In
epidemiology
Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population.
It is a cornerstone of public health, and shapes policy decisions and evi ...
, infectivity is the ability of a
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...
to establish an infection. More specifically, infectivity is a pathogen's capacity for
horizontal transmission — that is, how frequently it spreads among
hosts that are not in a parent–child relationship. The measure of infectivity in a population is called
incidence.
Infectivity has been shown to
positively correlate with
virulence
Virulence is a pathogen's or microorganism's ability to cause damage to a host.
In most, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its ability to ...
, in plants. This means that as a pathogen's ability to infect a greater number of hosts increases, so does the level of harm it brings to the host.
A pathogen's infectivity is subtly but importantly different from its
transmissibility, which refers to a pathogen's capacity to pass from one organism to another.
See also
*
Basic reproduction number
In epidemiology, the basic reproduction number, or basic reproductive number (sometimes called basic reproduction ratio or basic reproductive rate), denoted R_0 (pronounced ''R nought'' or ''R zero''), of an infection is the expected number of ...
(basic reproductive rate, basic reproductive ratio, ''R''
0, or ''r nought'')
References
Epidemiology
{{infectious-disease-stub