61• Health is a state of optimum physical fitness, mental maturity and social well being.
• A disease is a particular abnormal, pathological condition that affects part or all of an organism. It is
often construed as a medical condition associated with specific symptoms and signs.
• In humans, “disease” is often used more broadly to refer to any condition that causes pain,
dysfunction, distress, social problems, or death to the person afflicted, or similar problems
for those in contact with the person.
• The term disease is used to refer specifically to infectious diseases that result from
the presence of pathogenic microbial agents, such as viruses, bacteria, fungi, protozoa,
multicellular organisms and aberrant proteins known as prions.
• A symptom is a sensation or change in health experienced by a patient e.g., fatigue, pain,
nausea, etc.
• Pathogen (pathos-disease, gen-causing) refers to an organism that causes certain diseases
in animals and plants, e.g., bacteria, virus, fungi, etc.
• Vectors are the carriers that do not cause disease themselves but transmit the disease causing
pathogens from infected person to a healthy person, e.g., female Anopheles mosquito is the
vector of malarial pathogen, Plasmodium.
Human Health and Diseases
Analysis of various PMTs from 2012-201620122013201420152016AIPMT/NEET82245AIIMS1631AMU58124Kerala13K.CET1151J & K845Class XII
Exotoxins
These are released as soon as they are
produced. The diseases brought about by
exotoxins include tetanus, diphtheria and
botulism (food poisoning).Endotoxins
These are retained in the bacterial cells and released
when bacteria die and disintegrate. The diseases caused
by endotoxins include typhoid fever, cholera, bubonic
plague and dysentery.Pathogens cause diseases in two waysToxin secretion
Many microbes produce powerful poisons,
called toxins which cause diseases.Tissue damage
The bacteria responsible for tuberculosis, damage cells and
cause lesions in the lungs.
The bacteria that cause meningitis attack the protective
membranes, called meninges, covering the brain.
Types of toxins