Final Flashcards
Refers to the number of new cases in a location over a specified time, and reflects the risk a person has of acquiring that disease
Incidence
describes the total number of active cases of a disease in a given location at a given time, regardless of when a case first developed (old plus new)
Prevalence
larger than normal number of individuals in a population become infected over a short period of time
Epidemic
disease always present at a low frequency in a population
endemic
any bird, mammal, insect or other animal that harbors an infectious agent and is indigenous to a geographic area
reservoir
epidemic that occurs over a wide geographic area, typically the world
pandemic
first case of the disease
index case (patient zero)
examines the distribution and determinants of disease in a human population
epidemiology
infectious disease that recently appeared in a population
emerging disease
vehicle transmission
food, water, or air
vector transmission
any living organism that can carry a disease (typically insects that bite like mosquitos)
direct contact transmission
direct contact with infected; typically through hands
indirect contact transmission
touching something inanimate that the infected touched; like clothes, tissues, doorknobs
droplet transmission
respiratory droplets within 3 feet of release
the number of disease cases per 100,000 individuals
Morbidity rate
the number of deaths from a disease for every 10,000 individuals
Mortality rate
a disease found occasionally in a region with cases occurring mainly in isolation from each other
Sporadic
complete fully developed infectious viral particle
virion
Virion Taxonomy
order - virales
family - viridae
genus - virus
Means of Classifying viruses
gnome composition
replication and mRNA expression strategies
morphology of capsid (protein coat)
host range
viral envelope
membrane derive from the host
which structure of a virus provides rigid protection from degradation and enables it to persist when it is transmitted outside the host?
protein capsid
which of the following steps is NOT part of the life cycle (replication) of a lytic phage?
The phage DNA integrates into the bacterial chromosome becoming a prophage
All of the following criteria are used to classify viruses according to the International Committee on Taxonomy of Viruses EXCEPT:
a. mechanisms of replication and mRNA expression
b. genome composition
c. mutation rate
d. capsid morphology
c. mutation rate
The gnome of ____ ssRNA viruses an serve directly as mRNA and be translated by the host cell’s ribosomes to form viral proteins.
positive-sense (+)
T/F: Within a multicellular host, receptor molecules can determine viral tropism (tendency to infect a particular tissue type)
true
Some viral species obtain their _____ directly from membranes in the host cells they invade.
envelope
During a lysogenic viral cycle, the integrated phage genome is referred to as a _____.
prophage
T/F: Viroids are infections agents that contain only RNA.
True
T/F: The most current theory for how prions functions is that prions are a unique form of lytic viruses that make spongy holes in the brain causing a fatal form of encephalopathy
False
After an initial outbreak of cold sores, the herpes simplex virus (HSV-1) which caused the cold sores enters a ______________ which may allow it to cause future cold core outbreaks.
a latent state in nerve ganglia
Serological test
detect antibodies or virion antigens
Molecular tools for virus identification
PCR
DNA profile using electrophoresis (RFLPs)
Cultivation of Viruses
grown in living cells:
phages cultivated within bacterial cells
animal viruses grown in embryonic eggs
lytic cycle
phage causes lysis and death of host cell
attachment by tail fibers, penetration through cell wall, Biosynthesis: production of phage DNA and proteins, assembly of newly synthesized phage particles, phage lysozyme destroys cell well
lysogenic cycle
temperate phages incorporate DNA into host DNA (prophage)
3 results: immunity to reinfection, phage conversion, specialized transduction
viruses that remain dormant for long periods
latent viral infections
disease progresses slowly over a long period
persistent viral infection
infectious naked RNA
viroid
class of infectious agents thought to consist solely of proteins, mad cow disease
prions
T/F: microorganisms that reside on or within a host without causing infection/disease are referred to as the normal microbiota (microbiome).
True
Microorganisms using the _____ route of entry invades tissues via injections, bites, cuts, and/or surgical procedures
parenteral
Which of the following would be considered a bacterial virulence factor (e.g. contributes to the bacteria’s pathogenicity)?
capsules
cell wall components
axial filaments/flagella
endospores
Virulence factors
contribute to the bacteria’s pathogenicity
cell wall
fimbriae - attachment
flagella/axial filaments - motility
capsules
incomplete phagocytosis
exoenzymes
endospores
Generally speaking, which of the following is the most commonly used portal of entry for pathogens?
mucus membranes (e.g., gastrointestinal, respiratory, genitourinary)
An endotoxin is
a toxic lipid that is a component of the outer LPS membrane of gram negative bacteria
Organism that under NORMAL circumstances does not cause disease
opportunistic pathogen
one organism lives at the expense of the host
parasitism
aspects of a disease that are only apparent to the patient (e.g., headache, nausea, fatigue)
symptoms
disease caused by a pathogen which may or may not spread between hosts
infectious
a disease caused by a pathogen that will not spread between hosts
non-communicable
T/F: avoiding the host’s defenses is the critical step in a pathogen being able to cause disease
False
An individual’s susceptibility to disease can be influenced by which of the following factors
poor nutrition
lifestyle choices
antibiotic therapy
emotional disturbances
genetic background
T/F: the most acute signs and symptoms of a disease appear during the prodromal phase of an infectious disease
False
propagated epidemic
starts with one person and spreads to others (like the flu)
common source epidemic
everyone got sick all from the same source (like eating at the same restaurant)
the percent of individuals in a population immune to a disease; it is increased significantly through vaccination
Herd Immunity
Which of the following is not an example of direct transmission?
a. sharing food or drinks
b. kissing
c. shaking hands
d. sexual intercourse
a. sharing food or drinks
An island nation normally has low background level of cholera. After an earthquake, sanitation is disrupted and cholera cases spike to high levels on the island but not other areas of the world. The spike in cholera cases is an example of an
epidemic disease
Lily (who had lice) brings a comb to school for picture day. After Licey Lily combs her hair, Leticia asks to borrow the comb. Leticia later is diagnosed with lice. In this example, the comb is a
fomite
Vaccinating domesticated and wild (if possible) animals
lowers the number of reservoirs and reduces transmission of zoonotic diseases to humans
a patient in the hospital with a urinary catheter develops a bladder infection during their hospital stay. This is an example of a _______ infection.
nosocomial
T/F: one of the basic goals of vaccination is to increase herd immunity
true
The epidemiologic triad (triangle) of disease refers to:
pathogen, susceptible host, environment
Ebola epidemics occasionally occur. Where does the virus that causes Ebola “hide” in between epidemics? It is thought that bats naturally harbor the virus, and this would be considered
a reservoir
compounds in food that induce the growth or activity of beneficial microorganisms such as bacteria and fungi (food for microbiota)
Prebiotic
foods or supplements that contain live microorganisms intended to maintain or improve the “good” bacteria in the body
probiotics
Acid-producing microbes used to supplement commercial mining; many antibiotics come from actinomycetes
biomining
used to detect chemical pollutants
genetically engineered biosensors
the use of microbes to detoxify environmental containments
bioremediation
Replication of Animal Viruses
Attachment - attach to cell of membrane
penetration - by endocytosis or fusion
uncoating - by viral or host enzymes
biosynthesis - production of nucleic acid and proteins
maturation - nucleic acid and capsid assemble proteins
release - by budding or rupture
measure of oxygen required to fully metabolize organic matter in water; normally about 10mg/L of oxygen can be dissolved in water
Biochemical Oxygen Demand (BOD)
a sudden increase of a formerly limiting nutrient in an aquatic environment, leading to an overgrowth of algae and grazing bacteria and subsequent oxygen depletion
eutrophication
Koch’s Postulates
demonstrates that specific microbes cause specific diseases
Predisposing factors for infectious disease
factors that affect disease virulence
genetics, age, climate, inadequate nutrition, habits and lifestyle, chemotherapy, being a punk ass bitch
steps of water treatment
- coagulation: sedimentation and flocculation
- filtration: sand or coal
- disinfection: chlorine; ozone; UV light
Health care-associated infections (HAIs) and nosocomial infections
infections you get in the hospital, due in part to poor heath of patients and antibiotic-resistant nature of bacterial lurking in hospitals
Common Eradication/public heath Efforts
Improving Sanitation
Reservoir elimination
Vector control
Vaccination and Chemotherapy
microbiota relationships with host
protects from other disease-causing microbes
(competitive exclusion and chemical warfare)
Steps of infection
Gain entrance to host
adherence
avoid host defenses
colonization
cause host damage
leave host if possible
pathogenic portals of entry
mucus membranes (respiratory tract, gastrointestinal tract, genitourinary tract, placenta)
skin
parenteral route (bites, puncture, injection, wound)
exotoxins
produced mostly by Gram+ bacteria as part of their metabolism; secreted externally or released after cell lysis
lipid A portion of outer LPS membrane of gram- cell wall; released when cells die, and cell walls lyse; antibiotics may cause an immediate worsening of symptoms. Chills, fever, weakness, aches; disseminated intravascular coagulation (DIC); septic shock
endotoxins
Pathogenic portals of exit
Respiratory and gastrointestinal tract (most common)
genitourinary tract
skin/wounds
insects biting
needles and syringes
Carbon Cycle
autotrophs fix CO2 into organics
heterotrophs consume autotrophs
carbon reenters the environment (respiration, decomposition, fossil fuels)
nitrogen cycle
deamination - amino groups removed from proteins and converted to ammonia
ammonification - breakdown of organic nitrogen releasing ammonia
nitrification - oxidation of ammonium into nitrite; nitrite can be oxidized to nitrate
denitrification - nitrate reduction leads to loss of nitrogen back to the atmosphere as nitrogen gas
sulfur cycle
sulfates are incorporated into plants, animals and bacteria as disulfide bonds in proteins; proteins decompose and sulfur released as H2S; some lithotrophs oxidize H2S to form sulfates
phosphorus cycle
limiting factor for plant and animal growth (used in detergents and fertilizers, runoff may lead to eutrophication)
exists primarily as phosphate ion (PO4 3-)
Common Phases of infectious diease
Incubation period - no signs or symptoms
Prodromal period - vague/general symptoms
Illness
Decline
Convalescence - no signs or symptoms
Assimilation
process by which organism acquire elements to build cells
dissimilation
process of breaking down organic nutrients into inorganic minerals
Freshwater zones
littoral zone, limnetic zone and profundal zone, benthic zone
Marine zones
Neuston (about 10 micrometers) - air water interface
euphotic zone (100-200m) - light, phototrophs grow
aphotic zone - below light, heterotrophs & lithotrophs
benthos - ocean floor; benthic organisms
endomycorrhizal fungi
vesicular-arbuscular mycorrhizae (VAM)
Ectomycorrhizal fungi
colonize the rhizoplane
Benefits of Biofilms
cell-to-cell communication
share resources
protection
facilitates transfer of genetic information
Lichens consist of an intimate mutualistic symbiosis between a fungus, an alga, and/or cyanobacteria. What is one primary role of the cyanobacteria in the association?
nitrogen fixation
which region of marine habitat refers to the microscopic interface between water and air?
neuston
all of the following are likely to be found among the benthic microbes EXCEPT:
a. barophiles
b. methanogens
c. phototrophs
d. psychrophiles
e. thermophiles
phototrophs
eutrophic lakes typically support ten times the microbial concentrations of an oligotrophic lake. which of the following statements is NOT true of eutrophic lakes?
population of aquatic animals like fish increases due to an abundance of oxygen
bacteria found growing in between crystals of solid bedrock as deep as 3km below Earth’s surface are called
endoliths
fungi play a much larger and more significant role in the decomposition of terrestrial biomass than they do in marine ecosystems. This is because fungi
can degrade the abundant lignin in terrestrial habitats
Vascular abuscular mycorrhizae (VAM) are an example of which of the following?
endomycorrhizae
Microbes participate in which step of wastewater treatment by decomposing organic material?
secondary
wastewater treatment generates which of the following gases during anaerobic sludge digestion in quantities sufficient for recovery as a fuel source?
methane
What types of bacteria will carry out nitrification (oxidation of nitrates & nitrites)?
chemolithotrophs
