ICSE Class 9 Biology Chapter 15 Hygiene A Key to Healthy Life

Unit 6: Health and Hygiene

Hygiene - A Key to Healthy Life

Syllabus: A brief introduction to maintaining good health.

General idea of personal hygiene, public hygiene and sanitation.

Modes of transmission: air borne, water borne, vectors (housefly, mosquito, cockroach).

15.1 Simple Personal Hygiene

Hygiene is defined as the science and practice of maintaining good health. It requires caring of one's own body (personal hygiene) and taking proper care of surroundings (social hygiene). The major aspects of personal hygiene are as follows:

1. Cleanliness

2. Physical exercise

3. Rest and sleep

4. Healthy habits

1. Cleanliness

Personal cleanliness is most essential.

(i) Hands and skin must be cleaned regularly. We are continually handling a variety of things - furniture, books, coins, currency notes, seats and supporting rods in buses, pets and other domestic animals, tools and machinery in workshops, and so on. All these objects may carry germs which may be picked up by our fingers and transferred over other parts of the body or into the mouth through food.

The practice of washing hands with soap after using toilets is very important.

A daily bath regularly keeps the skin clean and free of germs, the body odours given out in perspiration are removed and keeps the sweat pores open. Particular attention must be paid to the cleansing and drying of the various clefts and folds of the skin, for example, of arms, legs and toes.

Undergarments and handkerchiefs must be washed daily.

(ii) Hair should be kept clean by frequent washing and regular combing. This keeps it healthy and free of parasites (like head-lice).

(iii) Teeth should be cleaned at least twice a day - before going to bed at night and after getting up in the morning.

Mouth should be washed after every meal.

Too much eating of sweets and chocolates spoils the teeth causing caries and gum infections.

(iv) Breathe by Nose. One must always breathe by the nose and never by the mouth. One should blow the nose into a handkerchief and should hold a handkerchief in front of the mouth and nose while sneezing.

(v) Eyes must be cleaned and washed with clear water two or three times everyday. Trachoma and conjunctivitis are two common diseases of the eye caused through dust and through contamination by hands and towels. For preventing eye infections:

One must never share towels with others, even in the same family.

The Indian custom of applying "kajal" (soot) may sometimes lead to infections of the eyes through the shared applying sticks, so never share such sticks.

(vi) Ears should be kept clean.

The wax inside may be cleaned by soft moist swab.

One should never put any sharp pointed object into the ear, it may injure the eardrum.

2. Physical Exercise

Some physical exercise is necessary for all age groups, especially children, adolescents and young people. Long gentle walks are enough for the old. Physical exercise should be systematic and regular. It improves blood circulation.

3. Rest and Sleep

All organs of the body including the brain (mind) need rest. In general, the body obtains adequate rest by means of sleep. The amount of sleep required varies with age. The very young infants sleep for most of the day. For adults 6-7 hours continuous undisturbed sleep is sufficient.

4. Healthy Habits

One should develop good healthy habits such as going to bed at night at regular time, taking food at regular hours, etc.

In general, going to bed at late hours or immediately after taking dinner are not good habits.

Bowels should be cleared everyday preferably in the mornings.

Tobacco should be avoided - it is injurious to health and may even lead to cancer.

Taking stimulants and sedatives are unnecessary and spoil habits.

Drinking alcoholic beverages is definitely harmful to one's own body as well as to society.

The living rooms should be well ventilated for fresh air and sunlight. Fresh air brings oxygen and sunlight kills germs.

Teacher's Note

Maintaining personal hygiene through daily bathing, brushing teeth, and washing hands before meals are essential habits that protect us from infections and help us stay healthy in our everyday lives.

Progress Check

1. Fill in the blanks

(i) Cleanliness, rest and sleep, and physical exercise are a part of - hygiene

(ii) One must always breathe by the - and never by the

(iii) Fresh air brings - into the living rooms.

(iv) One must never put a sharp pointed object into the -, it may rupture the -

(v) For adults 6-7 hours of continuous undisturbed - is sufficient

(vi) The municipal bodies must ensure the supply of clean germ-free - and an efficient - disposal.

2. List any three advantages of a daily bath.

(i)

(ii)

(iii)

15.2 Social Hygiene and Sanitation

All public places such as schools, office buildings, bathrooms, lavatories, cinema halls, etc., should be kept clean.

The eating places such as hotels, restaurants, roadside dhabas and their surroundings must be kept clean and free of flies. All eatables must be covered. All utensils, cups, glass-tumblers and spoons, etc., must be thoroughly washed preferably with soap and hot water.

All public drains and garbage must be covered and some disinfectants such as bleaching powder, lime, etc., must be frequently sprinkled.

The civic bodies (municipalities, etc.) must ensure the supply of clean germ-free drinking water and an efficient sewage disposal.

Control of Disease-carriers (Vectors)

Vector is any agent that acts as an intermediate carrier of the pathogen. Many insects and other animals spread diseases. Steps should be taken to control or to eradicate them. Control of houseflies mosquitoes and cockroaches should be given maximum priority. These three are considered the worst public enemies.

Economic Importance of Housefly

The housefly is a kind of natural scavenger cleaning and consuming the left-overs of the food, etc. But the dangers which the housefly poses to human life are so serious, that it is often designated as Public Enemy No. 1. It spreads numerous diseases including dysentery, cholera, typhoid, etc.

The Manner in Which the Housefly Spreads Diseases

1. Hairy body and legs pick up filth: The body and specially the legs are hairy or spiny. They easily pick up filth containing germs from dirty places. Such a fly contaminates our food by sitting on it. A resting housefly always keeps on rubbing its legs against themselves and over the body, thus dropping particles of filth.

2. Pouring out saliva: Food is also contaminated with germs when the housefly moistens the foodstuffs by pouring out its saliva on it, or when it vomits (regurgitates) food which it has swallowed from dirty places.

3. Excreta: It deposits its excreta while it feeds, and thus contaminates human food.

4. Direct transmission of germs: Sometimes it directly conveys the infection. For example, germs of trachoma (a disease of the eyes) are directly transferred when a fly which once settled on the infected eyes of a patient, next time sits on the eyes of a healthy person.

Control of the Housefly

There are several methods to control houseflies.

1. Elimination of breeding places. All refuse from houses, and all animal and human excreta should be removed at regular and frequent intervals and disposed off in such a way that the flies cannot breed in it. If the refuse be covered by a layer of earth, enough heat is produced in it by decomposition, which is sufficient to kill the maggots, if any.

2. Spraying. Houses and breeding places should be sprayed with DDT and other insecticides.

3. Avoidance. Food should be kept well protected and covered. Flies should not be allowed to sit on the body. Sleeping babies should be protected by baby umbrellas.

Teacher's Note

Public hygiene practices like proper sanitation, clean drinking water systems, and regular cleaning of public spaces help prevent the spread of diseases in our communities and workplaces.

15.3 Mosquitoes and Diseases

1. Anopheles mosquito spreads malaria in man, monkeys and birds, etc. The malaria germ is a protozoan Plasmodium.

2. Culex mosquito spreads elephantiasis (filariasis), caused by a nematode worm Wuchereria.

3. A third mosquito, Aedes spreads yellow fever and dengue, both caused by their respective viruses.

The germs of these diseases are spread when the mosquitoes bite to suck blood. With this blood, the mosquitoes receive germs of the particular disease, which grow and multiply within their body. When such infected mosquitoes bite a healthy person, these germs are introduced into his body through the saliva. Before sucking blood the mosquito first injects its saliva into the skin, which contains a substance that prevents clotting of blood to facilitate suction.

Control of Mosquitoes

Several steps are recommended to destroy mosquitoes in different stages:

1. Spraying. Adult mosquitoes should be destroyed by spraying DDT and other insecticides in dwelling places. Spraying on ponds and marshy places kills the life-history stages.

2. Elimination of breeding places. Breeding places should be destroyed. Small ponds and puddles should be filled up.

3. Spraying on stagnant water. Kerosene or some other greasy oil should be poured over the water to make a thin film on the surface. The oil kills the larvae and pupae when they come to breathe on the surface.

4. Biological control. Certain fishes such as Gambusia should be introduced in the ponds. They selectively devour mosquito larvae.

Teacher's Note

Understanding how mosquitoes transmit diseases like malaria and dengue helps us take personal precautions such as using mosquito nets and repellents, and supporting community efforts to eliminate breeding grounds.

Progress Check

Tick-mark the correctly matched pairs of certain animals and the related diseases/habits.

(i) Culex - yellow fever

(ii) Aedes - filaria

(iii) Anopheles - malaria

(iv) Gambusia - eat up mosquito larvae

(v) Rat flea - diarrhoea

(vi) Cockroaches - Breed in man-holes

15.4 Cockroaches

These are very common household insects breeding mostly in the connecting manholes and sewers. They extend their activities to kitchens, cupboards and wardrobes. They eat and spoil food, paper and clothes. They are also suspected to be carriers of certain viral diseases, including possibly a cancer-causing virus. Spraying DDT and other insecticides in their breeding places is an effective method of control.

15.5 Rats

Rats are serious domestic pests. Besides eating grain and other foods they also spread germs of certain diseases. Rat-flea is a parasite which lives on rat's skin. It may carry germs of plague. Plague had spread as a serious epidemic during the earlier part of twentieth century in many parts of the world killing a number of people. Rats should be trapped and disposed off or be killed by suitable rat poisons (raticides).

Teacher's Note

Controlling household pests like cockroaches and rats through proper sanitation and food storage prevents contamination of our homes and reduces the risk of disease transmission.

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