Human Physiology, Diseases, Tuberculosis, Prevention and Control

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Human Physiology, Diseases


Causal organism: Salmonella typhi

Mode of Spread

  • By contaminated food and water.
  • By faeces and urine of the patient.
  • By direct contact with patient.


Since the incubation period of the bacteria is 10 - 14 days therefore symptoms of disease will appear after 10 - 14 days of infection. Various symptoms of disease are:

  • High fever.
  • Slow pulse.
  • Tender and distended abdomen.
  • Eruption of rose-coloured rashes on body.
  • Diarrhoea with water-green stools.


  • Causal organism: Mycobacterium tuberculosis
  • Tuberculosis is most common in crowded city slums. Bacterium which causes tuberculosis can infect any organ of body, but the most favourite site is lung. It can also attack lymph nodes, bones and joints.

Mode of Spread

  • By inhalation of droplets of infected sputum expelled by patient during coughing, sneezing or speaking.
  • By contaminated food, water or milk.
  • By inoculation of bacteria into the skin or mucus membrane.


  • Constant fever.
  • Pain in chest.
  • Cough and blood in sputum.
  • Loss in body weight.
  • Gradual weakening of body.

Prevention and Control

  • Isolation of patient.
  • The B. C. G. vaccine against tuberculosis gives considerable protection against disease.


Causal organism: Macrobacterium leprae

Mode of Spread

By prolonged contact with diseased parts of patient.


  • Appearance of light-coloured patches on the skin.
  • In acute cases the organs are deformed, and parts of body are lost.
  • Perpheral nerves are damaged therefore affected organ becomes senseless.
  • Ulcers, nodules, scaly scabs and deformities of toes and fingers may also be caused.


Causal organism: Neisseria meningit

Mode of Spread

By coughing and sneezing the germs spread from infected person to healthy person.


  • Sore throat, fever, severe headache.
  • Vomiting.
  • Difficulty in bending the head to forward due to stiffness of neck.
  • Occasional appearance of red spots all over the body surface.
  • The clear cerebrospinal fluid becomes turbid due to inflammation of meanings (membranes covering the brain and spinal cord) also called meningitis.


It is called venereal disease.

Mode of Spread

  • Through intercourse with an infected man.
  • They enter the body through any crack or cut in the skin.
  • Through contaminated objects.


  • Occurrence of fever and skin eruptions.
  • After 3 - 4 weeks of infection, the primary sore or pimple appears on external genitals (the penis in male and labia minora and majora in female) which gradually become big and hard and later on becomes more prominent.
  • Enlargement of lymph nodes in groin takes place.
  • after 2 - 3 months, white shiny patches appear inside the mouth.
  • Eruption appears on the skin particularly on face, palms, soles and scalp.
  • Destructive changes in the internal organs of the body take place even after many years.
  • Cardio vascular system may be badly affected.
  • The infection can pass from infected pregnant mother to developing foetus through placenta and may result in the premature death of the foetus.

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