Hygiene Chapter Notes | Biology Class 9 ICSE PDF Download

Simple Personal Hygiene

• Hygiene involves caring for one’s body (personal hygiene) and surroundings (social hygiene) to stay healthy.
• Main aspects of personal hygiene include cleanliness, rest and sleep, physical exercise, and healthy habits.

Cleanliness

• Regular hand washing with soap, especially after using the toilet, prevents germ spread.
• Daily bathing keeps skin clean, removes germs, eliminates body odor, and keeps sweat pores open.
• Pay special attention to cleaning and drying skin folds like arms, legs, and toes.
• Wash undergarments and handkerchiefs daily to maintain hygiene.
• Keep hair clean by washing and combing regularly to prevent parasites like head lice.
• Brush teeth twice daily (morning and night) and rinse mouth after meals to avoid caries and gum infections.
• Avoid excessive sweets and chocolates to protect teeth.
• Breathe through the nose, not the mouth, to filter air and reduce germ intake.
• Use a handkerchief when sneezing or blowing the nose to prevent spreading germs.
• Wash eyes with clean water 2-3 times daily to prevent infections like trachoma and conjunctivitis.
• Never share towels or kajal sticks to avoid eye infections.
• Clean ears with a soft, moist swab; avoid sharp objects to prevent eardrum damage.

Physical Exercise

• Regular physical exercise is essential for all ages, especially children and young people.
• Long, gentle walks are suitable for older individuals.
• Systematic exercise improves blood circulation and overall health.

Rest and Sleep

• All body organs, including the brain, need rest through sleep.
• Infants sleep most of the day; adults need 6-7 hours of uninterrupted sleep.

Healthy Habits

• Maintain regular bedtime and meal schedules for better health.
• Avoid going to bed immediately after dinner or staying up late.
• Clear bowels daily, preferably in the morning, for proper digestion.
• Avoid tobacco, as it can cause cancer and harm health.
• Avoid stimulants and sedatives, as they disrupt healthy habits.
• Refrain from alcohol, which harms the body and society.
• Ensure living rooms are well-ventilated with fresh air and sunlight to provide oxygen and kill germs.

Social Hygiene and Sanitation

• Keep public places like schools, offices, bathrooms, and cinema halls clean.
• Ensure eating places (hotels, restaurants, dhabas) are clean and free of flies.
• Cover all food items and wash utensils, cups, and spoons with soap and hot water.
• Cover public drains and garbage, and use disinfectants like bleaching powder or lime regularly.
• Municipalities must provide clean, germ-free drinking water and efficient sewage disposal.

Control of Disease-Carriers (Vectors)

• Vectors are agents (e.g., insects, animals) that carry disease-causing pathogens.
• Houseflies, mosquitoes, and cockroaches are major disease carriers and must be controlled.

Economic Importance of Housefly

Houseflies act as natural scavengers, consuming and breaking down leftover food and organic waste. However, their severe health risks far outweigh this benefit, earning them the label of Public Enemy No. 1. They are notorious for spreading diseases such as dysentery, cholera, and typhoid.

How Houseflies Spread Diseases

1. Hairy Body and Legs: The housefly’s hairy or spiny body and legs easily pick up germs from unsanitary surfaces. When they land on food, these germs are transferred, contaminating it. Houseflies frequently rub their legs together or against their bodies, dislodging filth particles onto surfaces.
2. Saliva and Regurgitation: Houseflies contaminate food by secreting saliva to moisten it or regurgitating partially digested material from unsanitary sources.
3. Excreta: While feeding, houseflies deposit their excreta on food, further spreading harmful germs.
4. Direct Transmission: Houseflies can directly transfer infections, such as trachoma, by landing on the eyes of a healthy person after contacting the infected eyes of another.

Housefly Control Methods

1. Eliminating Breeding Sites: Regularly remove household refuse, human, and animal waste to prevent fly breeding. Covering refuse with soil promotes decomposition, generating heat that kills maggots.
2. Insecticide Spraying: Use DDT or other insecticides to spray homes and potential breeding areas to reduce fly populations.
3. Preventive Measures: Protect food by keeping it covered and inaccessible to flies. Avoid letting flies land on the body, and use protective covers, like baby umbrellas, to shield sleeping infants

Mosquitoes and Diseases

• Anopheles mosquito spreads malaria (caused by Plasmodium protozoan).
• Culex mosquito spreads filariasis (caused by Wuchereria nematode).
• Aedes mosquito spreads yellow fever and dengue (caused by viruses).
• Mosquitoes transmit germs through their saliva when biting to suck blood.

Control of Mosquitoes

• Spray DDT or other insecticides in homes and on ponds to kill adult mosquitoes and larvae.
• Fill up small ponds and puddles to eliminate breeding sites.
• Pour kerosene or oil on stagnant water to form a film that suffocates larvae and pupae.
• Introduce fish like Gambusia in ponds to eat mosquito larvae.

Cockroaches

• Common household pests that breed in manholes and sewers.
• Spoil food, paper, and clothes in kitchens and cupboards.
• May carry viral diseases, possibly including a cancer-causing virus.
• Control by spraying DDT or other insecticides in breeding areas.

Rats

• Serious pests that eat grains and other foods.
• Spread diseases via rat fleas, which may carry plague germs.
• Control by trapping, disposing of rats, or using rat poisons (raticides).

Contamination of Water and Waterborne Diseases

Contamination occurs when disease germs enter drinking water or food.

Causes of water contamination:

• Improper sewage disposal leaking into subsoil.
• People defecating or urinating near water bodies.
• Animal wastes or washings from dairies and poultries draining into water.
• Industrial wastes (e.g., mercury causing nervous system issues).
• Tannery wastes containing anthrax bacilli.
• Pesticides like DDT causing hormonal imbalance and cancer.
• Fluorides in water causing tooth and bone disorders or neuromuscular issues in high amounts.

The Three Common Water Borne Diseases

Cholera

• Caused by Vibrio cholerae bacterium in the intestines.
• Symptoms include sudden sickness, severe diarrhea, vomiting, and no urination due to water loss.
• Urea buildup in blood can be fatal.
• Spread through contaminated water, dust, flies, or dirty hands of food handlers.

Dysentery

Two types: bacillary and amoebic.

Bacillary dysentery (caused by Shigella bacterium):

• Common in children, causes diarrhea, intestinal pain, and mild fever.
• Treated with antibiotics.
• Prevent by drinking boiled water and keeping food fly-free.

Amoebic dysentery (caused by Entamoeba histolytica protozoan):

• Enters through contaminated water/food, feeds on red blood cells in the intestine.
• Forms cysts that pass through feces and infect new hosts.

Hepatitis

• Hepatitis A (infectious) is waterborne, caused by a virus.
• Symptoms include body ache, yellowish eyes, deep yellow urine, and enlarged liver.
• Prevent with hepatitis vaccine, proper hygiene, and avoiding fatty foods.

Points to Remember

• Health requires a balanced diet, personal hygiene, and good sanitation.
• Personal hygiene includes cleaning hands, skin, teeth, eyes, and ears.
• Physical exercise boosts blood circulation.
• Healthy habits like regular meal and sleep schedules promote fitness.
• Keep public places clean to prevent disease spread.
• Houseflies breed in dung; their life cycle includes egg, larva, pupa, and adult.
• Houseflies spread dysentery, typhoid, and cholera germs.
• Anopheles mosquitoes spread malaria; Culex spread filariasis.
• Mosquito life cycles differ slightly in egg, larva, and adult shapes.
• Cockroaches and rats spoil food and spread diseases.
• Contaminated water causes cholera, dysentery, and hepatitis A.
• Hepatitis A inflames the liver, causing yellow eyes and urine.