Diseases and First Aid | ICSE Class 8 Biology Notes

This note covers health and disease, communicable diseases, their causes and transmission, prevention, immunity and vaccination, harmful effects of tobacco, alcohol and drugs, and first aid for injuries and sudden illness.

What are health, disease and communicable diseases?

Health means physical, mental and social well-being. It involves more than being physically fit or having no obvious illness. A balanced diet, which supplies the nutrients the body needs, personal cleanliness and regular exercise help maintain health.

A disease is a condition in which the normal functioning of an organ or body system is adversely affected. A symptom is a change experienced by an ill person, such as pain. A sign is an observable indication of illness.

How are infectious and non-infectious diseases different?

Communicable diseases, also called infectious diseases, can spread from an infected person to another person through particular routes. These routes include air, contaminated food or water, certain body fluids and transmitting animals. The route depends on the disease.

Non-communicable diseases do not spread between people through infection. Deficiency diseases, inherited (genetic) disorders and lifestyle-related problems are examples of non-communicable conditions. A disease is not necessarily communicable simply because it is serious.

Definition: A pathogen is a disease-causing biological agent. Bacteria, viruses, fungi, protozoans and parasitic worms include agents that can cause disease in humans. Bacteria are single-celled organisms; viruses reproduce inside living cells; fungi are organisms such as moulds and yeasts.

Protozoans are microscopic, single-celled organisms; some are parasites. A parasite lives in or on another organism, called its host, and obtains nourishment from it. Most parasites are pathogens because they harm their hosts.

A vector is a transmitting animal that carries a disease-causing agent between hosts. The vector and the pathogen have different roles. In malaria, the mosquito transmits the infection, while a protozoan causes the disease.

Recognising these distinctions helps connect prevention with transmission. Clean water helps prevent infections spread through contaminated water. Mosquito control helps prevent infections carried by mosquitoes. Neither measure should be treated as a universal answer for every disease.

Which communicable diseases should be compared?

The causative agent is the agent responsible for a disease. The mode of transmission is the route by which infection spreads. A useful comparison links both of these with symptoms and prevention, rather than memorising a disease name alone.

Influenza, or flu, is a viral respiratory infection, affecting the passages and organs used for breathing. Measles is another viral infection. Both can spread through the air from infected people, whereas malaria, dengue and chikungunya involve mosquito vectors.

How do their agents, symptoms and prevention differ?

Human immunodeficiency virus is abbreviated to HIV. Immunodeficiency means reduced effectiveness of the body's defence system. HIV is the name of the virus, rather than the name of a mosquito-borne disease.

Fever occurs in several illnesses in this table. It does not, by itself, identify the cause. The table compares characteristic features for learning; a person with illness needs appropriate medical assessment rather than a diagnosis made from one symptom.

Similarly, prevention must match the route. Avoiding mosquito bites addresses malaria, dengue and chikungunya. Safe blood and injection practices address particular routes of HIV transmission. Vaccination provides protection against specific infections rather than against every communicable disease.

How does malaria spread between humans and mosquitoes?

Malaria is caused by the protozoan Plasmodium. An infected female Anopheles mosquito introduces the parasite while biting a human. The human and mosquito serve as hosts during different parts of the parasite's life cycle.

What happens after an infected mosquito bites?

1. An infected mosquito introduces sporozoites, the infective form of the parasite, into the human body during a bite.
2. The parasites reach the liver and multiply inside liver cells before entering the blood.
3. They attack red blood cells, the blood cells that carry oxygen. Multiplication and rupture of these cells are associated with chills and high fever.
4. When another female Anopheles mosquito feeds on an infected person, it takes up stages of the parasite with the blood.
5. The parasite develops further inside the mosquito. Infective stages reach its salivary glands and can enter another human during a later bite.

The parasite therefore needs both hosts to complete its life cycle. The mosquito is also the vector. Calling the mosquito the cause of malaria leaves out the parasite that actually develops inside the human body.

The drawing links a mosquito biting a hand with the liver, liver cells and red blood cells. Arrows continue through parasite stages taken up by a feeding mosquito, development in its gut and movement to its salivary glands. The human-host and mosquito-host parts are labelled separately.

See Fig. 7.1 in your NCERT textbook

The diagram also labels gametocytes, the sexual stages that develop in red blood cells and are taken up by the mosquito. Its arrows show the movement of the parasite between hosts, rather than a mosquito developing inside a person.

Preventing mosquito bites and reducing breeding places interrupt opportunities for transmission. These precautions complement medical care for an infected person. They do not remove a parasite that has already entered the body.

How can personal and public hygiene prevent infections?

Hygiene means practices that help maintain health and prevent disease. Personal hygiene concerns an individual's cleanliness and habits. Public hygiene concerns shared surroundings, water supplies, waste disposal and food handling.

Which measures protect food, water and shared surroundings?

Keep the body clean and use clean drinking water and food. Proper disposal of waste and excreta, the waste discharged from the body, helps prevent contamination. Water reservoirs and tanks require cleaning and disinfection, meaning treatment to destroy harmful microbes.

These measures are particularly important where infectious agents pass through food and water. Food hygiene and clean water have a different immediate purpose from mosquito nets: they address different routes by which pathogens reach people.

For infections spread through respiratory particles, reduce close exposure to infected people and follow cough and hand hygiene. A cough should be covered, and hands should be cleaned. Such precautions help limit transfer through respiratory secretions and contaminated hands.

How can mosquito transmission be reduced?

• Prevent stagnant water: avoid water collecting in and around living areas, where mosquitoes can breed.
• Clean household coolers: regular cleaning reduces opportunities for mosquito breeding.
• Use mosquito nets: these provide a physical barrier against mosquito bites.
• Screen openings: wire mesh on doors and windows helps prevent mosquitoes entering rooms.

The same general need for vector control applies to malaria and to Aedes-borne diseases such as dengue and chikungunya. Removing breeding places and preventing bites address different parts of the problem and can be used together.

Note: A pathogen, a vector and a breeding place are different things. The pathogen causes disease, the vector transmits it, and the breeding place allows the vector to reproduce.

Good health also requires balanced food, rest and regular exercise. These support the person, while specific preventive measures reduce exposure to particular infections. Prevention combines personal habits with responsibility for shared surroundings.

How do immunity, vaccination and immunisation differ?

Immunity is the body's ability to defend itself against disease-causing agents. The immune system consists of the cells, tissues and organs involved in this defence. Exposure to an infectious agent does not necessarily result in disease.

What kinds of defence does the body have?

Innate immunity is the non-specific defence present from birth. Skin forms a barrier, mucus traps entering microbes, and stomach acid and tears help prevent microbial growth. Some white blood cells, which participate in defence, engulf and destroy microbes.

Acquired immunity is specific to a pathogen and has memory. A first encounter produces a primary response of low intensity. A later encounter with the same pathogen produces a much stronger secondary response.

Antibodies are protective proteins produced by particular white blood cells in response to foreign material. An antigen is material that can trigger a specific immune response. These terms describe different participants: the antigen triggers the response, while antibodies form part of it.

What happens during vaccination?

1. A vaccine is a preparation containing weakened or inactivated pathogens, or antigenic components of a pathogen, and it is introduced into the body.
2. The immune system responds to these antigens and produces antibodies directed against them.
3. Memory cells develop, retaining the ability to recognise the same pathogen on a later encounter.
4. On subsequent exposure, recognition enables a rapid, stronger response against the invading pathogen.

Vaccination means administering a vaccine. Immunisation means the process of developing or providing protection against disease. Vaccination stimulates the body’s own protective response, producing active immunisation; the terms are related but describe an action and the protective process respectively.

In active immunity, the person's own body produces the response; this takes time. In passive immunity, ready-made antibodies are supplied. Antibodies passed from mother to infant are an example. Medical treatment with antibodies against snake venom is another.

Specificity matters: memory against one pathogen does not mean protection against every infection. Vaccination and hygiene therefore have complementary roles. The immune system prepares a response, while hygiene reduces opportunities for pathogens to enter the body.

How does HIV affect immunity, and how can transmission be prevented?

HIV attacks cells involved in immune defence. Acquired immunodeficiency syndrome, abbreviated to AIDS, describes the advanced syndrome associated with this infection. A syndrome is a group of symptoms and signs occurring together.

As immune defence becomes impaired, the person becomes vulnerable to infections that the body might otherwise overcome. Fever, diarrhoea and weight loss can occur during progression. Infection and the appearance of AIDS symptoms are separated by a time interval, rather than being simultaneous events.

Which routes transmit HIV?

• Sexual contact with an infected person can transmit the virus.
• A blood transfusion, the transfer of donated blood or blood products into a patient, can transmit infection if the blood is contaminated.
• Sharing infected needles or syringes can transfer the virus between people.
• An infected mother can transmit infection to her child, including through the placenta during pregnancy. The placenta is the organ connecting mother and developing baby for exchange of materials.

Prevention includes testing donated blood, using sterile injection equipment and avoiding shared needles. Sterile means free from living microorganisms. Safer sexual practices, including condom use, reduce sexual transmission.

Note: HIV is not spread by mere touch or ordinary physical contact. People living with HIV need care and support, and should not be isolated from family or society because of fear of casual contact.

The link between infection and immunity is central to understanding HIV. The virus weakens the very system that helps the body resist other infections. This differs from malaria, where a mosquito introduces a parasite that multiplies in liver and red blood cells.

Do not confuse the names: HIV identifies the virus, while AIDS identifies a syndrome that can result from its effects. Neither term describes a disease spread by touching a person or sharing ordinary social space.

Why are tobacco, alcohol and habit-forming drugs harmful?

Substance misuse includes using drugs for non-medical purposes or in amounts or frequencies that impair bodily or mental functions. A medicine used under medical guidance is different from the misuse of a substance for its effects.

What harm does tobacco cause?

Tobacco contains nicotine, an addictive substance, meaning it can lead to repeated use despite harm. Nicotine raises heart rate and blood pressure. Smoking is associated with increased incidence of lung and throat cancers and heart disease. Chewing tobacco is associated with increased risk of cancer of the mouth.

Tobacco smoke also increases carbon monoxide, a poisonous gas, in the blood. This reduces the oxygen carried by the blood and contributes to oxygen deficiency. The risks concern both smoking and other forms of tobacco use, not smoking alone.

How do addiction and dependence develop?

Addiction is a psychological attachment to the effects of a substance that drives repeated use despite harm. Dependence means the body develops unpleasant withdrawal symptoms when regular use is abruptly stopped. These symptoms can include anxiety, shakiness, nausea and sweating.

In some cases, withdrawal can be severe or life-threatening and needs medical supervision. Chronic use of alcohol and drugs damages the nervous system and liver. Excessive drug doses may cause coma or death; mixing drugs with alcohol increases the danger of overdose.

Coma is a state of deep unconsciousness. An overdose means taking an excessive amount of a substance. These are emergencies, not conditions to manage by experimenting with home treatments.

Curiosity, stress and peer pressure, the influence of people in one's social group, can encourage experimentation. Even using an addictive drug once can precede addiction. Avoiding pressure, discussing problems and seeking support are therefore important.

Parents, trusted friends, counsellors and medical professionals can help. Counselling supports a person in understanding and addressing difficulties. People affected by substance misuse need timely professional help rather than blame or social rejection.

What is first aid, and what should a first aider do first?

First aid is the immediate assistance given to someone who is injured or suddenly ill before professional medical care becomes available. Its purpose is to preserve life, prevent the condition worsening and promote recovery.

A first aider is a person trained to provide this initial assistance. First aid does not replace diagnosis or complete medical treatment. It helps maintain safety and stability while further help is arranged.

What is the general response to an emergency?

1. Stay calm and assess: look at what has happened and think clearly before acting.
2. Check safety: identify hazards such as traffic, fire, sharp objects or live electrical wires before approaching.
3. Call for help: summon a trained adult or medical help promptly. In India, 112 connects to emergency services.
4. Give appropriate assistance: use the first-aid skills in which you are trained, handle the person carefully and avoid rough movement.
5. Remain with the person: reassure them and observe their condition while waiting for professional help.

If a head, neck or bone injury is suspected, keep the person still and wait for trained assistance. A first aider should not create another casualty by rushing into an unsafe area. A casualty is a person injured or affected by an emergency.

What belongs in a first-aid kit?

A kit contains items such as disposable gloves, dressings, bandages, adhesive tape and scissors. A dressing covers a wound; a bandage can hold a dressing in place or support an injured part. Gauze is an open-weave material used in dressings.

The illustration shows labelled bandages, gauze roll and pads, an instant cold pack, elastic bandages, tape, a blanket, thermometer, first-aid manual, gloves, antiseptic wipes, safety pins, tweezers, scissors and emergency contact or family medical information.

See Fig. 8.1 in your NCERT textbook

Antiseptic describes a substance used to reduce microbes on living tissue. The kit must be checked regularly, used supplies replaced and expired articles discarded. Having equipment available is useful, but safe use depends on training.

How should bleeding and a nosebleed be managed?

Bleeding is the loss of blood from damaged blood vessels. A wound is an injury that damages tissue, often breaking the skin. First aid aims to limit blood loss while protecting the injured person and the helper.

What helps with an external bleeding wound?

Call for help and use gloves if available. For an external wound without an embedded object, apply firm direct pressure with a clean dressing or cloth. Keep the person still. If an object is embedded in the wound, do not pull it out or press directly on it; apply pressure around it and seek urgent medical assistance.

Bleeding that is severe or does not stop needs urgent professional care. Avoid handling blood with bare hands when protective equipment is available. Calm reassurance and careful handling remain important while help is being arranged.

What is the sequence for a nosebleed?

1. Pinch the fleshy part of the nose just below the bone with the thumb and index finger.
2. Sit down and lean slightly forwards so that blood does not flow down the throat.
3. Maintain the pressure and forward posture until the bleeding stops.
4. Afterwards, sit and rest for at least 10 minutes.

If bleeding continues after 10 to 15 minutes, or nosebleeds occur often, medical advice is needed. The forward posture is important: tipping the head backwards can direct blood towards the throat.

Four labelled steps show a person pinching the fleshy nose, sitting and leaning forwards, maintaining pressure and posture, then resting. A stopwatch beside the last instruction shows 10 minutes.

See Fig. 8.2 in your NCERT textbook

Nosebleeds usually follow damage to tiny vessels inside the nose, associated with dryness, heat, injury or pressure from blowing the nose. The external wound and nosebleed procedures have the same broad aim of controlling bleeding, but the method and body position differ.

What first aid is appropriate for burns and suspected fractures?

A burn is tissue damage caused by heat or another damaging agent. A scald is a burn caused by hot liquid or steam. A fracture is a break or crack in a bone. These injuries require different immediate responses.

How should a heat burn be managed?

First ensure that the person is away from the source of heat without putting the helper at risk. Cool the affected area with cool running water for at least 10 minutes. Do not apply ice, butter, oil or toothpaste to the burn.

Do not burst blisters, which are raised pockets of fluid in the skin, or pull away clothing stuck to the burn. Cover the area loosely with a clean, non-fluffy covering and arrange medical assessment. Extensive or deep burns require urgent medical care.

What should be done for a suspected fracture?

Keep the injured part still and obtain medical help. Do not ask the person to test the limb by walking or forcefully moving it. A painful, swollen or deformed limb after injury should be handled carefully as a possible fracture.

Do not attempt to straighten a deformed limb or push an exposed bone back into place. Immobilisation means preventing movement of the injured part. A trained first aider may use a splint, a rigid support, to help achieve this.

If a head, neck or spinal injury is suspected, avoid moving the casualty unless there is immediate danger. The spine is the column of bones along the back. Trained help is needed to decide how to support and transfer such a casualty.

The key distinction is practical: a heat burn needs cooling, whereas a suspected fracture needs protection from movement. Both need calm assistance and appropriate medical care. Neither should be treated by forceful manipulation or an improvised remedy.

What should be done for an object in the eye or unconsciousness?

A foreign body is an object that has entered a part of the body where it does not belong. Dust or another small particle in the eye can cause pain, watering and irritation. The eye is delicate and must be handled carefully.

How should an eye injury be approached?

Do not rub the eye. A loose surface particle may be rinsed away with clean water. Do not probe the eye with fingers, tweezers or another object. A particle that is embedded, or an injury with persistent pain or altered vision, needs urgent medical help.

Different injuries cannot be treated as if they were ordinary dust. An object that has penetrated the eye should be left for medical professionals to manage. The immediate aim is to prevent further injury and obtain help.

How should an unresponsive person be assessed?

Unconsciousness means loss of awareness and responsiveness. First check for danger and attempt to obtain a response, then call for emergency help. A trained first aider should open the airway before checking breathing, following emergency-operator instructions if a neck or spinal injury is suspected. Check for normal breathing promptly, for no more than 10 seconds.

If the person is unresponsive but breathing normally, a trained first aider can use the recovery position, a supported position on the side that helps keep the airway open, and monitor breathing. Suspected spinal injury requires particular care with movement.

The airway is the passage through which air reaches the lungs. If the person is not breathing normally, emergency help and immediate resuscitation are needed. Follow the emergency operator's directions and use trained assistance.

Cardiopulmonary resuscitation, abbreviated to CPR, uses chest compressions, with rescue breaths where appropriate, to support circulation and breathing. It is a practical skill to learn using a training mannequin, rather than practising on a healthy person.

Do not give an unconscious person food, drink or medicine by mouth. Remain with the casualty and keep observing breathing until professional care takes over. A change in breathing changes the emergency response needed.

How should poisoning, snakebite and stings be handled?

A poison is a substance that can harm the body when swallowed, inhaled or absorbed. Venom is a harmful substance injected by an animal through a bite or sting. These situations require prompt help rather than delay for home remedies.

What should happen after swallowing poison?

Call emergency medical services immediately and follow their directions. Do not induce vomiting or give salt water, food, drink or a supposed antidote unless a medical professional specifically directs this. Keep the container or label available to identify the substance safely.

An antidote counteracts a particular poison. There is no single household treatment suitable for every poison. Keep cleaning fluids and pesticides in their original containers and securely stored to prevent accidental swallowing.

How should bites and stings be approached?

After a snakebite, call for emergency assistance, reassure the person, minimise movement and obtain urgent hospital care. Keep the bitten part still. Do not cut or suck the bite, apply ice or tie a tight tourniquet, a band intended to restrict blood flow.

Antivenom contains antibodies against snake venom and is a medical treatment. First aid supports the casualty while this assessment and treatment are arranged. Trying to catch or kill the snake may expose another person to a bite.

For an insect sting, move away from the insects, gently remove a visible stinger without digging into the skin, wash the area and use a cold pack wrapped in cloth. Difficulty breathing, collapse or swelling of the mouth or throat requires emergency help.

How do the immediate priorities compare?

Glossary

• Health — A state of physical, mental and social well-being, beyond the absence of obvious disease.
• Pathogen — A biological agent that causes disease by interfering with the normal functioning of its host.
• Communicable disease — An infectious disease that can pass between people through a particular route of transmission.
• Vector — An animal that transmits a disease-causing agent from one host to another.
• Immunity — The body's ability to defend itself against disease-causing agents through its protective systems.
• Antigen — Material recognised by the immune system that can trigger a specific immune response.
• Antibody — A protective protein produced by particular white blood cells in response to an antigen.
• Vaccination — Administration of a vaccine to stimulate an immune response against a particular infection.
• Immunisation — The process of developing or providing protection against disease, including through vaccination.
• Addiction — Psychological attachment to a substance's effects that drives repeated use despite resulting harm.
• First aid — Immediate assistance for injury or sudden illness before professional medical care becomes available.
• Fracture — A break or crack in a bone requiring careful support and medical assessment.
• Immobilisation — Preventing movement of an injured body part to protect it from further harm.
• Venom — A harmful substance injected into the body through an animal's bite or sting.
• Antivenom — A medical preparation containing antibodies against venom, used in treating certain venomous bites.

Common errors and misconceptions

• Misconception: Every illness spreads between people. Correct: Diseases include both communicable and non-communicable conditions; their causes and routes differ.
• Misconception: The malaria parasite and its vector are the same organism. Correct: Plasmodium causes malaria; an infected female Anopheles mosquito transmits it.
• Misconception: Every fever in a mosquito-exposed person proves malaria. Correct: Several illnesses cause fever; medical assessment is needed to determine its cause.
• Misconception: Vaccination protects against every disease. Correct: The immune response and memory are directed against particular pathogens or antigens.
• Misconception: HIV spreads by touching an infected person. Correct: Mere touch and ordinary physical contact do not transmit HIV.
• Misconception: A person with a nosebleed should tilt the head backwards. Correct: Lean slightly forwards while applying pressure to the fleshy part of the nose.
• Misconception: Every swallowed poison should be vomited out. Correct: Do not induce vomiting; obtain urgent professional instructions.
• Misconception: Snake venom should be sucked out or trapped with a tight band. Correct: Avoid suction and tight tourniquets; minimise movement and seek urgent medical care.

Exam-style questions with model answers

Q1. An infected female Anopheles mosquito introduces Plasmodium into a person. Identify the pathogen and the vector, explaining their different roles. [2 marks]

1. Plasmodium is the pathogen: it is the protozoan parasite that causes malaria in the person.
2. The infected female Anopheles mosquito is the vector: it transmits the parasite through its bite.

Q2. A health chart states that malaria is transmitted by infected female Anopheles mosquitoes, whereas dengue and chikungunya are transmitted by infected Aedes mosquitoes. Water is collecting near homes, coolers are uncleaned and windows are unscreened. Suggest three preventive actions linked to these conditions. [3 marks]

1. Remove the collected water around homes to reduce mosquito breeding places. This addresses the environmental condition that allows the vectors to multiply near people.
2. Clean household coolers regularly so that they do not continue providing breeding opportunities. This is another action directed at the mosquito population.
3. Fit wire mesh to windows to reduce mosquito entry. Unlike removal of breeding sites, this provides a barrier between mosquitoes and people indoors.

Q3. A vaccine contains weakened or inactivated pathogens, or their antigenic components. Explain in four stages how it prepares protection against a later encounter with the same pathogen. [4 marks]

1. Administration introduces the vaccine antigens into the body, giving the immune system material from the pathogen to recognise and respond to.
2. The immune system responds by producing specific antibodies, protective proteins directed against these antigens, as part of the initial response.
3. Memory cells develop and retain recognition of the same pathogen after this first encounter with the vaccine material.
4. Later exposure to that pathogen stimulates a rapid, stronger secondary response, allowing the immune system to act against the invading agent.

Q4. A person says HIV spreads by touching and therefore an infected family member should be isolated. Correct these two claims. [2 marks]

1. HIV is not transmitted by mere touch or ordinary physical contact; transmission requires particular routes such as infected blood or sexual contact.
2. Isolation from family and society because of casual-contact fears is unjustified. The person needs care, support and appropriate medical attention.

Q5. A first-aid checklist requires calm assessment, scene safety, an early call for medical help, careful assistance within training and continued reassurance. An injured person awaits help near fire or live-wire hazards; rough movement could worsen the injury. First aid provides temporary support while the person’s condition is observed. Explain the purpose of each of these five requirements. [5 marks]

1. Calm assessment helps the first aider understand what happened and think before acting. Panic can interfere with choosing suitable assistance for the person's condition.
2. Scene safety protects both helper and casualty. Checking for hazards such as fire or live wires reduces the risk of the helper becoming another casualty.
3. An early call brings professional assistance into the response. First aid provides temporary support and must not be treated as a replacement for medical care.
4. Careful assistance within training helps preserve life and prevent worsening. Rough movement or an unsuitable procedure can add harm to the original injury.
5. Remaining with the person allows reassurance and observation while help arrives. It supports recovery and helps the first aider notice changes in the casualty's condition.

Q6. A conscious person has a nosebleed. The first-aid steps are to pinch the fleshy nose, sit leaning slightly forwards, maintain pressure and posture, and then rest for at least 10 minutes. Bleeding that continues after 10 to 15 minutes needs medical advice. State these four steps with their relevant details. [4 marks]

1. Pinch the fleshy part just below the nasal bone with the thumb and index finger, applying pressure at the appropriate part of the nose.
2. Sit down and lean slightly forwards. This position helps prevent blood flowing backwards into the throat during the nosebleed.
3. Maintain both the pressure and the forward posture until bleeding stops, rather than tilting the head backwards.
4. After bleeding stops, sit and rest for at least 10 minutes. Continued bleeding after 10 to 15 minutes requires medical advice.

Q7. An emergency card advises: swallowed poison requires professional instructions without induced vomiting; snakebite requires minimal movement and urgent hospital care without cutting or suction. Explain three safe actions using this advice. [3 marks]

1. For swallowed poison, call medical services and follow their instructions. Do not induce vomiting or substitute an improvised household treatment for professional advice.
2. For snakebite, reassure the casualty and minimise movement while arranging urgent hospital care. Keeping the person still supports safe transfer for assessment and treatment.
3. Do not cut or suck the snakebite. Cutting adds injury and the risk of infection, and sucking does not remove venom, so both waste time that should be spent reaching hospital.

Key takeaways

• Communicable diseases spread through particular routes; effective prevention connects the causative agent, transmission route and protective measure.
• Plasmodium causes malaria, while infected female Anopheles mosquitoes transmit the parasite between human hosts.
• Personal hygiene, clean food and water, waste disposal and mosquito control reduce opportunities for infection.
• Vaccination introduces antigens, while immune memory prepares a stronger response to later exposure to the same pathogen.
• HIV weakens immune defences but is not transmitted by mere touch or ordinary physical contact.
• Tobacco, alcohol and drug misuse can harm health and lead to addiction requiring counselling and medical help.
• First aid aims to preserve life, prevent worsening and promote recovery while professional medical assistance is arranged.
• Match first aid to the situation: control bleeding, cool heat burns, immobilise suspected fractures and seek urgent help for poisoning or snakebite.

Test yourself

What is the difference between a pathogen and a vector?

A pathogen causes disease; a vector transmits the disease-causing agent between hosts. Plasmodium and the female Anopheles mosquito illustrate the distinction.

Which mosquito group transmits dengue and chikungunya?

Infected Aedes mosquitoes transmit dengue and chikungunya, so preventing bites and reducing breeding places are important precautions.

What makes acquired immunity useful on later exposure?

It has memory, enabling a stronger secondary response when the body encounters the same pathogen again.

How does passive immunity differ from active immunity?

Passive immunity supplies ready-made antibodies. In active immunity, the person's own body produces the immune response, which takes time.

What are the three aims of first aid?

The aims are to preserve life, prevent the casualty's condition worsening and promote recovery before professional care is available.

Why should a suspected fracture be kept still?

Keeping the injured part still protects it from further harm while appropriate medical assistance is obtained.

Should vomiting be induced after swallowing poison?

No. Obtain emergency medical advice and follow professional instructions rather than inducing vomiting or giving an improvised remedy.

What must be monitored in an unconscious person?

Breathing must be checked and monitored while emergency help is obtained. Absent or abnormal breathing requires immediate resuscitation assistance.