Introduction to Infectious Disease Lecture Review Flashcards
a disorder caused by pathogenic organisms.
infectious disease
the time between catching an infection and symptoms appearing
incubation period
a microorganism that produces disease.
Pathogen
True/False, ALL MICROORGANISMS ARE PATHOGENS!!
False. Some are part of our normal flora
the ability of an organism to produce disease
Virulence
Any person,animal, plant, soil or substance in which an infectious agent normally lives and multiplies
Reservoir
diseasesconsidered to be of great public health importance
Reportable diseases
disease that can be transmitted from animals to humans
Zoonosis
List the 4 major categories of pathogenic organisms that cause infectious disease
Bacteria
Fungi
Viruses
Parasites
Prokaryotic organism, typically a few mm in length, ranging fromspheres to rods and spirals.
Bacteria
How are bacteria named?
Binomial with genus and species.
Genus is suggestive of morphology, discoverer or other characteristics
species is suggestive of metabolic features, biochemical characteristics or disease
What is the “Genus” of a bacteria
The first part of the name, always always capitalized and underlined; Genus is suggestive of morphology, discoverer or other characteristics
What is the “species” of a bacteria
the second part of the name, always capitalized and underlined; species is suggestive of metabolic features, biochemical characteristics or disease
Staphylococcus epidermidis is a type of bacteria. Which part of this name represents the Genus?
Staphylococcus
Staphylococcus epidermidis is a type of bacteria. Which part of this name represents the species?
epidermidis
What is the purpose of a bacterial cell wall?
Determine shape of a bacterium
Provide strong structural support
What is gram staining used for?
Differences in structure determine Gram staining.
Gram staining helps identify the bacterium as either gram positive or gram negative.
A gram positive organism will stain
purple
A gram negative bacteria will stain
pink
A bacteria has “Bacillus” in its name. What shape will this organism be?
rod shaped
A bacteria has “coccus” in its name. What shape will this organism be?
spherical/round
A bacteria is seen under the microscope as multiple round cells in grape-like clusters. Would you expect this to be a Streptococcus sp. or a Staphylococcus sp.?
Staphylococcus sp.
A bacteria is seen under the microscope as multiple round cells in long chains. Would you expect this to be a Streptococcus sp. or a Staphylococcus sp.?
Streptococcus sp.
a large group ofeukaryoticorganisms that includes microorganisms such asyeastsandmolds, as well as the more familiar mushrooms.
Fungi
Fungi can be divided into two groups:
Macroscopic fungi (mushrooms, puffballs, gill fungi)
Microscopic fungi (molds, yeasts)
Cells of microscopic fungi exist in two basic morphological types:
Yeasts
Hyphae
Ex of disease caused by microscopic fungi:
Yeasts–ear infections, caused by Malassezia sp.
Hyphae-ringworm, caused by Microsporum or Trichophyton sp.
Describe what a yeast would look like under the microscope
purple stain, larger than a bacteria, “snowman” or “packing peanut” appearance
a smallinfectious agent that replicates only inside the livingcellsof other organisms
virus
The basic structure of a virus consists of
capsid, nucleic acid, +/- an envelope.
True or False. The nucleic acid of a virus consists of either DNA or RNA, but never both.
True
non-mutual relationship betweenspecies, where one species, theparasite, benefits at the expense of the other, thehost.
Parasitism
The three main types of organisms causing parasitic infections
protozoa,helminths, andectoparasites
parasites that are single cells
Protozoa
Protozoal life stages include:
Trophozoite: motile, feeding stage, requires ample food and moisture to remain active
Cyst: dormant, resting stage for when conditions are unfavorable for feeding
How do protozoa move?
Pseudopods: blunt, branched, or long and pointed; produces amoeboid motion
Flagella: long, sheathed ,cylinders
Cilia: similar to flagella, but shorter and more numerous
2 major groups of parasitic helminthes are
Platyhelminthes and Aschelminthes
Flatworms have a very thin, often segmented body are classified as:
Platyhelminthes (cestodes and flukes)
Nematodes have elongated, cylindrical, unsegmented body and are classified as
Aschelminthes
Examples of nematodes
Roundworms
Whipworms
Hookworms
Pinworms
animals harbor an infectious agent without displaying clinical signs and may transmit the infectious agent to other animals.
carrier animal (or reservoir animal)
What is “horizontal” disease transmission?
Transmission of disease among unrelated animals
What is “vertical” disease transmision?
Transmission of disease from a parent to an offspring in the period prior to birth or immediately after birth
What is a “vector”
an organism, typically a biting insect or tick, that transmits a disease or parasite from one animal or plant to another.
What is a “fomite”?
inanimate object that can harbor a disease causing organism
Examples of horizontal transmission:
Direct contact
Airborne
Droplet
Indirect (fomites)
Vector-borne
Fecal-oral
What is transmission by direct contact?
Requires physical contact between infected and susceptible animals and the physical transfer of microorganisms
Examples: Licking, Rubbing, Biting, Coitus
True/False. Diseases spread by direct contact cannot survive long away from host
True!
True/False. Organisms spread via airborne transmission must be capable of surviving for long periods of time outside the body and must be resistant to drying
True
What is transmission by droplet contact?
Droplets containing microorganisms can be generated when an infected animal coughs, sneezes, or barks
Droplets are too large to be airborne for long periods of time, and quickly settle out of air.
What is transmission by indirect contact?
A susceptible animal is infected from contact with a contaminated surface or utensil (a fomite).
Some organisms are capable of surviving on surfaces for an extended period of time, serving as a source of transmission.
What is a biological vs a mechanical vector?
Biological vectors, such as mosquitoes and ticks may carry pathogens that can multiply within their bodies and be delivered to new hosts, usually by biting. Mechanical vectors, such as flies can pick up infectious agents on the outside of their bodies and transmit them through physical contact.
What is fecal-oral transmission?
Inside the digestive system, the microorganisms multiply and are shed from the body in feces.
Microorganisms enter the body through ingestion.
How can two animals come into contact with a disease in their environment and only one of them get sick?
Host Factors (Age, Nutritional Status, Health Status, Immunization status, Stress)
Environmental Factors (Temperature, Humidity, Sanitation)
Agent Factors (Virulence, Mode of Transmission, Amount of Exposure)
What characteristics of Infectious Disease that Influence Potential for Introduction?
- its’s persistence in the Environment
- Whether it’s immediately Infectious or needs time to develop to infectious stage
- The organisms life cycle– does it have an Indirect life cycle, requiring development in vector/another host?
