医学英语感染病.ppt

医学英语感染病
由NordriDesign提供

Types of pathogens
eu-, Good; well; true
pro-, before
karuo-, nut orrotection while disrupting their hosts' nutrient absorption, causing weakness and disease.
helminths
Helmins = worm
Hookworms attached to the intestinal mucosa.
arthropods
Greek arthron, "joint", and podós "foot", which together mean "jointed feet”
Culex Mosquito
Aedes Mosquito
Ticks
Pathogen factors
pathogenicity
virulence
is the ability of a pathogen to produce an infectious disease in an organism.
The virulence factors of bacteria
Methods by which bacteria cause disease
Adhesion
Colonization
Invasion
Immune response inhibitors
Toxins
1
2
3
4
5
The virulence factors of bacteria
Adhesion. Many bacteria must first bind to host cell surfaces..
Colonization. Some virulent bacteria produce special proteins that allow them to colonize parts of the host body.
Invasion. Some virulent bacteria produce proteins that either disrupt host cell membranes or stimulate endocytosis into host cells. These virulence factors allow the bacteria to enter host cells and facilitate entry into the body across epithelial tissue layers at the body surface.
Immune response inhibitors. Many bacteria produce virulence factors that inhibit the host's immune system defenses.
Toxins. Many virulence factors are proteins made by bacteria that poison host cells and cause tissue damage.
Methods by which bacteria cause disease
invasion
minimum lethal dose  (MLD) the smallest amount of toxin that will kill an experimental animal.
Minimum infective dose
median infective dose  (ID50) the amount of pathogenic microorganisms that will cause infection in 50 per cent of the test subjects.
infective dose  that amount of pathogenic organisms that will cause infection in susceptible subjects.
Host factors
susceptibility
disposition
Immune system
Antibody, immunoglobulin
Iceberg concept of infection
Infectious disease spectrum
If a large number of indi