Ch.14 Principles of Disease & Epidemiology Part 1 Flashcards
Define Pathology
is the cause & effects of disease
communicable or not communicable
occurrence
incidence & prevalence of disease
Define Etiology
cause of disease
Ex: Koch postulates, fever,
feeling tired
define pathogenesis
the manner in which disease develops
extent of infection
severity of disease
host resistance or susceptibility -> predisposing factors
define bodily changes
structural/functional changes to disease
Sign & symptoms
define virulence
severity of disease ( how serious it is)
define pathogenicity
the ability of a pathogen to cause disease
infectious disease cycle
- microbial pathogen enters reservoir (habitat of the pathogen)
- transmission: infection someone
- susceptible host
- enters host
- Met with host barriers
- invade host
- damage host
- pathology
what is normal microbiota?
bacteria you acquire at birth which you acquire more of as you develop
does not cause harm
define transient microbes:
the microbes that are present in an animal for a short time w/o causing disease.
What can determine the distribution and composition of the normal microbiota?
NUTRIENTS,
PHYSICAL & CHEMICAL FACTORS, DEFENSES OF THE HOST, MECHANICAL FACTORS
what are the physical and chemical factors that impact normal microbiota?
-Temperature
-pH
-available Oxygen
-CO2
-Salinity
-Sunlight
what is the purpose of normal microbiota?
prevent the overgrowth of harmful microbes (called Microbial Antagonism or Competitive Exclusion)
define competitive exclusion
growth of some microbes prevents the growth of other microbes
what is microbial antagonism?
- involves competition among microbes.
how does normal microbiota protect the host?
by competing for NUTRIENTS
producing SUBSTANCES HARMFUL to the invading microbes
affecting conditions such as pH and available OXYGEN.
describe the relationship between the host and normal microbiota.
the symbiotic relationship between host & normal microbiota
explain commensalism
One organism benefits and the other is UNAFFECTED
explain mutualism
benefits BOTH organisms
explain parasitism
one organism benefits by deriving nutrients at the expense of the other
-many disease-causing bacteria
what are opportunistic pathogens?
ordinarily do not cause disease in their normal habitat in a healthy person, but may do so in a different environment
(Asymptomatic carriers)
Ex: Microbes that gain access through broken skin or mucous membranes can cause opportunistic infections
what are primary pathogens?
disease-causing pathogens that are not a part of the normal microbiota
Explain the process of Koch’s postulates:
- microorganisms are isolated from diseased animal
2a: the microorganisms are grown in pure culture
2b: the microorganism are identified
- The microorganisms are injected into a healthy laborer animal
- disease is reproduced in lab animal
5a. microorganism is isolated from this animal and grown in pure culture
5b. Microorganisms are identified
- the microorganism from the diseased host caused the same disease in a laboratory host
what were Koch’s postulates?
- The same pathogen present in all cases
- isolation of the pathogen from diseased host to obatin pure culture
- pure culture isolates to cause disease in susceptible host
- re-isolate pathogen from 2nd host; confirm same as from the first host
Koch believed what?
the pathogen is only present in diseased animal
what were Koch’s postulate exceptions?
healthy individuals could be carriers: be infected and show no symptoms
culturability of the microbe: some cannot be grown in a lab
similarity of symptoms of disease and the same disease caused by multiple pathogens
the same pathogen causing different disease conditions
viral agents
what are symptoms classified as?
subjective(cannot measure)
ex: malaise, headache, dry throat
what are signs classified as?
objective (measurable, visible
ex: fever rash swelling
what is a syndrome?
a group of signs/ symptoms that occur together and characterize a particular abnormality or condition (genetic)
ex: down syndrome, Asperger’s
what are communicable diseases?
can directly/ indirectly spread from host to host
typically have vaccines for it
ex: measles, chickenpox, flu, STDs
what are contagious diseases?
easily spread from person to person
ex: plague, cold, pink eye
what are non-communicable diseases?
do not spread from host to host
ex: tetanus
what is incidence?
number of people in a population who develop a disease during a particular period
(indicated spread of disease)
what is prevalence?
number of people in a population who develop a disease at a specified time, regardless of when it first appeared
(old & new cases; indicated seriousness of the disease)
what do incidence and prevalence both do?
enable an estimation of the range of a disease’s occurrence
its tendency to affect certain groups
what is the frequency of occurrence of disease?
sporadic
endemic
epidemic
pandemic
define sporadic
disease occurs infrequently
ex: tetanus
define endemic
the disease is always present
ex: common cold, cholera
define epidemic
rapid development of disease in a specific area
define pandemic
worldwide epidemic
ex: covid-19
acute disease:
symptoms develop rapidly
short time frame
Ex: flu
chronic disease:
disease develops slowly
longer time frame
Ex: tuberculosis
subacute disease:
symptoms between acute & chronic
latent disease:
disease with a period of no symptoms when the causative agent is inactive
ex: shingles, cold sore
what is herd community?
immune individuals act as barriers to the spread of infection
advantage of vaccination: those not immune are protected
what is a local infection?
limited, confined to a specific area
what is a systemic infection?
spreads throughout the body via the circulatory/ lymphatic system
ex: measles
what is a focal infection?
spread from local infection to specific parts of the body; teeth tonsils, sinuses
what is a sepsis infection?
inflammatory condition due to the presence of toxins/bacteria in blood- spread from the focus of infection
ex: septicemia
what is a primary infection?
causes initial illness (acute)
ex: cold or flu
what is a secondary infection?
caused by opportunistic pathogen following primary infection
occurs when susceptible
ex: ammonia
what is a subclinical (inapparent) infection?
no noticeable signs or symptoms of illness
development of disease
incubation- no signs or symptoms
prodromal-mild signs or symptoms
period of illness- most severe signs & symptoms
period of decline: symptoms decrease
period of convalescentence
what are some predisposing factors?
female vs males
inherited traits
climate & weather
fatigue
age
lifestyle
Chemotherapy
what source of the disease microbes?
reservoir of infection
what is an example of a reservoir?
humans: show symptoms of the disease or do not (carriers)
ex: HIV, STDS, Meningitis
animals: zoonoses
Ex:(rabies; Lyme disease, ebola)
nonliving: soil water
ex:tetanus, cryptospdosis, chlorea, Legionella
what do carriers have?
inapparent infections or have latent disease
what is the infection cycle?
is the route an organism takes from one individual to another
how is a disease transmitted directly?
physical contact source & host
how is a disease transmitted indirectly?
transmission via inanimate object-> fomite
how is a disease transmitted via droplet?
short distance; sneezing coughing
travels <1 meter
how do vehicles transmit disease?
transmit diseases via water food or air also blood drugs
how are waterborne diseases transmitted?
contaminated (fecal) water
the water treatment system is compromised
how are airborne diseases transmitted?
dust particles
pet dander
how are foodborne diseases transmitted?
contaminated food storage @ improper temperature
undercooked food
unsanitary handling of food
how are congenital diseases transmitted?
mother-> child
what are vectors?
typically insects
define mechanical transmission:
passive via body parts
define biological transmisison:
involves parasite life cycle
specific to certain diseases
what are healthcare-associated infections?
are acquired as a result of receiving treatment at a healthcare facility
Microorganisms in hospital environment
opportunistic pathogens: present a danger to hospital patients
(drug-resistant and are previous types
chain of transmission:
direct contact from staff or other patients; indirect( fomites, airborne)
compromised host
resistance to infection is impaired by disease therapy or burns
host compromised due to broker skin or mucous membranes and suppressed immune system
what are universal precautions?
to reduce the transmission of microbes in healthcare and residential settings
what are standard precautions?
basic minimum applied to all levels
ex:
aseptic technique
handling of contaminated materials
frequent handwashing
use of isolation rooms and wards
use of PPE
educate staff
what are emerging infectious diseases?
new or changing, show an increase in incidence in the recent past, or show a potential to increase shortly
what can EID be caused by?
virus
bacterium
fungus
protozoan
helminth
what are the criteria for identifying EID?
distinctive disease symptoms
improved diagnostic techniques allow ID of new pathogen
the local disease becomes widespread
the rare disease becomes common
mild disease becomes more severe
what are the factors contributing to EIDs?
genetic recombination/evolution
misuse of antibiotics/pesticides
climate change
increased human transportation
ecological changes
public health failure
what is epidemiology?
the study of where & when diseases occur and how they are transmitted in the population
what is epidemiology important for
determining the etiology of the disease
identifying other important factors concerning the spread of disease
(demographic data, socioeconomic status; common histories)
developing methods for controlling a disease( control of reservoirs, food inspection, sewage disposal)
assembling data and graphs to outline the incidence of disease (determine disease frequency; test effectiveness of disease control (vaccination)
what is decriptive epidemiology?
collection and analysis of data describing the occurrence of disease
what did John Snow do?
mapped occurrence of cholera cases in London
source traced to Broad Street water pump
what is analytical epidemiology?
analyzes a particular disease to determine its probable cause
what did Florence Nightingale do?
used medical statistics to demonstrate high mortality rate due to disease (typhus) among soldiers during the war
what is experimental epidemiology?
it involves a hypothesis and controlled experiments
what did Semmelweis do?
handwashing decreased the incidence of childbirth fever (puerperal sepsis)
what is case reporting?
health care workers report specified diseases to local, state, and national offices
ex: AIDS, meningitis, STD’s tetanus
what is the purpose of case reporting?
it establishes the chain of transmission
what are physicians required to report occurrence?
nationally notifiable infectious diseases
what does the CDC do?
collects & analyzes epidemiological info in the U.S.
Publish morbidity & mortality weekly report (MMWR)
what is morbidity?
incidence of a specific notifiable disease
what is mortality?
deaths from notifiable diseases
