Diseases and First Aid
ICSE Class 8 · Biology · Chapter 8
What this chapter covers
- Health, disease and how diseases spread
- Some common communicable diseases
- Vectors
- Prevention of diseases
- Immunity, vaccination and immunisation
- Harmful effects of tobacco, alcohol and drugs
- First aid and the first aid box
- First aid for burns and bleeding
- First aid for fractures and an object in the eye
- First aid for unconsciousness and poisoning
- First aid for snake bites and stings
Key points
- A communicable disease passes from an infected person to a healthy one; its causative agent is a pathogen such as a virus, bacterium or protozoan.
- Influenza and measles are caused by viruses and spread through droplets in the air; a vaccine prevents measles.
- Malaria is caused by Plasmodium and spread by the female Anopheles mosquito, which bites from dusk to dawn.
- Dengue and chikungunya are caused by viruses and spread by the day-biting female Aedes mosquito, which breeds in clean, still water.
- HIV spreads through infected blood, shared needles, from mother to baby and through unprotected sexual contact; it does not spread through everyday contact.
- A vector carries a pathogen from one person to another; mosquitoes, houseflies and rat fleas are vectors.
- Hygiene, clean food and water, clean surroundings, mosquito control, keeping the sick apart and vaccination prevent most communicable diseases.
- Vaccination is the act of giving a vaccine; immunisation is the process of becoming protected that follows it.
- Tobacco, alcohol and drugs are addictive and damage the lungs, liver, heart and brain; the best protection is never to start.
- First aid is the immediate help given before medical help arrives; every home and school needs a first aid box.
- Cool burns under running water; press on bleeding wounds; keep fractures still with a splint; never rub an eye; use the recovery position for an unconscious person; never cause vomiting after poisoning unless a doctor says so; keep a snake-bite victim still and rush them to hospital.
Questions answered
What is a communicable disease? Give two examples.
A communicable disease is a disease that can pass from an infected person to a healthy person, directly or through air, water, food, insects or objects. Influenza and measles are examples.
Name the causative agent and the vector of malaria.
The causative agent is the protozoan Plasmodium; the vector is the female Anopheles mosquito.
Name two diseases spread by the Aedes mosquito. When does this mosquito usually bite?
Dengue and chikungunya. Aedes bites mostly during the daytime.
Why are dengue cases highest during and after the monsoon?
Rainwater collects in pots, tyres, coolers and other containers. Aedes mosquitoes breed in this clean, still water, so their numbers rise sharply.
List four ways in which HIV does NOT spread.
Shaking hands, hugging, sharing food or utensils, and mosquito bites. (Also sharing a classroom or a toilet.)
Distinguish between vaccination and immunisation.
Vaccination is the act of giving a vaccine to a person. Immunisation is the process of becoming protected against a disease that follows, as the body makes antibodies.
Give two harmful effects each of tobacco and alcohol.
Tobacco causes cancer of the lungs and mouth, and raises the risk of heart disease. Alcohol slows reactions and causes road accidents, and damages the liver over time.
Why should a burn be cooled with running water and not covered with butter or toothpaste?
Cool running water draws heat out of the skin and reduces damage. Butter or toothpaste traps the heat and may cause infection.