Pathogen transmission

Pathogen transmission is the transfer of an infectious agent from a source or host to another host through direct contact, indirect contact, or a vector.

Direct transmission: The spread of an infectious agent through immediate physical contact or short-range exposure between hosts. It covers close-contact routes such as touching, kissing, and exposure to respiratory droplets.
Reservoir of infection: A host, population, or environment in which an infectious agent normally lives and multiplies. Reservoirs maintain pathogens and supply sources from which transmission can occur.
Hand hygiene: Practices that clean hands to reduce the transfer of microbes and infectious agents. Cleaning hands interrupts contact transmission from people, objects, and contaminated surfaces.
Droplet transmission: The spread of infectious respiratory droplets over short distances, typically through mucous membranes. It is commonly distinguished from airborne transmission by particle behavior and typical exposure distance.
Indirect transmission: The spread of an infectious agent through an intermediate vehicle, surface, or organism. It includes routes in which the source and new host do not meet directly.
Infectious disease: A disease caused by an infectious agent entering and multiplying within a host. Transmission is the process by which infectious agents reach new hosts.
Ventilation: The exchange of indoor air with outdoor air or filtered air. Improved ventilation dilutes airborne infectious particles in enclosed spaces.
Contact transmission: The spread of an infectious agent through direct touch or contact with a contaminated surface. It separates touch-based spread from inhalation and other exposure routes.
Airborne transmission: The spread of infectious particles that remain suspended in air and can be inhaled. It explains how some pathogens cross spaces without immediate face-to-face contact.
Susceptible host: A host whose defenses do not fully prevent infection by a particular pathogen. A receiving host must be susceptible for exposure to produce a new infection.

Linked from 6 pages