Basic Concepts on Infection
Human or animal colonized by a pathogen.
Host
Number of NEW infection cases
Incidence
Natural barrier and harbors normal flora
Skin
Period when microorganisms begin replication without identifiable symptoms
Incubation period
Protect mucous membranes of genitourinary, gastrointestinal, and pulmonary systems.
Found in breast milk and tears.
Not actively related to infection. Has a protective and preventive role.
IgA
Pathogen source
Examples: person or inanimate object (Fomite)
Reservoir
Number of active ongoing infections
Prevalence
Possible entry point for thousands of microorganisms through inhalation
Respiratory Tract
Initial symptoms appear, often vague and general
Prodromal stage
Binds antigens to B cells.
Attached to the surface of the B cells.
Most active in early stage of infection, when the antigen has entered the body.
IgD
Pathogen living in a host
Colonization
Incidence and prevalence are stable
Endemic
Contaminated food or drink
Fecal-oral transmission
Gastrointestinal Tract
Full infectious disease
Signs and symptoms are present
Immune system is fully engaged
Acute stage
Active in allergic reactions; binds to mast cells and basophils to release histamine and leukotrienes.
Found on mast cells in pulmonary and gastrointestinal tracts.
Not related to infection. Found in persons with allergies.
IgE
Ability to produce disease
Virulence
Abrupt increase in incidence in location
Epidemic
Urethra is common route
Genitourinary Tract
Body progressively eliminating the pathogen
This can last for days, weeks or months
Convalescent stage
Activates complement to release inflammatory and bactericidal mediators. It Confers long-term immunity, is active against viruses, bacteria, and antitoxins, and moves across the maternal-fetal barrier.
Found throughout the bloodstream.
Most active in late disease, recovery, and long after
IgG
Living being that can carry a pathogen from reservoir to host
Vector
Pandemic
Blood transfusions
Blood-blood transmission
Pathogen eliminated from the body
Resolution phase
Initiates complement activity and further immune responses. Controls ABO blood reactions.
Found throughout the bloodstream.
Most active in early infection.
IgM