Grade 10 HPE || Environmental Health and Diseases|| Notes

PART 1: INTRODUCTION TO DISEASES

🔵 Definition of Disease

Disease refers to a condition where the body or its parts do not function properly. It is derived from two words: "Dis" (lack of) and "Ease" (comfort), meaning lack of comfort or easiness.

Definition: Disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not due to any immediate external injury.

Webster's Dictionary: "Disease is the distinctive process in a particular organ or organism. It is the bad condition of the body."

PART 2: TYPES OF DISEASES

🟢 Classification of Diseases

Diseases are classified into two main categories based on their ability to spread:

1. Communicable Diseases (Infectious Diseases)

• Diseases that can spread from one person to another
• Caused by pathogens (bacteria, viruses, fungi, parasites)
• Transmitted through various modes

Examples: Cholera, Typhoid, Common Cold, Tuberculosis, COVID-19

2. Non-communicable Diseases (Non-infectious Diseases)

• Diseases that cannot spread from one person to another
• Caused by genetic factors, lifestyle, environment
• Develop over time

Examples: Cancer, Asthma, Heart Disease, Diabetes, High Blood Pressure

📊 Comparison Table: Communicable vs Non-communicable Diseases

PART 3: CYCLE OF COMMUNICABLE DISEASE

🔵 Disease Transmission Cycle

Explanation:

• Source/Reservoir: Infected person or carrier
• Pathogens: Disease-causing microorganisms
• Mode of Transmission: How the disease spreads
• Susceptible Host: Healthy person who can get infected
• New Infection: Disease develops in new host

PART 4: MODES OF DISEASE TRANSMISSION

📋 Table: Disease Transmission Modes

PART 5: FOOD AND WATERBORNE DISEASES

1. Roundworm (Ascariasis)

Cause: Intestinal worm Ascaris lumbricoides

Characteristics:

• Length: 20-30 cm
• Life cycle: About 2 months
• One female produces 200,000+ eggs daily

Symptoms:

• Abdominal pain, stomach ache
• Loss of appetite
• Nausea and vomiting
• Diarrhea
• Worms visible in stool
• Malnutrition in children

Transmission: Through contaminated food, water, or soil containing worm eggs

2. Diarrhea

Definition: Passing loose, watery stools three or more times a day

Cause: Bacterial, viral, or parasitic infections

Symptoms:

• Frequent loose, watery stools
• Dehydration
• Loss of body fluids
• Undigested food in stool
• Nausea and vomiting
• Abdominal cramps
• Weakness

Severe Dehydration Symptoms:

• Sunken eyes
• Dry mouth and skin
• Decreased urination
• Weak pulse
• In infants - sunken fontanelle

3. Dysentery

Definition: Inflammation of the intestines causing diarrhea with blood and mucus

Types:

a) Amoebic Dysentery

Cause: Entamoeba histolytica (protozoa)

Symptoms:

• Abdominal pain
• Intermittent diarrhea
• Blood and mucus in stool
• Weakness
• Loss of appetite
• Dehydration symptoms

b) Bacillary Dysentery

Cause: Shigella bacteria

Symptoms:

• Acute diarrhea
• Abdominal pain
• Frequent but small amounts of stool
• Bloody diarrhea
• Fever and discomfort
• Dehydration

🟢 Causes of Food and Waterborne Diseases

• Open defecation
• Dirty surroundings and poor sanitation
• Contaminated water sources
• Poor personal hygiene
• Drinking water from any source
• Food kept uncovered
• Eating raw/improperly washed fruits/vegetables
• Not washing hands after toilet/field work
• Eating without washing hands
• Drinking unpurified water

🟢 Prevention of Food and Waterborne Diseases

• Always use clean toilets
• Proper disposal of garbage and waste
• Keep water sources clean
• Avoid open defecation
• Use clean toilets
• Maintain personal hygiene
• Drink only purified water (boiled, filtered, chlorinated)
• Keep food covered
• Wash hands thoroughly after toilet/field work
• Wash hands before eating
• Wash fruits/vegetables properly before eating
• Drink only clean/purified water

PART 6: AIRBORNE DISEASES

1. Common Cold

Cause: Various viruses, mainly Rhinovirus

Characteristics:

• Most common infectious disease
• Affects all age groups
• Seasonal occurrence

Symptoms:

• Runny/stuffy nose
• Sore throat
• Sneezing
• Cough
• Mild fever
• Watery eyes
• Fatigue
• Headache

Transmission: Through airborne droplets from coughing/sneezing

PART 7: DISEASES TRANSMITTED BY CONTAMINATED NEEDLES

1. Hepatitis B

Definition: Liver disease caused by Hepatitis B virus (HBV)

Note: Called "Silent Killer" because many people don't know they're infected until liver damage occurs. About 20 million people die annually from Hepatitis B-related causes.

Transmission Modes:

• Infected blood transfusion
• Unsterilized needles/syringes
• Unsterilized surgical/dental equipment
• Shared razors, toothbrushes
• Sexual contact with infected person
• Mosquito bites (from infected person)
• Infected pregnant mother to child
• Tattooing with unsterilized equipment

Symptoms:

• Fatigue
• Abdominal pain
• Dark urine
• Loss of appetite
• Yellow eyes/skin (jaundice)
• Liver damage
• Can lead to liver cancer/cirrhosis

Prevention and Control:

• Maintain personal hygiene
• Use only sterilized needles/syringes
• Avoid drug abuse
• Use personal razors, toothbrushes only
• Dispose used needles properly
• Use sterilized equipment for piercing/tattoo
• Vaccinate infants at birth
• Vaccinate all children
• Practice safe sex

2. Hepatitis C

Definition: Liver disease caused by Hepatitis C virus (HCV)

Cause: Similar to Hepatitis B, transmitted through infected blood and contaminated needles

Symptoms: Similar to Hepatitis B

Note: Hepatitis B and C are NOT transmitted by:

• Casual contact
• Living together
• Sharing food
• Hugging/kissing
• Using common utensils

PART 8: NON-COMMUNICABLE DISEASES

🔵 Definition

Non-communicable diseases are diseases that cannot be transmitted from one person to another. They develop due to genetic factors, lifestyle choices, and environmental conditions.

Definition: Non-communicable diseases (NCDs) are medical conditions or diseases that are not infectious and cannot be passed from person to person.

🟢 Causes of Non-communicable Diseases

📊 Comparison: Communicable vs Non-communicable

PART 9: MAJOR NON-COMMUNICABLE DISEASES

1. Cancer

Definition: Abnormal and uncontrolled growth of cells in any part of the body

Note: Over 100 types of cancer identified. 20% of cancer deaths are due to tobacco use. 80% of cancer deaths occur in developing countries. Currently about 56 lakh people die annually from cancer worldwide. Expected to reach 1 crore 14 lakh by 2030.

Causes of Cancer:

Physical factors: UV radiation, radiation exposure

Chemical factors: Tobacco, alcohol, pollution

Biological factors: Viruses, infections

Hepatitis B - liver cancer

Helicobacter Pylori - stomach cancer

Common Cancers:

• Lung cancer (tobacco-related)
• Breast cancer (women)
• Cervical cancer (women)
• Prostate cancer (men)
• Skin cancer
• Oral cancer

Symptoms of Cancer:

• Non-healing sores/ulcers
• Unusual bleeding/discharge
• Lump/thickening in breast/body
• Changes in mole/wart
• Changes in bladder/bowel habits
• Persistent cough/hoarseness
• Difficulty swallowing
• Unexplained weight loss

Prevention and Control:

• Healthy, balanced diet
• Avoid tobacco, alcohol, smoking
• Treat any sore/ulcer immediately
• Seek prompt medical treatment
• Maintain environmental hygiene
• Healthy lifestyle habits
• Cancer awareness programs
• Control infections like Hepatitis B

2. Heart and Blood Vessel Diseases

Definition: Diseases affecting the heart and blood vessels

Note: Leading cause of death globally. About 1 crore 75 lakh people die annually from heart diseases. Expected to reach 2 crore 50 lakh by 2020.

Types:

Heart Attack - blockage in blood vessels supplying heart

Brain Stroke - blockage in blood vessels supplying brain

Peripheral Arterial Disease - blockage in limbs/extremities

Rheumatic Heart Disease - damage from rheumatic fever

a) Heart Attack and Brain Stroke

Causes:

• Blockage in arteries supplying heart
• Blockage in arteries supplying brain
• Rupture of blood vessels in brain

Heart Attack Symptoms:

• Sudden, severe chest pain
• Pain radiating to left arm/shoulder
• Sweating, nausea
• Shortness of breath
• Weakness, dizziness

Brain Stroke Symptoms:

• Paralysis on one side
• Weakness/numbness in limbs
• Slurred speech
• Vision problems
• Dizziness, headache

Prevention:

• No tobacco/alcohol/drugs
• Regular exercise and healthy diet
• Avoid fatty, spicy, junk food
• Control obesity
• Avoid stress
• Include fruits/vegetables in diet
• Regular blood pressure checkup

b) Rheumatic Fever and Rheumatic Heart Disease

Cause: Group A beta-hemolytic streptococcal infection

Age group: 5-15 years children

Process:

• Starts with strep throat
• Followed by fever within 1-4 weeks
• Affects heart valves
• 50% of rheumatic fever patients develop heart disease

Rheumatic Fever: Fever with joint inflammation
Rheumatic Heart Disease: Permanent damage to heart valves

Prevention: Treat strep throat immediately with antibiotics

3. Diabetes

Definition: Disorder where body cannot properly use glucose due to insulin problems

Note: Called "Silent Disease". WHO estimates 18 crore people worldwide have diabetes. Expected to double by 2030.

Types:

Type 1: Body doesn't produce insulin (genetic)

Type 2: Body doesn't use insulin properly (lifestyle)

Symptoms:

• Excessive thirst
• Frequent urination
• High sugar in urine/blood
• Weight loss, fatigue
• Slow healing of wounds
• Affects eyes, heart, kidneys
• Delayed recovery from infections

Prevention and Control:

• Healthy, balanced diet
• Regular exercise
• Control weight
• Avoid tobacco/alcohol
• Limit sugary foods
• Regular blood sugar monitoring
• Protect from injuries
• Take medication/insulin as prescribed

4. Asthma (COPD)

Definition: Chronic lung disease with breathing difficulty

Note: WHO estimates 8 crore people worldwide have asthma

Causes:

• Tobacco smoke
• Smoke (cooking smoke)
• Air pollution
• Dust and chemicals
• Allergens

Symptoms:

• Chest tightness
• Difficulty breathing
• Wheezing
• Coughing
• Shortness of breath during activity
• Fatigue
• In severe cases, can be fatal

Prevention and Control:

• Avoid triggers/allergens
• Live in ventilated areas
• Use mask in dusty areas
• Use clean fuel
• Keep patient comfortable
• No smoking
• Take medication as prescribed
• Immediate medical attention during attacks

PART 10: ENVIRONMENTALLY TRANSMITTED DISEASES

1. Cholera

Definition: Acute diarrheal disease caused by bacteria

Cause: Vibrio cholerae (discovered by Robert Koch in 1883)

Transmission:

• Contaminated water/food
• Through flies and dirty hands
• Contaminated utensils
• Contaminated fruits/vegetables
• Direct contact with patient

Symptoms:

• Watery diarrhea (rice-water stool)
• Vomiting
• Sunken eyes
• Muscle cramps
• Dehydration
• Weak pulse
• Severe abdominal pain
• Dry skin/mouth
• In infants - sunken fontanelle

Prevention and Control:

• Immediate reporting to health center
• Cholera vaccination
• Health education
• Isolate patient
• No open defecation
• Drink only boiled water
• Safe disposal of patient's stool/vomit
• Personal and environmental hygiene
• Avoid flies, uncovered food
• Wash hands before eating and after toilet

2. Dengue Fever

Definition: Viral disease transmitted by Aedes Aegypti mosquito

Note: About 3 crore people affected globally. In Nepal, about 300 cases annually. First Dengue Epidemic in Nepal - 2016

Breeding Sites of Dengue Mosquito:

• Clean stagnant water
• During rainy season in containers, tires, flower pots
• House drains, coolers, water tanks, coconut shells

Symptoms:

• High fever
• Fever lasting 5-6 days
• Severe headache
• Pain behind eyes
• Body rash
• Bleeding tendency
• Muscle and joint pain
• Nausea, vomiting
• Abdominal pain
• Nose/gum bleeding
• Skin spots
• Dizziness

Prevention:

• Avoid mosquito bites
• Control mosquito breeding
• Clean house surroundings
• Cover water containers
• Dispose old containers
• Use mosquito nets
• Wear full sleeves clothes
• Use mosquito repellent
• Use mesh on windows

3. Viral Influenza (Flu)

Definition: Acute respiratory infection caused by Influenza virus

Cause: Influenza A, B, C viruses (Type A most severe)

Transmission:

Droplet infection - through cough/sneeze droplets

Direct contact - living with infected person

Contaminated items - using patient's items

Patient secretions - improper disposal

Symptoms:

• Sudden fever, cough
• Headache
• Chills
• Sore throat
• Muscle pain
• Watery/red eyes
• Nasal congestion
• Body aches
• In children - abdominal pain, diarrhea

Prevention and Control:

• Immediate medical attention
• Isolate patient
• Don't share patient's items
• Safe disposal of patient's secretions
• Keep patient in ventilated area
• Avoid crowded places
• Use mask outside

🔴 SUMMARY POINTS

1. Disease - condition where body doesn't function properly
2. Types: Communicable (spread) and Non-communicable (don't spread)
3. Communicable diseases cycle: Infected person → Pathogens → Mode of transmission → Susceptible person → New infection
4. Modes of transmission: Direct contact, airborne, food/waterborne, vector-borne, blood-borne, sexual, mother to child
5. Food/waterborne diseases: Roundworm, Diarrhea, Dysentery, Cholera, Typhoid
6. Airborne diseases: Common Cold, TB, Flu
7. Blood-borne diseases: Hepatitis B, C, HIV
8. Vector-borne diseases: Malaria, Dengue, Japanese Encephalitis
9. Non-communicable diseases: Cancer, Heart Disease, Diabetes, Asthma
10. Cancer - uncontrolled cell growth; caused by physical, chemical, biological factors
11. Heart diseases - leading cause of death; prevented by healthy lifestyle
12. Diabetes - glucose metabolism disorder; requires lifelong management
13. Asthma - chronic lung disease; triggered by allergens, smoke, pollution
14. Cholera - acute diarrheal disease; prevented by clean water and hygiene
15. Dengue - mosquito-borne viral disease; prevented by mosquito control
16. Viral Influenza - respiratory infection; spreads through droplets

🔑 KEY DEFINITIONS

💡 EXAM TIPS

• For definitions: Memorize key terms exactly as given
• For classification: Remember 2 types with 5 examples each
• For disease cycle: Practice drawing and labeling
• For transmission modes: Remember 8 modes with examples
• For specific diseases:

1. Cause (pathogen name)
2. Transmission mode
3. Symptoms (minimum 5)
4. Prevention (minimum 5)

• For Hepatitis B: Special focus on transmission and prevention
• For Cancer: Remember 7 symptoms and 8 prevention measures
• For Heart Disease: Differentiate Heart Attack and Brain Stroke
• For Diabetes: Remember symptoms and prevention
• For Dengue: Focus on mosquito breeding sites and prevention

🧠 MEMORY TRICKS

8 Modes of Transmission: "DAC V-BMS" - Direct contact, Airborne, Contact, Vector, Blood-borne, Mother to child, Sexual

5 Food/Waterborne Diseases: "RCDTD" - Roundworm, Cholera, Diarrhea, Typhoid, Dysentery

3 Blood-borne Diseases: "HBH" - Hepatitis B, Hepatitis C, HIV

4 Major NCDs: "CHDA" - Cancer, Heart disease, Diabetes, Asthma

5 Cancer Prevention: "HALTS" - Healthy diet, Avoid tobacco, Look for symptoms, Treatment early, Safe environment

Heart Attack Symptoms: "CPSS" - Chest pain, Pain in arm, Sweating, Shortness of breath

Dengue Prevention: "4Cs" - Clean surroundings, Cover water, Containers disposal, Clothes (full sleeves)

📊 IMPORTANT DATA

• Cancer deaths annually: 56 lakh (expected 1.14 crore by 2030)
• Heart disease deaths annually: 1.75 crore
• Diabetes patients worldwide: 18 crore
• Asthma patients worldwide: 8 crore
• Hepatitis B deaths annually: 20 lakh
• Cholera discovery year: 1883 (Robert Koch)
• First Dengue Epidemic in Nepal: 2016