Health And Diseases: Types, Causes, Symptoms, Prevention And Deficiency Disorders

Health does not only mean the absence of illness.

It is a complete state of physical, mental and social well-being.

A healthy person is able to function properly, respond to changes in the surroundings and maintain balance inside the body.

Health is also a dynamic state. It keeps changing with food habits, hygiene, lifestyle, environment and immunity.

Pillars Of Good Health

Good health depends on basic daily habits.

• Balanced Diet – provides nutrients needed for growth, repair and energy.
• Personal Hygiene – helps prevent infections.
• Regular Physical Activity – keeps the body active and strong.

What Is Disease?

A disease is a condition in which the normal functioning of the body is disturbed.

Diseases may occur due to:

• Pathogens such as bacteria, viruses, protozoa and fungi.
• Genetic factors inherited from parents.
• Nutritional deficiencies caused by lack of essential nutrients.
• Environmental factors such as polluted water, harmful chemicals and poor sanitation.

Types Of Diseases

Diseases are broadly divided into:

• Communicable diseases
• Non-communicable diseases

Communicable Diseases

Communicable diseases are infectious diseases that spread from an infected person to a healthy person.

They are caused by pathogens.

Modes Of Transmission

Mode	Example
Air	Tuberculosis
Water	Cholera
Vectors	Malaria, Dengue
Direct Contact	Syphilis, Gonorrhoea

Bacterial Diseases

Bacterial diseases are caused by bacteria.

Important Bacterial Diseases

Disease	Causative Agent	Transmission	Key Symptoms	Prevention / Treatment
Tuberculosis	Mycobacterium tuberculosis	Droplets	Fever, cough, chest pain, weight loss	BCG vaccine, isolation, antibiotics
Diphtheria	Corynebacterium diphtheriae	Droplets	Sore throat, mild fever	DPT vaccine
Whooping Cough	Bordetella pertussis	Droplets	Severe cough, inspiratory whoop	DPT vaccine, antibiotics
Tetanus	Clostridium tetani	Wound infection	Lockjaw, muscle spasms	Anti-tetanus serum
Cholera	Vibrio cholerae	Contaminated food and water	Watery stool, vomiting, dehydration	ORS, sanitation
Typhoid	Salmonella typhi	Contaminated food, water, flies	Step-ladder fever, intestinal ulcers	Antibiotics, Widal test
Leprosy	Mycobacterium leprae	Prolonged close contact	Skin patches, numbness, deformities	Multidrug therapy
Plague	Yersinia pestis	Rat flea	Painful buboes, high fever	Antiplague vaccine, vector control

Viral Diseases

Viral diseases are caused by viruses.

Important Viral Diseases

Disease	Causative Agent	Transmission	Key Symptoms	Prevention / Treatment
Measles	Rubeola virus	Droplets	Skin rash, fever	MMR vaccine
Mumps	Mumps virus	Droplets	Swelling near jaw, fever	MMR vaccine
Smallpox	Variola virus	Contact, droplets	Pustules, scabs	Eradicated globally
Chickenpox	Varicella zoster	Contact	Fluid-filled vesicles, fever	Varicella vaccine
Polio	Poliovirus	Contaminated food/water	Paralysis	OPV, IPV
Influenza	Myxovirus influenzae	Air	Fever, sore throat, body pain	Hygiene
Rabies	Rhabdovirus	Bite of rabid animal	Hydrophobia, brain damage	Rabies vaccine
Dengue	Dengue virus	Aedes mosquito	Fever, joint pain, low platelets	Mosquito control
Hepatitis	HAV, HBV, HCV, HDV, HEV, HGV	Polluted water, faecal-oral route, blood	Jaundice, dark urine, liver swelling	Clean water, hygiene
AIDS	HIV	Sexual contact, blood, mother to child	Weight loss, fever, diarrhoea, low immunity	Antiretroviral drugs

Important Fact About AIDS

AIDS stands for Acquired Immuno Deficiency Syndrome.

It is caused by HIV, a retrovirus.

World AIDS Day is observed on December 1.

Helminthic Diseases

Helminthic diseases are caused by worms.

Disease	Causative Agent	Transmission	Symptoms	Prevention
Ascariasis	Ascaris lumbricoides	Dirty hands, raw vegetables, contaminated soil	Abdominal pain, cough, nausea	Sanitation, antihelminthic drugs
Taeniasis	Taenia solium	Improperly cooked food	Indigestion, loss of appetite	Properly cooked food
Filariasis	Wuchereria bancrofti	Culex mosquito	Swollen legs, elephantiasis	Mosquito control

Protozoan Diseases

Protozoan diseases are caused by protozoa.

Disease	Causative Agent	Vector / Transmission	Symptoms	Prevention / Treatment
Malaria	Plasmodium species	Female Anopheles mosquito	Fever, chills, sweating	Mosquito nets, repellents, antimalarial drugs
Amoebiasis	Entamoeba histolytica	Contaminated food and water	Diarrhoea, blood and mucus in stool	Sanitation, hygiene
Kala-azar	Leishmania donovani	Sandfly	Irregular fever, enlarged spleen and liver	Avoid sandfly bites
Sleeping Sickness	Trypanosoma gambiense	Tse-tse fly	Fever, lethargy, unconsciousness	Fly control

Fungal Diseases

Fungal diseases are also called mycoses.

Disease	Causative Agent	Transmission	Symptoms	Prevention / Treatment
Ringworm	Microsporum, Trichophyton, Epidermophyton	Contact with infected persons or animals	Reddish sores, blisters	Hygiene, antifungal treatment
Aspergillosis	Aspergillus fumigatus	Inhalation of spores	Cough, fever, chest pain	Avoid dusty areas, antifungal drugs
Fungal Meningitis	Cryptococcus neoformans	Inhalation of spores	Headache, stiff neck, fever	Antifungal treatment
Athlete’s Foot	Tinea pedis	Damp public areas	Itching, rash between toes	Keep feet dry, antifungal powder

Non-Communicable Diseases

Non-communicable diseases do not spread from person to person.

They may be caused by lifestyle, heredity, metabolism or uncontrolled cell growth.

Diabetes

Diabetes is a long-term condition caused by excess glucose in the blood.

Types Of Diabetes

• Type 1 Diabetes – body does not produce enough insulin.
• Type 2 Diabetes – body produces insulin, but cells do not respond properly.

Symptoms Of Diabetes

• Excessive thirst
• Frequent urination
• Tiredness
• Weight loss
• Loss of muscle bulk

Cancer

Cancer is the uncontrolled growth of abnormal cells.

Normal cells may become tumour cells due to uncontrolled mitotic division.

Cancer-causing agents are called carcinogens.

Causes Of Cancer

• Physical agents
• Chemical agents
• Biological agents
• Tobacco smoke
• Oncogenic viruses

Blood Cancer

Blood cancer is called leukaemia.

It is diagnosed using blood tests, bone marrow tests, biopsy and histopathological studies.

Genetic Disorders

Genetic disorders are caused by abnormalities in the genome.

Autosomal Recessive Disorders

Disorder	Cause / Description	Key Symptoms
Albinism	Inability to produce melanin	Lack of normal skin colour
Thalassemia	Low haemoglobin and fewer RBCs	Poor oxygen transport
Phenylketonuria	Deficiency of phenylalanine hydroxylase	Mental retardation, abnormal skin and urine colour
Sickle Cell Anaemia	Valine replaces glutamic acid in beta-chain of haemoglobin	Sickle-shaped RBCs

X-Linked Disorders

Disorder	Description
Haemophilia	Blood clotting does not occur properly due to deficiency of Factor VIII
Colour Blindness	Inability to distinguish red and green colours

Haemophilia is also called the Royal Disease because it appeared in European royal families.

Y-Linked Disorder

Disorder	Feature
Hypertrichosis	Excessive hair on ear pinna

Chromosomal Disorders

Disorder	Chromosomal Condition
Down Syndrome	Trisomy of chromosome 21
Turner Syndrome	44 + X0
Klinefelter Syndrome	44 + XXY

Nutritional Deficiency Diseases

Nutritional deficiency diseases occur when the body does not get enough essential nutrients.

Protein Energy Malnutrition

Disorder	Common In	Symptoms
Kwashiorkor	Children	Retarded growth, oedema, slender legs, bulging eyes
Marasmus	Infants under one year	Weak body, wrinkled skin, thin limbs, weight loss

Vitamins And Deficiency Diseases

Vitamins are accessory food factors required in small quantities.

They do not provide energy, but they are essential for metabolism and body function.

Vitamins were discovered by Funk in 1912.

Types Of Vitamins

• Fat-soluble vitamins – A, D, E and K
• Water-soluble vitamins – B-complex and C

Vitamin Deficiency Table

Vitamin	Deficiency Disease
Vitamin A	Night blindness, Xerophthalmia
Vitamin B1	Beri-Beri
Vitamin B2	Cheilosis, Glossitis
Vitamin B3	Pellagra
Vitamin B6	Anaemia, Convulsions
Vitamin B7	Hair loss, Anaemia, Fatigue, Dermatitis
Vitamin B9	Megaloblastic anaemia
Vitamin B12	Pernicious anaemia
Vitamin C	Scurvy
Vitamin D	Rickets in children, Osteomalacia in adults
Vitamin E	Sterility in rare cases, neuromuscular degeneration
Vitamin K	Blood clotting disorder, haemorrhage

Key Takeaways

• Health includes physical, mental and social well-being.
• Diseases may be communicable or non-communicable.
• Communicable diseases are caused by pathogens and spread through air, water, vectors or contact.
• Bacterial diseases include TB, cholera, typhoid, tetanus and leprosy.
• Viral diseases include measles, polio, rabies, dengue, hepatitis and AIDS.
• Protozoan diseases include malaria, amoebiasis, kala-azar and sleeping sickness.
• Diabetes and cancer are non-communicable diseases.
• Genetic disorders may be autosomal, sex-linked or chromosomal.
• Deficiency of vitamins causes specific diseases.

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