Keeping diseases away is an interesting chapter of kerala sslc biology examination.In this section we provide notes,pdf,questions of this chapter as table wise

Modes of transmission of diseases

  • By contact
  • Contaminated food and water
  • Unsterilized equipments
  • Vectors
  • through body fluids
  • through air


Rat fever (Leptospirosis)

Pathogenbacterial disease-Leptospira
Mode of transmissionbacteria that comes out through the urine of rat, dog and certain other animals remain alive in stagnant water and moisture,bacteria reach blood through wounds
mode of affectionThe toxins produced by the bacteria destroy cells and cause disease.
symptomsSevere fever, headache, muscle pain, redness in eyes


pathogenbacteria Corynebacterium diphtheriae
mode of transmissionspreads through cough, sneezing or directly from the
infected person to another person
mode of affectionToxins produced by the bacteria cause fever, throat
pain and inflammation in the lymph glands of the throat
symptomsash coloured thick coating in thethroat within two or three days.Gradually brain, heart and kidneys are affected.throat pain


PathogenMycobacterium tuberculosis
mode of transmissionWhen the patient speaks, coughs or sneezes, the pathogens spread into the air and thereby to others.
SymptomsLoss of body weight, fatigue, persistent cough
Organs/Body parts Affectedmainly affects the lungs. But kidneys, bones,joints, brain etc. are also affected by this disease
TreatmentBy administering antibiotics


AIDS (Acquired Immuno Deficiency Syndrome)

PATHOGENHuman Immuno deficiency Virus
MODE OF TRANSMISSIONThrough sexual contact with HIV infected person
From HIV infected mother to the foetus
By sharing needle and syringe contaminated with HIV components
Through the reception of blood and organs contaminated with HIV
METHOD OF AFFECTIONreduces the immunity of the body.


PATHOGENHepatitis virus
mode of transmissionDisease gets transmitted through contaminated food and water, blood components and excreta of the patient
major symptomInflammation of the liver,dark yellow colour to the mucus membrane, white portion of the eyes and the nails

Fungal Diseases

The toxins produced by the fungi cause diseases.


pathogenfungi(ring worm)
affected partskin
symptomsmanifests as round, red blisters on the skin
spreadthrough contacts

Athletes’ foot

affected partthe sole of the foot
and between the toes.
symptomsitching is the major symptom.
Appear as reddish scaly rashes
spreadPathogens enter through the toes when they
come in contact with contaminated water and soil.

Disease caused by parasites[protozoan diseases]


VectorFemale Anopheles mosquito
symptomsHigh fever with shivering and profuse sweating
headache, vomitting, diarrhoea, anaemia,


Pathogen-filarial worms
vectorCulex mosquitoes
symptomsThe worms stay in the lymph ducts and obstruct the
flow of lymph by blocking the ducts. This causes swelling in the lymph ducts.


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