Diseases that are new, increasing in incidence, or showing a potential to increase in the near future • Most are zoonotic, of viral origin, and likely to be vector-borne
emerging infectious diseases
What is pathogenicity in comparison to virulence?
Pathogenicity is a pathogens ability to cause disease and virulence is the extent/degree of pathogenicity
What are 6 ways that a pathogen avoids phagocytosis?
M protien, capsules, the ability to survive in phagolysosome, opa protien; mycolic acids, biofilms and antigenic variation, inhibit adherance
Many organisms gain entry through the mucous membranes, gives examples of mucosal portals of entry
conjunctiva, respiratory tracts, GI tracts, GU tracts
How would you define cytopathic effects of viruses?
Cytopathic effects are visible signs in a host cell of a viral infection
What virulence factor triggers endocytosis?
invasins
proteins produced and secreted by bacteria; soluble in body fluids; gram (+) or (-); can be converted to toxoids; usually effects cell functions; usually destroyed by heat
exotoxins
Give examples of bacteria that produce A-B toxin
Clostridium, diptheria, e. coli, shingella
Would you expect a bacterium to make coagulase and kinase simultaneously?
No, coagulase are bacterial enzymes that coagulate the fibrinogen in blood and convert it into fibrin and kinase breaks down fibrin.
Define LD50 and ID50
ID50-Infectious dose for 50% of a sample population; LD50-Lethal dose for 50% of a sample population.
Name one virulence factor each for fungal, protozoan, helminthic, and algal disease
A-B toxins; membrane-disrupting toxins (leukocidins, hemolysins, streptolysins), genotoxins, superantigens are all endotoxins or exotoxins?
exotoxins
What are ways viruses cause cytopathic effects in the cell?
stop cell synthesis, cause cell to release lysosomes, create inclusion bodies, fusing cells to create syncytium, chromosomal changes, loss of contact inhibition
What is the difference between food infection and food intoxication?
In food infection, microorganism itself causes the illness. In food intoxication, the toxin the microorganism produces causes the illness.
explain the 5 stages of the development of disease
incubation, prodromal, period of illness, period of decline, convalescence
Gram(-), not easily neutralized by antitoxin, causes general discomfort symptoms; fever,
endotoxins
Which are the most often used portals of exits?
The respiratory and gastrointestinal tract.
What function do capsules and M proteins have in common?
They both add to the bacteria's virulence by preventing phagocytosis also M-proteins and capsules are both heat resistant and acid resistant
Most organisms cannot penetrate intact skin; how then would pathogens enter a host through this portal of entry
they would enter through the hair follicles and sweat glands on the skin
In 2012, the morbidity of West Nile encephalitis was 5,674, and the mortality was 286. The morbidity of listeriosis was 121, and the mortality was 13. Which disease is more likely to be fatal?
listeriosis
causes gas gangrene, tetnus, botulism, diptheria, scarlet fever, cyanobacterial intoxification
exotoxins
states that microorganisms cause infectious diseases
germ theory of disease
How do endotoxins produce a fever in the host
macrophage ingests gram(-), bacterium is degraded releasing endotoxin-endtotoxin induces macrophage to release cytokines
What are 3 portals of entry
mucous membranes, skin, parenteral route
compare and contrast contact and vehicle transmissions and give examples
contact transmision includes direct, indirect contact, droplet and congenital transmissions, vehicle Transmission are by an inanimate reservoir- air food water
How do normal microbiota differ from transient microbiota?
normal-permanently colonize the host and do not cause disease under normal conditions;transient- may be present for days, weeks, or months
Explain how A-B toxins is used to overcome host cells
Bacteria secretes toxin, B binds to host cell receptors, PM invaginates, enclosing toxin in PM as it is pinocytosed. A-B toxin separates, A inhibits cell functi
compare and contrast membrane-disrupting toxins and superantigens
MD-lyse host cells by disrupting plasma membranes; SA-cause an intense immune response due to release of cytokines from host cells (T cells)
How does E. Coli cause membrane ruffling?
E. Coli releases invasins which alters the host's actin and form ruffling due the the disruption of the cytoskeleton.
experimental requirements for identifying the agent of an infectious disease
Koch's postulates
Why does the influenza vaccine only offer a few months of protection?
antigenic variation; influenza alters its surface antigens so antibodies formed from the previous vaccination do not bind to the new antigens.
List the membrane disrupting toxins and what they do
Leukocidins – kill phagocytic leukocytes – Hemolysins – kill erythrocytes by forming protein channels – Streptolysins – hemolysins produced by streptococci
What bacteria produces superantigen exptoxins that are responsible for toxic shock syndrome and food poisoning
S. aureus
compare and contrast mechanical transmission and biological transmission and give examples
mechanical transmission involves pathogen being transported by a vector versus biological where part of the pathogens life cycle occurs in the vector
How are nosocomial infections primarily transmitted, and how can they be prevented?
Hospital acquired infections by opportunistic pathogens; pt already sick, surrounded by sick people- prevent spread through universal precautions
Analytical epidemiology: analyzes a particular disease to determine its probable cause, give an example of what an analytical epidemiologist would study
investigating an outbreak of 40 staff getting food poisoning in a hospital, finding what caused the outbreaking
How are endotoxins on medical equipment tested for?
using the limulus amoebocyte lysate (LAL) assay, which will detect even minute amounts of endotoxin.
compare and contrast A-B toxins and genotoxins
A-B toxins contain an enzyme component and a binding component; genotoxins damage DNA causing mutations, disrupts cell division
are released when gram(-) bacteria die or during multiplication; can withstand autoclaving, cannot be used to make toxoids
endotoxins
How and where do pathogens enter the body through the parenteral portal of entry?
they enter in breaks in the skin and mucous membranes; bites, injections and wounds
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