BIOL 2300: EPIDEMIOLOGY (EXAM ONE)
79 Cards in this Set
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Epidemiology
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the study of causes and disease patterns in populations and the application of that study to the control of disease and infection
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west nile > find out carried by mosquitos > try to control mosquitos
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what is an example of epidemiology?
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epidemiologists
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health detectives, cornerstone to public health
collect, compile data about sources of disease
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design infection control strategies, prevent or predict spread of disease
use expertise in diverse disciplines including ecology, microbiology, sociology, statistics, and psychology
many of our daily habits (hand-washing, waste disposal) based on work of epidemiologists
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what are some responsibilities of epidemiologists?
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Communicable
Non-communicable
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what are the two types of diseases?
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Communicable diseases
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transmitted from one host to the other
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measles
colds
influenzas
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what are examples of Communicable diseases?
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interactions between environment, pathogen, and host
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what are transmission of communicable diseases determined by?
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improved sanitation (prevent)
antimicrobial medications (kills or inhibits pathogens)
vaccination (increases host resistance)
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control of what factors may break infection cycle of communicable diseases?
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Non-communicablediseases
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do not spread from host to host
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from individual's moral microbiota or environment
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how do microorganisms most often arise in non-communicable diseases
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Primary pathogen
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microbe or virus that causes disease in otherwise healthy individual
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plague
malaria
measles
influenza
tb
tetanus
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what are examples of diseases caused by primary pathogens
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opportunistic pathogen
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causes disease only when body's innate or adaptive defenses are compromised or when introduced into unusual location
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pseudomonas
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what is an example of a disease caused by an opportunistic pathogen
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refers to degree of pathogenicity
severity? how bad is the disease
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virulence
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virulence factors
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traits that allow microorganism to cause disease
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pili
toxin
proteins
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what are examples of virulence factors?
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rate
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are epidemiologists more concerned with absolute number of cases or rate
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attack rate
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proportion of people who become ill in a population after exposure
reflects infectious dose, immune status of population
how many people in certain time
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incidence rate
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number of new cases/time/population
measure of risk of an individual contracting a disease
new cases
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prevalence
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total number of cases at any time or for a specific period in a given population
reflects overall impact of disease on society
total cases
expressed per 100k people
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morbidity
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the state of having poor health or disease in a population, morbidity rate is related to the prevalence of the disease
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contagious disease
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what often has a high morbidity rate?
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mortality
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overall death rate in population
most associated with non-communicable diseases in developed countries
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case-fatality rate
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percentage of population that dies from a specific disease
plague and ebola feared because of very high rate
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Endemic disease
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diseases constantly present in population
e.g common cold, measles in US
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epidemic
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disease with an unusually large number of cases
can be from introduced or endemic disease
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outbreak
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group of cases at specific time and population
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pandemic
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worldwide outbreak
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reservoirs of infection
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natural habitat in which pathogen lives
in or on animal, human, or in environment
identification important in disease control
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may be exclusive or exist in other animals, environment
often easier to control
symptomatic or asymptomatic
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facts about human reservoirs
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symptomatic
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obvious source of pathogens
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asymptomatic
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harder to identify, may not realize, can spread to others
up to 50% of women infected with gonorrhea
many people carry staph
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gastrointestinal pathogens, rabies virus
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common non-human animal reservoirs
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zoonoses (zoonotic diseases)
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primary exist in animals but can be transmitted to humans
eg. plague, rabies
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environmental reservoirs
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diseases difficult or impossible to eliminate in _________ reservoirs
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body surface or orifice
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entry and exit route for pathogen
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intestinal tract
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where are pathogens shed in feces?
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respiratory tract
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where pathogens exit in droplets of saliva, mucus
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skin
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where pathogens shed on skin cells
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genital
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where pathogens are in semen and vaginal secretions
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must be transmitted but also colonize surface or enter host
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how do pathogens cause disease?
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vertical transmission
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transmission from a pregnant woman to her fetus or mother to infant during childbirth or breast feeding
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horizontal transmission
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transmission from person to person via air, physical contact, ingestion of food or water, or vector
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direct contact
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transmission by handshake, sexual intercourse
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infectious dose important
from hands, can be ingested: fecal-oral transmission
hand washing considered single most important measure for preventing spread
some pathogens can't survive in environ, require intimate sexual intercourse
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facts about direct contact
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indirect contact
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transmission from inanimate objects, or fomites
eg, clothing, table-tops, doorknobs, drinking glasses
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fomites
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substance or material that has pathogens on it
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droplet transmission
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transmission where respiratory droplets generally fall to ground within a meter from release
densely populated buildings
spread minimized by covering mouth when sneezing
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food and water transmission
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transmission by contamination
animal products from animal intestines
cross-contamination
municipal water systems can distribute to large numbers
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air transmission
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transmission by respiratory diseases commonly transmitted
particles larger than 10 um usually trapped by mucus
smaller particles can enter lungs, carry pathogens
number of bacteria in air proportionate to huber of people
ventilation systems, negative pressure, HEPA filter
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HEPA filters
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remove organisms from air
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adherence and colonization
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ways to establish infection
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adhesions
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attached to host cell receptor
often located at tips of pili (called fimbriae)
can be component of capsules or various cell wall proteins
binding highly specific; exploits host cell receptor
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capsule
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polysaccharide surrounding the protein
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colonization
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growth in biofilms (community of organisms)
siderophores (low molec. weight molecules that bind iron)
avoidance of secretory lgA
compete with normal microbes, tolerate toxins
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lgA
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first antibody given to children by mothers breast milk
kills bacteria
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produce toxins that are ingested
colonize mucous membranes, produce toxins
invade host tissues, avoid defenses
invade host tissues, produce toxins
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what are different methods of pathogenesis?
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vector
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living organisms that can carry pathogen
most commonly arthropods: mosquitos, fleas, ticks, lice
can be mechanical (eat it) or biological (bug bite)
control important in preventing disease
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the dose
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minimum huber of pathogens required to cause disease
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incubation period
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influences extent of spread
how long does it take to show symptoms?
longer period= more extensive spread
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immunity to pathogen
general health
age
gender
religious and cultural practices
genetic background
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what are 6 host factors that influence disease epidemiology?
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previous exposure, immunization
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how does immunity to pathogens influence disease epidemiology?
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malnutrition, overcrowding, fatigue
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how does general health influence disease epidemiology?
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very young and elderly generally more susceptible
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how does age influence disease epidemiology?
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women more likely to develop UTIs
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how does gender influence disease epidemiology?
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breastfeeding provides protective antibodies to infant, raw fish consumption
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how does religious and cultural patterns influence disease epidemiology?
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natural immunity varies widely
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how does genetic background influence disease epidemiology?
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emerging disease
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infections that have recently appeared within a population or those whose incidence or geographic range is rapidly increasing or threatens to increase in the near future
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healthcare-associated infections (HAIs)
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what is one of the top 10 causes of death in US
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nosocomial infections
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only occur in hospital
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Escherichia coli and members of the Enterobacteriaceae
Pseudomonas species
Staphylococcus aureus
other Staphylococcus species
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what are four common HAIs?
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Escherichia coli and members of the Enterobacteriaceae
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HAIs that cause UTIs and other infections
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pseudomonas species
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HAIs in urinary tract an burn wounds. grow in moist places
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Staphylococcus aureus
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HAIs in surgical site infections
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other staph species
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other staph species
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other patients
healthcare environment
healthcare workers
patient microbiota
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what are reservoirs of infectious agents in healthcare settings?
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fomite transmission
direct transmission
personnel
airborne transmission
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what are transmission types in healthcare settings?
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BIOL 2300: EPIDEMIOLOGY (EXAM ONE)