Veterinary Epidemiology and Zoonosis

ROUTES OF TRANSMISSION

Ingestion

• Entry of infectious agents by ingestion via contaminated food, water, soil, etc.
• Infectious agents excreted in the faeces of an affected individual usually ingested due to unhygienic hands is referred to as ‘faecal-oral-transmission’ cycle.
• Examples are colibacillosis, salmonellosis.

Inhalation

• It is an air-borne transmission of an infectious agent via droplets or droplet nuclei in the contaminated environment.
• Examples are avian influenza, tuberculosis, histoplasmosis.

Contact

• Transmission of an infectious agent from the infected animals to man by direct or indirect contact with the infected animals or infective contaminated materials without involvement of an intermediate vectors; or bite or scratch by the infected animals leads to the production of disease.
• Examples are brucellosis, rabies, cat-scratch fever.

Inoculation

• Infectious agents are introduced into the body of the susceptible host through bite wound or scratches of the skin and subsequent inoculation of infective materials into the body wound or needle-prick or biting by arthropod vectors.
• Examples are yellow fever, rabies.

Iatrogenic transmission

• Doctor-induced infection through unhygienic surgical and / or medical practices. The word ‘Iatrogenic’ literally means ‘created by a doctor’.
• Examples are tetanus, rabies due to corneal transplantation (xenozoonosis).

Coitus

• Introduction of infectious pathogens into the susceptible host from the infected host during coitus.
• Example is brucellosis.