicable diseases include deficiency diseases, caused by a prolonged lack of particular nutrients. They also include conditions linked to lifestyle and the environment. Lifestyle means everyday patterns of living, including food choices, physical activity, rest and other habits.

Vitamins and minerals are groups of food components needed for normal health. A shortage of a particular vitamin or mineral can have a recognisable effect. Eating enough food by quantity does not necessarily supply every nutrient the body needs.

Which shortages produce which deficiency conditions?

Iodised salt is common salt mixed with the required quantities of iodine salts. The anaemia example here concerns iron deficiency. Anaemia is a condition in which the blood has insufficient healthy red blood cells or haemoglobin, the oxygen-carrying substance in those cells.

The word “some” in the sources column matters: the listed foods are examples, not complete lists. Sunlight exposure is included as a source associated with vitamin D; it is not a food. The table connects shortages with conditions without suggesting that a symptom alone proves a deficiency.

Does everyone need an identical diet?

Nutritional requirements may vary with age, physical activity, health status and other factors. A balanced diet therefore concerns suitable amounts, not an identical plate for every person. It includes essential nutrients, water and roughage, rather than one supposedly protective food.

Healthy eating and regular exercise also support prevention of lifestyle-associated problems. Such diseases are usually linked to lifestyle, diet and/or environment. Diabetes often develops through a combination of factors; it should not be explained as having one simple cause.

Healthy habits can often prevent non-communicable diseases, but this does not mean every such disease is preventable through diet alone. Some conditions need ongoing medical care. Prevention and treatment are different: reducing the chance of disease does not replace care after illness develops.

Which personal hygiene habits help protect health?

Personal hygiene involves keeping the body clean and using clean food and water. It contributes to preventing many infectious diseases. Hygiene is most useful when linked to a route of spread: washing hands addresses contamination, while covering a cough addresses droplets entering the surroundings.

Why is handwashing important?

Washing hands with soap and water removes pathogens. Frequent handwashing is a preventive measure for infections such as the common cold. This does not make soap a cure for an infection already established inside the body; it helps reduce opportunities for transmission.

Cleanliness also includes care with personal belongings. Avoid sharing towels and handkerchiefs, and keep food and drinking water clean. These actions address ways in which infectious material can move between people or enter the body.

How do daily habits fit together?

• Body cleanliness: keep the body clean as part of everyday personal hygiene.
• Hand cleanliness: wash hands with soap and water to remove pathogens.
• Respiratory hygiene: cover the mouth and nose while coughing or sneezing.
• Food and water hygiene: consume clean food and safe drinking water.
• Care during illness: stay at home and rest when unwell to support recovery and minimise spread.

Health also needs nutritious food, physical activity and proper sleep. These are healthy-living practices, even though they do not all remove dirt or interrupt the same transmission route. A useful routine includes care for both the body and mind.

Rest gives the body and mind time to recover. Spending time with friends and family supports mental and social well-being. A hygiene lesson should therefore connect cleanliness with broader health rather than treating a visibly clean appearance as the complete meaning of health.

Note: Preventing spread does not require blaming the person who is ill. Support recovery, follow sensible precautions and seek appropriate care. An infection is a biological event, not evidence that someone deserves exclusion or unkind treatment.

These habits work alongside public sanitation. A person can wash carefully, yet depend on shared arrangements for clean water and safe waste disposal. Personal responsibility and community action address different parts of the same health problem.

How do clean surroundings and safe garbage disposal protect the community?

Garbage is discarded solid material from everyday activities. Segregation means separating waste into suitable groups before disposal. Keeping waste out of shared spaces and arranging safe collection are parts of public sanitation, alongside safe disposal of human excreta.

Waste left near food or water can contribute to contamination. Public hygiene includes proper waste disposal and cleaning water storage structures. Safe sanitation matters particularly for infections transmitted through food and water, including typhoid, amoebiasis and ascariasis.

How should waste be separated and handled?

Keep food and plant waste separate from materials such as plastic, metal and glass. Use suitable covered containers and hand waste over through the local collection system. Do not scatter garbage in streets, drains or water sources. These are practical ways of keeping surroundings clean.

Biodegradable waste can be broken down by living organisms such as microorganisms. Fruit and vegetable peels and fallen leaves can undergo this process. Decomposition is the breakdown of complex material into simpler substances. Some bacteria and fungi, a group including moulds and mushrooms, carry out this work.

Some fungi help decompose waste. Thus the presence of microorganisms is not automatically harmful: their effects depend on which organisms are present and what they do.

How can plant waste return nutrients to the soil?

Microorganisms act on plant waste and slowly turn it into simpler, nutrient-rich manure, material added to improve soil fertility. Fertility means the soil's ability to support plant growth. Gardeners collect dry leaves and plant waste in pits for this purpose.

Manure formation needs an appropriate moisture level and suitable temperature. The nutrients return to the soil and help plants grow. This is a useful way to understand the value of separating plant waste rather than treating every discarded material as identical.

Safe waste disposal, clean water and control of mosquito breeding places serve different purposes. Garbage collection does not by itself remove stagnant water, and mosquito nets do not make contaminated food safe. Community hygiene needs measures matched to each route of disease transmission.

Health awareness means understanding these connections and sharing accurate information with friends and family. Explain the action together with its purpose: clean water helps interrupt water-borne transmission, and avoiding standing water helps control mosquito breeding. Clear explanations make preventive habits easier to understand.

Glossary

• Health — Complete physical, mental and social well-being, extending beyond simply being free from disease.
• Hygiene — Practices and conditions that contribute to healthy living, including personal and environmental cleanliness.
• Disease — A condition that disturbs the normal functioning of the body or mind.
• Symptom — A change felt by an unwell person, such as pain, dizziness or tiredness.
• Sign — A bodily change that can be observed or measured, such as fever or rash.
• Pathogen — A disease-causing agent, such as a harmful bacterium, virus, protozoan or worm.
• Communicable disease — An infectious disease that can pass between people through a route of transmission.
• Non-communicable disease — A disease that does not pass between people as an infection does.
• Vector — An organism that carries a disease-causing agent from one host or place to another.
• Parasite — An organism living in or on another living being and obtaining nourishment from it.
• Deficiency disease — A disease caused by a prolonged shortage of a particular essential nutrient.
• Balanced diet — A diet providing essential nutrients, roughage and water in suitable amounts for growth and development.
• Sanitation — Measures that maintain clean surroundings, including safe disposal of waste and human excreta.
• Segregation — Separation of discarded materials into suitable groups before their collection, treatment or disposal.
• Decomposition — Breakdown of complex material into simpler substances through the action of organisms such as microorganisms.

Common errors and misconceptions

• Misconception: Health means having no fever. Correct: Health includes complete physical, mental and social well-being; the absence of one sign of illness is insufficient.
• Misconception: All microorganisms are harmful. Correct: Some cause disease, while others help decompose plant waste and return nutrients to soil.
• Misconception: A mosquito is the pathogen causing malaria. Correct: Plasmodium is the protozoan pathogen; an infected female Anopheles mosquito transmits it.
• Misconception: All communicable diseases spread by touching a person. Correct: Transmission can involve air, contaminated food or water, and insect carriers.
• Misconception: Worm infections involve swallowing adult worms. Correct: Ascariasis can be acquired by consuming water, vegetables or fruits contaminated with roundworm eggs.
• Misconception: Scurvy spreads from one person to another. Correct: Scurvy is a non-communicable deficiency disease caused by lack of vitamin C.
• Misconception: Eating a large quantity of any food guarantees a balanced diet. Correct: A balanced diet must provide all essential nutrients, roughage and water in suitable amounts.
• Misconception: Personal cleanliness makes public sanitation unnecessary. Correct: Safe shared water supplies, excreta disposal, garbage disposal and mosquito control also help protect health.

Exam-style questions with model answers

Q1. A description of health includes complete physical, mental and social well-being. Using this information, state what health includes and explain why “no disease” is an incomplete definition. [2 marks]

1. Health includes complete physical, mental and social well-being, covering the body, mind and relationships.
2. Being free from disease alone does not establish that all three aspects of well-being are present.

Q2. Cholera is caused by bacteria in contaminated food or water. Malaria is caused by a protozoan carried by an infected mosquito. Scurvy results from vitamin C deficiency and does not spread between people. Classify each disease by transmission and give its stated cause. [3 marks]

1. Cholera is communicable because contaminated food or water can transmit the disease-causing bacteria to another person. Its pathogen group is bacteria.
2. Malaria is communicable because an infected mosquito carries its pathogen to another person. Its cause is a protozoan, rather than the mosquito itself.
3. Scurvy is non-communicable because the vitamin deficiency does not pass between people. The stated cause is a shortage of vitamin C.

Q3. An infected person releases virus-containing droplets by coughing. Another person may inhale them, and contaminated personal items can also transmit infection. Covering coughs, washing hands with soap and water, avoiding shared personal items reduce spread. Resting at home when unwell supports recovery and minimises spread. Explain these four precautions. [4 marks]

1. Covering the mouth and nose while coughing addresses the release of virus-containing droplets into the surroundings, interrupting the stated airborne route.
2. Washing hands with soap and water removes pathogens from the hands and helps reduce opportunities for transmission through contamination.
3. Avoiding shared personal items limits the indirect route in which an object carries infectious material from an infected person to someone else.
4. Resting at home when unwell helps recovery and minimises opportunities to spread infection to other people through droplets or shared items.

Q4. Ascaris, a parasitic roundworm, lives in an infected person's intestine. Its eggs pass out in faeces and may contaminate water, vegetables or fruits. Another person can swallow the eggs with these materials. Describe this transmission route in four stages. [4 marks]

1. The infected person's intestine contains Ascaris, a parasitic roundworm. This person is the starting point of the transmission route described.
2. Roundworm eggs leave the infected person's body in faeces. The material passing out contains the stage that can spread the infection.
3. Faecal contamination brings eggs into water or onto vegetables and fruits. These materials can then carry eggs to another person.
4. Another person consumes contaminated water, vegetables or fruits and swallows the eggs, thereby acquiring the roundworm infection through this route.

Q5. Plasmodium, a protozoan parasite, causes malaria. A female Anopheles mosquito takes in the parasite when biting an infected person, and an infected mosquito can transmit it in a later bite. Nets reduce bites; removing stagnant water controls breeding places. Explain the pathogen, carrier, transmission link and these two preventive measures. [5 marks]

1. The pathogen is Plasmodium, the protozoan parasite that causes malaria. Naming it identifies the biological cause of the disease.
2. The carrier is an infected female Anopheles mosquito. Its role is to transmit the pathogen rather than to be the pathogen.
3. The mosquito takes in parasites from an infected person and can introduce them into another person during a later bite.
4. A mosquito net helps reduce bites, so it acts at the point where an infected mosquito could transmit the parasite.
5. Removing stagnant water controls mosquito breeding places. This addresses conditions supporting the carrier and complements personal protection provided by nets.

Q6. Use these facts: vitamin C deficiency causes scurvy; oranges supply vitamin C; iodine deficiency causes goitre; iodised salt supplies iodine; iron deficiency can cause anaemia; green leafy vegetables supply iron. Give three deficiency-and-food pairs, explaining each. [3 marks]

1. Scurvy is linked to vitamin C deficiency. Oranges provide vitamin C, so including them in a balanced diet helps address that shortage.
2. Goitre is linked here to iodine deficiency. Iodised salt provides iodine, connecting the named dietary source with the nutrient that is lacking.
3. Iron-deficiency anaemia is linked to a shortage of iron. Green leafy vegetables supply iron and therefore provide a relevant dietary source.

Q7. Safe excreta disposal protects food and water from faecal contamination. Segregation separates waste groups; microorganisms break down plant waste into nutrient-rich manure that returns nutrients to soil; covered containers hold garbage; collection removes discarded material from shared surroundings. Using these facts, explain five parts of a sanitation plan. [5 marks]

1. Arrange safe disposal of human excreta so that faecal material does not contaminate food or water used by other people.
2. Segregate discarded materials into suitable groups. This separates plant waste from other materials and prepares the groups for appropriate handling.
3. Use suitable plant waste for manure formation. Microorganisms break down this material and return its nutrients to the soil.
4. Keep garbage in suitable covered containers. This provides an organised place to hold discarded material before it is collected.
5. Arrange collection of the stored waste. Removing it from shared surroundings completes the collection part of the plan and supports environmental cleanliness.

Key takeaways

• Health includes physical, mental and social well-being; hygiene and healthy daily habits contribute to all-round health.
• Communicable diseases involve pathogens and can spread through air, contaminated food or water, or insect carriers.
• Bacteria, viruses, protozoa and parasitic worms include disease-causing agents; their examples must be classified correctly.
• Plasmodium causes malaria, while an infected female Anopheles mosquito carries the parasite between people.
• Ascariasis can spread when roundworm eggs from infected faeces contaminate water, vegetables or fruits that another person consumes.
• A balanced diet provides essential nutrients, roughage and water in suitable amounts and helps prevent dietary deficiency diseases.
• Soap-and-water handwashing, respiratory hygiene, safe food and clean drinking water help interrupt routes of infection.
• Public sanitation includes safe waste and excreta disposal, while controlling stagnant water helps reduce mosquito breeding places.

Test yourself

Which three aspects belong in the definition of health?

Health includes complete physical, mental and social well-being, rather than merely the absence of disease.

How does a symptom differ from a sign?

A symptom is felt by the person, such as pain. A sign can be observed or measured, such as fever.

What is the difference between the cause and carrier of malaria?

Plasmodium is the protozoan that causes malaria. An infected female Anopheles mosquito carries and transmits it.

Which stage of Ascaris leaves an infected person in faeces?

Roundworm eggs leave in faeces and can contaminate water, vegetables or fruits consumed by another person.

Why can a housefly be called a mechanical carrier?

It can transfer parasites from infected faeces to food, carrying contamination between places.

Why is scurvy classified as non-communicable?

It results from vitamin C deficiency and does not spread between people as an infection.

How can microorganisms help dispose of plant waste?

Some bacteria and fungi decompose plant waste into simpler material, returning nutrients to the soil.

Why are personal hygiene and public sanitation both needed?

Personal hygiene addresses individual cleanliness, while public sanitation protects shared surroundings through measures such as safe waste and excreta disposal.