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This damage caused by the immune system is known as virus-induced immunopathology. [ 23 ] [ 24 ] Specifically, immunopathology is caused by the excessive release of antibodies , interferons and pro-inflammatory cytokines , activation of the complement system , or hyperactivity of cytotoxic T cells .
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 biology, a pathogen (Greek: πάθος, pathos "suffering", "passion" and -γενής, -genēs "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 germ. [1] The term pathogen came into use in the 1880s.
Once a pathogen has been associated with an illness, researchers have reported difficulty displacing these pre-existing theories. [3] [4] 3. Variable pathogenicity: Infection with pathogens can produce varying responses in hosts, complicating the process of showing a relationship between infection and the pathogen. [5]
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 .
Microbial nucleic acids should be found preferentially in those organs or gross anatomic sites known to be diseased, and not in those organs that lack pathology. (ii) Fewer, or no, copies of pathogen-associated nucleic acid sequences should occur in hosts or tissues without disease.
It is the first step of viral replication. Some viruses attach to the cell membrane of the host cell and inject its DNA or RNA into the host to initiate infection. Attachment to a host cell is often achieved by a virus attachment protein that extends from the protein shell (), of a virus.