Today is our topic of discussion Agents’ of diseases
Agents’ of diseases
Disease agent:
An agent is a substsnce which may be living or non-living or a force, which is tangible or intangible, whose mere presence. relative excess or relative lack. is essential for the occurrence of disease or health related events.
A disease may have a single agent, a number of independent alternative agents (at least one of which must be present), or a complex of two or more factors whose combined presence is essential for the development of the disease.
Types of agents:
Biologically:
- “Living” agents: Viruses, bacteria, protozoa, helminths, arthropods etc.
- “Non-living” agents: Heat and cold, water, nutrients, toxic substances etc.
Aetiologically:
- Biological agents- Bacteria, virus, fungus, protozoa, helminths.
- Nutrient agents – Any excess or deficiency in intake of nutritive elements, may result in nutritional disorders. Ex-PEM, IDD (Jodine Deficiency Disorder).
- Physical agents – Exposure to excess heat, cold, radiation, sound, etc.
- Chemical agents – Endogenous: urea (uraemia), bilirubin (jaundice), uric acid (gout).
- Mechanical agents – Crush injury, sprain, dislocation.
- Absence or insufficiency or excess of a factor necessary to health Hormones. congenital heart disease.
- Social agents – Poverty, smoking, abuse of drugs & alcohol, unhealthy life-style.
Host
Definition:
A person or other animal, including birds and arthropods that afford subsistence or lodgement to an infectious agent under natural conditions. [Chapter 14]
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