The Manual on Viruses

Modes of transmission
An infectious agent may be transmitted from its natural
reservoir to a susceptible host in different ways.
Here is one classification:
DIRECT: In direct transmission, an infectious agent is
transferred from a reservoir to a susceptible host by direct
contact or droplet spread.
Direct contact: occurs through skin-to-skin contact, kissing,
and sexual intercourse, such as through contact with
open wounds, mucous membranes, or abraded skin contacting
an infec ted animal or its tissues or fluids (e.g.,
blood, saliva, urine). Inoculation of pathogens can occur
from bites or scratches.
Droplet spread: Droplet spread refers to spray with relatively
large, short-range aerosols produced by sneezing,
coughing, or even talking. Droplets containing pathogens
travel through the air and are inhaled by another animal
or human.
INDIRECT: refers to the transfer of an infectious agent
from a reservoir to a host by suspended air particles,
inanimate objects (vehicles), or animate intermediaries.
Airborne: occurs when infectious agents are carried by
dust or droplet nuclei suspended in air. Airborne dust
includes material that has settled on surfaces and become
resuspended by air currents as well as infectious
particles blown from the soil by the wind.
Vehicles: that may indirectly transmit an infectious agent
include food, water, biologic products (blood), and fomites
(inanimate objects such as handkerchiefs, bedding,
or surgical scalpels).
Vectors: such as mosquitoes, fleas, and ticks Transfer
of a pathogen from an infected animal to another animal
or a human by an insect (e.g., flea, tick, mosquito).
THE MANUAL ON VIRUSES
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