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The following outline is provided as an overview of and topical guide to concepts related to infectious diseases in humans.. Infection – transmission, entry/invasion after evading/overcoming defense, establishment, and replication of disease-causing microscopic organisms (pathogens) inside a host organism, and the reaction of host tissues to them and to the toxins they produce.
In epidemiology, infectivity is the ability of a pathogen to establish an infection. More specifically, infectivity is the extent to which the pathogen can enter, survive, and multiply in a host. It is measured by the ratio of the number of people who become infected to the total number exposed to the pathogen. [1]
However, for some infectious diseases, the symptoms of the clinical disease may appear after the host becomes infectious. In this case, the pre-infectious or latent period has a shorter duration than the incubation period, the infectious period begins before the end of the incubation period and the host can infect others for some time without ...
Such an infection is called a subclinical infection. In epidemiology , particularly in the discussion of infectious disease dynamics (mathematical modeling of disease spread), the infectious period is the time interval during which a host (individual or patient) is infectious, i.e. capable of directly or indirectly transmitting pathogenic ...
This quantity determines whether the infection will increase sub-exponentially, die out, or remain constant: if R 0 > 1, then each person on average infects more than one other person so the disease will spread; if R 0 < 1, then each person infects fewer than one person on average so the disease will die out; and if R 0 = 1, then each person ...
After the latency period (but before clinical infection) the infected person can transmit the disease without signs of any symptoms. Such infection is called subclinical infection. Incubation period (also known as the latent period or latency period ) is the time elapsed between exposure to a pathogenic organism, a chemical, or radiation , and ...
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. [1] An infectious disease, also known as a transmissible disease or communicable disease, is an illness resulting from an infection.
A human pathogen is a pathogen (microbe or microorganism such as a virus, bacterium, prion, or fungus) that causes disease in humans. The human physiological defense against common pathogens (such as Pneumocystis ) is mainly the responsibility of the immune system with help by some of the body's normal microbiota .