Biology Revision Notes Of Human Health and Diseases For NDA


Health is a state of complete physical, mental and social well- being. It is the functional or metabolic efficiency of a Jiving being. Some basic factors such as balanced diet, personal hygiene and regular exercise contributes to good health. Apart from these, awareness about diseases and organisation, etc., also affects health.


Disease a condition of disturbed m· nagged functioning of the body due to infection, detective diet, heredity and environment. The causes of in humans can be pathogens, genetically, etc. Different types of diseases are categorised as follows

Communicable Diseases

There are usurious kinds of communicable disburses, which affect the health of human brings. Tb.:~e diseases are infectious, i.t:. they spread from affected individual to normal individual. These are caused t.y pathogens such as arterial, virus, Protozoa and fungi. These pathogens the disease by means of air, water vectors or sexual contact.
Some of them are as follows

Bacterial Diseases

Following diseases are caused by bacteria.

`text(1. 'Tuberculosis (TB))`
• It is caused by Mycobtcterium tuberculosis (gram positive).
• It spreads through coughing, sneezing, talking and splitting droplets. Symptoms of this disease are fever, cough, sputum with blood, chest pain, loss of appetite, weight loss.
• It can be persevered by immunization that includes BCG (Bacillus Calmette Guerin) vaccine, isolation of patient, sanitation, etc.
• Antibiotics such :ls rifampicin, isoniazid, etc.

`text(2. Diphtheria)`
It is caused by Corynebactcnmn diphtheriae (gram positive).
• Infection occurs through droplets.
• It is characterised by slight fever, oozing of semisolid materiel in throat (sore throat).
• Immunisation is done with DPT vaccine.

`text(3. Pertussis/Whooping Cough)`

• It is caused by Bacillur pertussis or Bordetella pertussis
(gram negative).
• infection occurs through direct contact and droplets, characterized by inflammation of npiratory passage, cold,
cough and mild fever in beginning leading to accumulation of mucus and inspiratory whoop.

Van:ination is done with DPT (Diphtheria), pertussis and Tetanu), use of antibiotic drugs like erythromycin, chloramphenicol and ampicillin.

`text(4. Tetanus /lock Jaw Disease (Dhanustamba))`

• It is caused by Clostridium tetani (rod-shaped, gram positive). Its infection occurs through spores of bacteria entering into body via wounds, accidents and unsterilised surgical instruments as this bacterium secretes tetanospasmin toxin.
• It is characterised by muscular rigidity (lock jaw) and painful muscular spasm.
• Injection of ATS (Anti Tetanus Serum) within 24 hours of injury leads to protection against this disease.

`text(5. Cholera)`

• It is caused by Vibrio cholerae.
• It spreads through contaminated food and water or by direct contact.
• 1 t is characterised by effortless watery stool, vomiting, rapid dehydration, muscular cramps.
• It is treated by use of ORS (Oral Rehydration Solution) and sanitation.
• ORS contains (1L) 1.5 g glucose, 3,5 g NaCl, 2.9 g KCl and 12.9 g trisodium citrate.

`text(6. Diarrhoea)`

• It is caused by Salmonella typhimurium (salmonellosis) and Shigella shigt'Je (shigellosis).
• It spreads though contaminated meat and other proteinaceous food articles and transmitted through fingers, beds, clothes and utensils and most importantly by faeces.
• Vomiting, nausea, headache, paratyphoid fever and frequent passage of stool with mucus, blood and abdominal cramps are symptoms.
• Oral and intravenous rehydration is required for treatment.

`text(7. Pneumonia)`

• It is caused by Diplococcus pneumonlae or Streptococcus pneumoniae (gram positive).
• It transmits through droplets (sputum).
• Symptoms are sudden chill, chest pain, cough with rusty mucoid sputum and rise in temperature.
• It is treated by uses of drugs like erythromycin, tetracycline and penicillin.

`text(8. Syphilhs)`

8. Syphilhs
It is caused by Treponema pallidum (a spirochatte).
• It transmits through sexual contact and from mother to children. Common symptoms are painless ulcer on the genitals and swelling of local lymph glands, rashes, hair loss, swollen joints and flu-like illness.
• Disease is curable through appropriate antibiotics, e.g. penicilli.n and tetracycline.

`text(9. Gonorrhoea)`

• It is caused by Neisseria gonorrhoeae or Diplococcus gonorrboeae.
• It spre;tds through sexual contact, common toilets and under clothes. Bacterium lives in genital tubes, produces pus containing discharge, pain around genitalia and burning sensation during urination.
• Use of antibiotics, e.g. penicillin, ampicillin and maintain high moral characters.
• It is Venereal Disease (VD) or Sexually Transmitted Disease (STD).

`text(10. Plague/Bubonic Plague (Black Death))`

• This disease is caused by Yersinia pestis or Pasturella pastis.
• It spreads through rat flea (Xenopsylla cheopis) to man.
• Symptoms are armpit and groin swell up into painful buboes, high-fever, chill, exhaustion and haemorrhages, which turns black.
• Treatment with antiplague vaccine
spraying of pesticides killing of rats.
• Wayson stain test is performed for diagnosis of this disease.

`text(11. Typhoid)`

• It i:; caused by Salmonella typhi.
• It spreads through food, milk and water contaminated with intestinal discharge· either directly or through housefuls.
• High fever in steps, lesions and ulceration in the intestinal wall are common symptoms. Use of antibiotics (ampicillin and chloramphenicol), prolonged treatment is required for this disease.
• `text(Widal test)` is performed for diagnosis of this disease.

`text(12. Leprosy (Hansen's Disease)`
• It is caused by Mycobacterium leprae.
• It does not spread by initial contact, but prolonged closer contact through skin lesions, nasal and throat discharges also spreads this disease.
• Sanitatton and use of suitable drugs like dapsone, rifampicin, ofloxacin and chaulmoogra oil along with surgery may protect from the disease.
• can enter into the body and damage nerves, skin, lymph nodes, eyes, nose, mouth, larynx, muscles , spleen, etc.

• Appearance of skin patches, numbness in some body parts, fever, finally ulcer, nodules, lesions, scaly scabs, deformities in finger, toes and wasting of body parts are symptoms.

`text(13 Botulism)`
• It is caused by Clostridium botulinum.
• Symptoms arc double vision, blurred vision, drooping eyelids, slurred speech, difficulty in swallowing, dry mouth and muscle weakness.
• It spreads through contaminated food and water or food stuffs product.
• To remove the source of toxin producing bacteria, the administration of proper antibiotics are used.

VIRAL Diseases

Following diseases arc caused by viruses

`text(1. Measles (Khasra))`
• It is caused by Rubeola virus/ poynosa morbillormn. It is transmitted by contact, fomite or droplet methods.
The virus enters through respiratory tract and conjunctiva. It is characterised by itching, skin rash, small raised red spot in crescent-shaped groups starting from had, of cars and reaching to forehead, face and then on whole body.
• Antibiotics and vitamin-A are given to prevent complications. Vaccination MMR (Mumps, Measles, Rubella) is given at the age of one.

`text(2. Mumps)`

• It is caused by Paramyxo or Mumps virus
• It is transmitted by direct contact, droplet.
• In this disease, patient feels difficulty in swallowing and opening of mouth.
• Its symptoms arc high fever chills beachcomber, general boneheads and loss of appetite.
• Treated by vaccination with MMR.

`text(3. Smallpox (Chechuk))`
• It caused by Variola virus.

`text(4. Chickenpox)`
• It is caused by Varicella zoster with incubation period of 14-16 days.
• It is a contagious disease that occurs in winter and springs.
• Presence of pro dermal rashes with crops of pinkish centripetal spots first on trunk, forehead and face.
•Uneasiness, aches and high fever accompany each new crop. Spots turn into fluid-filled vesicles and then scabs.
• Scabs fall off without leaving any mark.
• No drugs and no vaccines, only use of borie acid and calamine reduces itching problem.

`text(5. Polio /Infantile Paralysis)`

It is caused by Polio virus or Entero virus.
• Highly infectious disease of infant and children.
• Transmitted through faeces, urine and nasal secretions contaminating food, water, drinks, either directly or through
flies with an incubation period of 5-17 days.
• It produces inflammation of the nervous system causing inability to bend the head forward. Paralysis starts following the weakness of particular skeletal muscles.
• Polio is preventive.
• Salk's vaccine (now Sabin's oral) is available for taking at the age of 6 weeks, 10 weeks, 14 weeks and booster dose at 18-24 months.
The Hoff kine Institute of Mumbai is known for the production of polio vaccine.

`text(6. Influenza / Flu)`

• It is caused by H aemophilus influenzae or Afyxovims influenzae.
• It spreads by the entering of contaminated air into respiratory tract.
• It starts with fever, headache, sore throat, cold with sneezing and pain all over the body with restlessness.
• No vaccine, hygiene and sanitation.

`text(7. Rabies I Hydrophobia)`

• It is caused by Rhabdo virus.
• It is transmitted to human beings by bitting saliva of rabid (mad) dog or cat.
• Jackals, wolves, foxes, mongoose and bats also have rabies virus.
• Initial symptoms of rabies are excessive saliva from mouth, severe headache, high fever, depression and inability to swallow even fluids due to choked throat. Fear of water, i.e. hydrophobia is most important characteristic.
• The virus destroys the brain and spinal cord. Bitten person should be immediately
administered vaccine (earlier 14 . inoculations but now 6 doses of vaccines) are recommended.
• Dog should be watched for 10 days for the development of rabies symptoms (running amuck, change of voice and excessive salivation).

`text(8. Dengue Fever)`

• It is caused by DEN-1-4 virus and transmitted by female Tiger mosquito (Aedes aegypti). .
Its symptoms are headache, fever chill, pain in joints and skin rashes. More severe in adults.
• In this disease, blood platelets number falls below 70000/mm 3
• Paracetamol with replenishment of blood platelets may be helpful.

`text(9. Hepatitis)`

• It is commonly called jaundice.
• Jaundice is the result of incomplete metabolism of bilirubin pigment of wornout RBCs.
• Its infection spreads through faecal-oral route and polluted water.

`text(10. AIDS)`
• Acquired Imrnuno Deficiency Syndrome (AIDS) is a disease of human immune system.
• It is caused by Human Immunodeficiency Virus (HIV).
• HIV is a lentivirus of the retrovirus family.
• HIV can spread by the following methods
(i) Through sexual contact, e.g. oral, vaginal and anal sex.
(ii) Through blood transfusions, e.g. accidental needle sticks or needle sharing.
(iii) From mother to child, e.g. a pregnant woman can transmit virus to her foetus through their shared blood circulation or a nursing mother can pass it to her baby through breast's milk.
• Major clinical symptoms of AIDS in humans are loss
of weight, prolonged fever, chronic diarrhoea, red or brown blotches on or under the skin of nose, mouth.
swallon gland,. fatigue, etc.
• In children less then 12 years of age, persistent cough is not a. clinical symptom of AIDS.
• ELISA, PCR and RIP /IF A are the confirmatory tests for AIDS.
• Anti-retroviral drugs, e.g. AZT (Azidothymidine), zidovudine and norvir are used to supress AIDS.
• AIDS day is observed on 1st December.

`text(11. Yellow Fever)`
• It is caused by Flavi virus.
• The mosquito Aedes aegypti transmits the virus to humans.
• Its symptoms are aching muscles particularly the back and knee muscles, dizziness, loss of appetite, nausea, shivers (chills) and vomiting. Skin and whites of eys take a yellow ·tinge.
• No effective antiviral medication, but making sure the patient's blood pressure is adequate, replacing lost blood and treating any secondary infections.
• This disease is not prevalent in India.

`text(12. Chikungunya)`
• It is caused by Alphavirus and spreads by Aedes mosquito.
• The symptoms are fever, joint pain, swelling and rashes.
• It can be prevented by checking mosquito populations.
• No such treatment apart from nracetamol and anti inflammatory drugs.

`text(13. Swine Flu)`

• It is caused by H1N1 virus.
• It is also called hog flu or pig influenza.
• The risk of this disease is higher in those, who consume pork.
• Symptoms are fever, lethargy, sneezing, coughing, difficulty in breathing and decreased appetite.
• Tamiflu and relenza vaccine an: used to prevent this disease.
• There is absence of an effective treatment or vaccine for swine flu.

Helminthic Diseases

These diseases are caused by helminthic worms. Some helminthic diseases are.

`text(1. Ascariasis)`
• It is caused by Ascaris lumbricoides.
• It spreads through raw vegetables, dirty hands and ingestion
of contaminated soil.
• Its symptoms are nausea, cough and severe abdominal pain.
Intestinal destruction may also occur.
• Preventive measures includes sanitation and uses of antihelminthic drugs.

`text(2. Taeniasis)`
• It is caused by Taenia sodium.
• It spreads through improperly cooked food and also through raw vegetables, which are not properly washed.
• The symptoms are chronic ingestion, anorexia, similar symptoms of epilepsy.
• Treated by sanitation, use of properly cooked food and helminthic drugs.

`text(3. Filariasis)`
• It is caused by Wuchereria bancrofti.
• Transmitted by Ctdex sp. of mosquito.
• Fever, legs may become swollen and resemble with those of elephant. So, this disease is also called elephantiasis.
• The preventive measures includes destruction of mosquitoes and use of mosquito repellent :reams and mats and antihelminthic drugs.

Protozoan Diseases

These diseases are caused by protozoans. Some protozoan diseases are.

`text(1. Malaria)`

• It is caused by Plasmodium species. It affects several body parts like liver (initial multiplication), RBCs, spleen and brain. But it does not affect kidney. It shows multiplication in liver. Plasmodium has two hosts
(i) Female Anopheles mosquito (definitive or primary host) present in the saliva of mosquito.
(ii) Human beings (intermediate or secondary host).
• Plasmodium vivax
(i) It causes benign tertian malaria.
(ii) Most common in India.
• Plasmodium falciparum
(i) It causes cerebral malaria.
(ii) Common in certain parts of India.
• Plasmodium ovale
(i) Rarest species, which infects man.
• Plasmodium malariae
(i) Common in tropical Africa, Burma, Sri Lanka and parts of India.
(ii) i;e of mosquito nets, repellent creams and mats, use of chloroquine, primaquine tablets may prevent malaria.
(iii) Most effective medicine for malaria is quinine (obtained from cinchona tree).

`text(2. Amoebiasis / Amoebic Dysentry)`
• It is caused by Entamoeba histolytica (an endoparasite).
• Parasite lives in the large intestine of humans.
• Infection occurs by ingesting cysts with food and water.
• The symptoms are mild diarrhoea, presence of mucus and blood in stool and abdominal pain.
• Proper sanitation and personal hygiene is useful for protection. Antiamocbic drugs are used for protection.

`text(3. Leishmaniasis)`
• It is commonly called as kala-azar.
• It is caused by Leishmania donovani. It multiplies by multiple fission.
• Spreads by sandfly (Phlebotomus) bite.
• The symptoms often resemble malaria with irregular recurrent fever and leukopenia with enlargement of spleen and liver.

`text(4. African Sleeping Sickness (Trypanosomiasis)`
• It is caused by Trypanosoma gambiense.
• The parasite is trammitted by blood sucking tse-tse fly (Glossina palpdis ).
• Parasite lives in blood plasma.
• Fever with glandular swelling.
• In acute condition, parasite enters into cerebrospinal fluid and damage the brain. It makes the patient lethargic and unconsiuos
• Prevention is done by eradicating from flies and shrubs.

Fungal Diseases

Fungal diseases are also called mycoses. Mycoses are common in human as well as in animals. One of them is.

• It is caused by Microsporum.
• It spreads by unbathed cats, dogs or infected persons.
• In this disease,. sores are formed, which become reddish and contain blisters,
• Treated by proper sanitation and hygiene.
• Some other fungal diseases with their causative agents are aspergillosis (Aspergillus fumigatus), meningitis (Cryptococcus neoformans), dermatitis of beard and hair (Trichophyton verrucosum) and athlete's foot (Tinea pedis).


There are variows kinds of non-communicable diseases, which affect the health of human beings. Some of the common non communicable diseases are

`text(1. Diabetes)`

• Diabetes is a long-t<:rm condition caused by too much glucose (sugar) in the blood.
• There are two main types of diabetes
(i) Type 1 diabetes occurs when the body does not produce enough insulin to function properly or the body's cells do not react to insulin. This is known as insulin resistance.
(ii) Type 2 diabetes is far more common than type 1 diabetes, which occurs when the body does not produce any insulin at all. Type 2 diabetes usually affects people over the age of 40.
• Symptoms are feeling very thirsty, urination frequently particularly at night, feeling very tired, weight loss and loss of muscle bulk.

`text(2. Cancer)`
• It is the uncontrolled growth of abnormal cells in the body.
• Cancer occurs when normal cells due to uncontrolled mitotic division arc converted into tumour cells.
• The resulting uncontrolled growth forms masses of cells called tumour. Cancerous cells arc also called malignant cells.
• Symptoms of cancer depend on the type and location of the cancer.
• These arc induced by physical, chemical and biological factors or agents. The agents causing cancer arc called carcinogens or cancer causing agents.
• Tobacco smoke contains chemical carcinogens that cause lung cancer.
• Viruses also cause cancer. These are called oncogenic vimses as they have genes called viral oncogenes.
• Leukaemia or blood cancer can be detected based on biopsy and histopathological studies of the tissue and blood and bone marrow tests for increased cell counts.
Cancer thcrapies are
(i) Cryo surgery (ii) Proton therapy
(iii) Radiation therapy
(iv) Stem cell transplantation (also involved in spinal injury cure)
(v) Peripheral Blood Stem Cell Transplantation (PBSCT)


A genetic disorder is an illness caused by one or more abnormalities in the genome. These may be of three types.

`text(1. Autosomal Recessive Disorders)`

These arc as follow
(i) Albinism This disesase is caused due to inability to produce melanin pigment. It is characterised by absence of normal colouration of the skin.
(ii) Galactosaemia This is due to defect in galactose mctabolim. They may causes mental retardation.
(iii) Phenylketonuria It occurs due to the deficiency of an enzyme phenylalanine hydroxylase, which converts phenylalanine into tyrosine. Symptoms are mental retardation, typical colour of skin and urine.
(iv) Alkaptonuria In this metabolic disorder, there is absence of homogentisic acid oxidase, which oxidiscs homogentisic acid. The urine of such patients darkens on exposure.
(v) Sickle-cell Anaemia It is a genetic disorder. It is characterised by RBCs of paticnt(individuals) become elongated and curved to become sickle-shaped in `O_2` deficiency. In defective haemoglobin, the glutamin amio acid at 6th place of !)-chain of Hb is replaced by valine.

`text(2. X-Linked Recessive Disorders)`
Genes arc located in the differential segments of X-·chromosome. These are as follow 809
(i) Haemophilia Haemopbilia appeared in several interrelated Royal families of Europe, apparently arising from a mutation in one parent of Queen
Victoria of England (1819-1901), hence is called 'Royal disease'. In this disorder, blood coagulation docs not take place. It is due to deficiency of Factor VIII (antihacmophilic factor).
(ii) Colour Blindness This disease is also known as Daltonism. Affected person cannot distinguish between green and red colour. Colourblind persons cannot service in Railway department.

`text(3. Y-Linked Rec,essiive Disorders)
• Hypertrichosis, i.e. excessive hairs on ear pinna is a Y -linked recessive disorder.


• The principle of vaccination and immunisation is based upon the 'memory' of immune system.
• In vaccination a preparation of inactivated or weakened pathogen (vaccine) arc introduced into the body. The antibodies are produced against these antigen would neutralise the pathogenic agents during actual infection. The vaccine also generate memory B and T-cells that recognise the pathogens quickly on subsequent exposure and act against them with a massive production of antibodies.
• Edward Jenner discovered the first vaccine.
• Pasteur invented the vaccine for rabies.
• Robert Koch discovered anthrax bacteria.
• Penicillin was discovered by Sir Alexander Flemming from Penicillium ftngus.


The ability of a host to defend itself from most of the foreign agents is called as immunity. The parts of body that act together to achieve immunity together constitute the immune system. lmmunology is the branch of science that studies the immunity. Emil von Behring considered to be the father of immunology.

Types of Immunity

Immunity Is of two types
`text((i) I n n a t e Immunity)` It is non-specific and present at the time of birth.
`text((ii) Acquired Immunity)` It is pathogen specific and characterised by memory. There are two types of immune systems found in our body. One is humoral and other is cell mediated. B-lymphocytes produce antibodies and T -cells help them in this process. The response provided by antibodies IgA, IgM, IgE, IgG and IgD present in blood is called humoral immune response (antibody-mediated).
The second type is called cell mediated immune response or cell mediated immunity (CMI). The T-cells mediate CMI.

Health Organisations

Some health organisations are as follows
(i) World Health Organisation It was established in 1948.
(ii) Red-Cross It was founded in 1864. The emblem of
red-cross is a red-colored 'plus'.
(iii)United Nations International Emergency Funds (UNICEF). Iv; an organisation of UNO.